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Past research efforts have developed several self-centering beam-to-column connections for minimizing structural damage in steel moment frames after severe earthquakes. However, less focus has been on low-damage column base connections. Severe damage at the base of columns in conventional steel structures with moment frames is likely during an intense earthquake, rendering the building nonresilient. This paper evaluates the application of a recently developed viscoplastic damper in low-damage column base connections. The proposed viscoplastic damper is a rubber-steel core damper (RSCD), which consists of a high-damping rubber layer and several ductile steel bolts. The proposed column base connections prevent damage and inelastic deformations in the steel column and its base plate by allowing a rocking mechanism at the base of the column and limiting damage to easily replaceable steel bolts in the dampers. The paper discusses the design and behavior of the column base connections equipped with RSCDs. Continuum finite element models of RSCD dampers were developed and validated using experimental results. The rocking response was validated using experimental results for rocking columns with a silt damper. A total of 21 finite element models of rocking columns with RSCD were used to numerically examine the column response to combined axial loading and cyclic lateral loading. The influence of different parameters on the cyclic response of the proposed column base connections was also evaluated. These parameters are steel bolt diameter-to-length ratio (d/h), rubber thickness, column axial compressive load, number of bolts, and steel material type. The results confirmed the effectiveness of the proposed column base connection for minimizing damage to the steel column and its base plate. An optimal d/h ratio of 0.4 was found for the design of RSCDs. In addition, analytical formulas are presented to evaluate the yield and ultimate strength of the proposed column base connection, and the comparison with FEM results indicates that the presented mechanism has sufficient accuracy. [ABSTRACT FROM AUTHOR]

Timber-framed masonry structures are widely used around the world, and their seismic performance is generally poor. Most of them have not been seismically strengthened. In areas with high seismic fortification intensity, there are great potential safety hazards. And it is urgent to carry out effective seismic reinforcement. However, due to the complicated construction process of the existing reinforcement technology, the poor durability of the reinforcement materials, and the significant disturbance to the life of the original residents, an efficient single-story timber-framed masonry structure reinforcement technology suitable for comprehensive promotion and application has not been explored. In this paper, a fiber-reinforced cement mortar (FRCM) material was proposed. A 1/2 scale model of a single-story timber-framed masonry structure was taken as the research object. The method of strengthening a single-story timber-framed masonry structure with FRCM layer was adopted. And the shaking table test of the model before and after reinforcement was carried out in turn. The dynamic characteristics, failure modes, acceleration response and displacement response of the FRCM layer-strengthened structure were analyzed through comparisons of the two cases. The experimental results showed that the FRCM layer significantly improved the seismic performance of the seismic-damaged single-story timber-framed masonry structures. The X- and Y-direction natural frequencies of the model structure were increased by 31.30% and 30.22%, respectively, after the structure was strengthened with FRCM. During a rare eight-degree earthquake, the inter-story displacement angles in the X- and Y-direction of the unreinforced model reached 1/98 and 1/577, respectively, and the structure was destroyed, while the inter-story displacement angle of the FRCM-reinforced model was only 1/2 of that the unreinforced model. During a rare nine-degree earthquake, the X-direction inter-story displacement angle of the model strengthened with FRCM reached 1/78 and the Y-direction inter-story displacement angle reached 1/178. At this time, the reinforced model structure was destroyed, but there was no collapse of the structural components, which met the seismic design objectives of "operational under the design minor seismic intensity, repairable damage under the design seismic precautionary intensity, and collapse prevention under the design rare seismic intensity", which proved that the FRCM layer was an effective and feasible way to strengthen the existing single-story wood-masonry rural building. [ABSTRACT FROM AUTHOR]

Selecting or generating ground motions (GMs) that elicit seismic responses matching specific standards or expected benchmarks for nonlinear time‐history analysis (NLTHA) is crucial for ensuring the rationality of structural seismic design and analysis. Typical GM inputs for NLTHA, either natural or artificial, are normally spectrum‐compatible, which may produce significant variations in analysis results, even using multiple GMs. This paper introduces a response‐compatible ground motion generation (RCGMG) method for generating GMs that are tailored to be response‐compatible. NLTHA results using only a few of these artificial GMs can closely approximate the mean responses from a large set of natural spectrum‐compatible GMs or target responses. The RCGMG method adopts the response diagram in the time domain (RDTD) to characterize the nonstationary features of GMs and their impacts on structural dynamic responses. A physics‐guided conditional generative adversarial network is developed to produce artificial RDTDs with features and impacts of RDTDs of natural GMs. These generated RDTDs are then mapped into response‐compatible GMs through a feedforward neural network. To verify the effectiveness of RCGMG, NLTHA of different structure models under various site conditions and target spectra is conducted. Seismic responses of NLTHA using RCGMG‐generated GMs are compared with responses from spectrum‐compatible natural GMs. The results demonstrate that responses from RCGMG GMs are closer to the target responses, with fewer GM inputs and robust generalization performance. [ABSTRACT FROM AUTHOR]

Subjected to the coupling action of multiple hazards in hydraulic engineering, hydraulic tunnels may be corroded and damaged to varying degrees during their service lives, which will decrease the seismic performance of these structures. However, the research and seismic design of significant hydraulic engineering projects focus on investigating the structural response based on the design material parameters, which may overestimate the seismic capacity of structures during their service lives. In this paper, research is performed to identify the effect of hydro-chemo-mechanical corrosion on the seismic performance of hydraulic tunnels with different burial depths. A plastic damage model of time-varying concrete degradation induced by the hydro-chemo-mechanical effect is first determined and implemented, and the endurance time acceleration records are generated in MATLAB. Then, a study of the endurance time relationship of hydro-chemomechanical corrosion-affected hydraulic tunnels, considering the fluid-structure-surrounding rock interaction systems throughout the service period, is undertaken to directly associate the structural response with the predefined evaluation index. Moreover, this research constructs 3D time-varying fragility surfaces considering the hydro-chemo-mechanical effect and seismic intensity. The results show that the relative displacement of hydro-chemo-mechanical corrosion-affected hydraulic tunnels is larger than that of nonaffected hydraulic tunnels. Hydro-chemo-mechanical effect-induced material deterioration will lead to an increase in the cumulative damage (crack) area and damage degree of hydraulic tunnels. Additionally, the seismic fragility analysis shows that the longer the service time of hydro-chemo-mechanical corrosion-affected hydraulic tunnels, the more likely they are to collapse. Hence, attention should be given to improving the aseismic capacity of hydro-chemo-mechanical corrosion-affected hydraulic tunnels in future seismic design and performance assessments. [ABSTRACT FROM AUTHOR]

While numerous experimental tests have been conducted on single-story cross-laminated timber (CLT) shear walls, research addressing the drift performance of multistory CLT structures remains limited. This paper presents an experimental parameter study of the lateral performance of two-story platform-type CLT shear wall structures utilizing self-tapping screw connections. The test program consisted of six reversed cyclic tests investigating the impact of: (1) additional floor mass; (2) different angle bracket connections between floors; (3) different tension strap connections between floors; and (4) acoustic insulation layers on both sides of the first-level floor. The results showed that additional dead load increased the lateral resistance and that designing angle brackets to remain elastic limited the sliding contribution to total lateral deformations to less than 10%. The results also showed that the acoustic layer had minimal effect on the performance of the shear walls under the tested conditions. The tension straps significantly influenced the rocking performance, underscoring their importance to achieve similar story drifts in multistory CLT shear wall structures. Finally, while preceding single-story shear wall tests allowed designing the structures, hold-down uplifts on single-story tests were shown not to be representative for tension strap uplifts in multistory tests. [ABSTRACT FROM AUTHOR]

In designing control systems, it is known that fractional-order proportional integral derivative (FOPID) controllers often provide greater flexibility than conventional proportional integral derivative (PID) controllers. This higher level of flexibility has proven to be extremely valuable for various applications such as vibration suppression in structural engineering. In this paper, we study the optimization of FOPID controllers using twelve well-established algorithms to minimize structural responses under seismic excitations. The algorithms include crystal structure algorithm (CryStAl), stochastic paint optimizer, particle swarm optimization, krill herd, harmony search, ant colony optimization, genetic algorithm, grey wolf optimizer, Harris hawks optimization, sparrow search algorithm, hippopotamus optimization algorithm, and duck swarm algorithm. In addition to highlighting the benefits of fractional calculus in structural control, this study provides a detailed analysis of FOPID controllers as well as a brief description of the algorithms used to optimize them. To evaluate the efficiency of the proposed techniques, two building models with different numbers of stories are examined. FOPID controllers are designed based on oustaloup's approximation and the El Centro earthquake data. Using five well-known metrics, the performances of the developed methods are evaluated against five earthquake scenarios, including the recent earthquake in Turkey. A non-parametric (Friedman) test is also employed to compare the algorithms based on their corresponding vibration reduction. The findings of this analysis show that CryStAl consistently performs better than the other algorithms for both building models, thus resulting in superior vibration suppression. [ABSTRACT FROM AUTHOR]

The transition from the Uniform Building Code (UBC-97) to the International Building Code (IBC-21) marked a major shift in the definition of seismic hazard. The term "seismic hazard" in the form of peak ground acceleration (PGA) is replaced by spectral acceleration. This paper investigates the effect of using new seismic hazards on the structural performance of reinforced concrete (RC) buildings. It also looks into the financial impact on the capital costs of new buildings. Useful insights are made to understand the structural performance and financial impact of adopting IBC 21 for structural design in contrast to UBC 97. This study was carried out from the perspective of a developing country, Pakistan. Reinforced concrete moment resisting and dual frames are used as the main structural system of a typical 7-story residential building to investigate the aforementioned effect. The frames are assumed to be located in two locations with high and low seismic hazards. The effect on structural performance is investigated via nonlinear pushover analysis. Financial impact is judged mainly through cost estimation for steel and concrete. A detailed discussion is also presented on the seismic design guidelines in both codes. [ABSTRACT FROM AUTHOR]

This paper introduces a new low-damage hybrid steel–timber rocking braced frame with self-centring capability and proposes a design methodology in the framework of Canadian design standards. This system consists of a gravity load-resisting timber frame and a steel concentrically braced frame acting as the lateral load-resisting system that is connected using U-shaped steel fuses. The self-centring capability is achieved by post-tensioning strands and rocking bases within the lateral load-resisting system. The system, along with its components, is first introduced. The proposed design method and system performance objectives are then presented. The seismic performance of the system and the proposed design procedure are validated through numerical analyses considering the interaction between the lateral and gravity load-resisting systems. The results of dynamic analyses confirm the enhanced seismic performance of the proposed hybrid system with almost no residual deformations after the earthquake. Moreover, the proposed design guidelines can accurately predict the system's seismic response and demands imposed on the members. [ABSTRACT FROM AUTHOR]

An earthquake early-warning system (EEWS) is an indispensable tool for mitigating loss of life caused by earthquakes. The ability to rapidly assess the severity of an earthquake is crucial for effectively managing earthquake disasters and implementing successful risk-reduction strategies. In this regard, the utilization of an Internet of Things (IoT) network enables the real-time transmission of on-site intensity measurements. This paper introduces a novel approach based on machine-learning (ML) techniques to accurately and promptly determine earthquake intensity by analyzing the seismic activity 2 s after the onset of the p-wave. The proposed model, referred to as 2S1C1S, leverages data from a single station and a single component to evaluate earthquake intensity. The dataset employed in this study, named "INSTANCE," comprises data from the Italian National Seismic Network (INSN) via hundreds of stations. The model has been trained on a substantial dataset of 50,000 instances, which corresponds to 150,000 seismic windows of 2 s each, encompassing 3C. By effectively capturing key features from the waveform traces, the proposed model provides a reliable estimation of earthquake intensity, achieving an impressive accuracy rate of 99.05% in forecasting based on any single component from the 3C. The 2S1C1S model can be seamlessly integrated into a centralized IoT system, enabling the swift transmission of alerts to the relevant authorities for prompt response and action. Additionally, a comprehensive comparison is conducted between the results obtained from the 2S1C1S method and those derived from the conventional manual solution method, which is considered the benchmark. The experimental results demonstrate that the proposed 2S1C1S model, employing extreme gradient boosting (XGB), surpasses several ML benchmarks in accurately determining earthquake intensity, thus highlighting the effectiveness of this methodology for earthquake early-warning systems (EEWSs). [ABSTRACT FROM AUTHOR]

The new generation of China Railway Track System III (CRTS III) ballastless track structure has been found vulnerable under high-level earthquakes. However, the seismic characteristics and the damage mechanism had not been well studied. In this paper, a 4-span high-speed railway (HSR) simply supported bridge-track system model is established to investigate the seismic response and damage mechanism of the bridge-CRTS III slab ballastless track system under transverse earthquakes by nonlinear history analysis. In accordance with the results, the piers have a good seismic performance under high-level earthquake (0.57 g). The non-uniform vibration of unequal-height piers results millimeter-level inconsistent displacements between the girders. The fixed bearing is vulnerable under the earthquakes with PGA of 0.3 g and 0.57 g, indicating that the seismic design of fixed bearing should be optimized to enhance the seismic resistance under high-intensity earthquake. After the damage of fixed bearing, the friction is not enough to pull the girders to vibrate together with piers which leads the sliding of girders. The sliding of girder exacerbates the non-uniform displacements of girders and roadbed. The non-uniform vibration and residual slips of girders lead deformation of the rail, especially forming turning angles at the girder joints which may impact the safety of train operation. [ABSTRACT FROM AUTHOR]

Near-fault ground motions (NFGM) may have a significant component of the long period velocity pulse (LPVP) due to the directivity effect. The structures subjected to such ground motions are prone to experience large displacements. In this paper, the damage potential of such motions is compared with NFGM (without LPVP) and far-field motions in terms of seismic demand (inter-storey drift and inelastic displacement). Due to the lack of site-specific recorded NFGM, the synthetic ground motions are generated and used in this study. For this purpose, first the bedrock motions are obtained through stochastic simulation approach in which the Specific Barrier Model (SBM) is used as source spectrum and then these motions are transferred to the ground surface using one-dimensional ground response analysis. In order to obtain the NFGM with pulse, the bedrock motions are superimposed with the LPVPs and then transferred to the ground surface. To illustrate, the case of a ten-storey reinforced concrete (RC) building is considered in Delhi region (India) which falls under the seismic zone-IV. The main finding of this study is the observation that the NFGM with LPVP impose almost double seismic demand compared to the NFGM without LPVP, specially for the structures lying in the velocity-region of the response spectrum. In this study, the effect of depth of bedrock on seismic demand is highlighted and recommended to be included in the design seismic demand of NFGM. [ABSTRACT FROM AUTHOR]

Steel side-plate connections are reliable load path alternatives because they eliminate the fabrication challenges associated with continuity plates, especially for concrete-filled tubes (CFTs). In this paper, a new easy-to-fabricate moment connection for connecting I-beams to CFT columns using the monolithic side-plate technique is proposed. In this connection, the vertical side plates are entirely replaced by column webs to save steel material by eliminating the use of double steel plates in the connection panel zone and resolving the biaxial fabrication issues associated with the lack of welding access between the orthogonal side plates and the column. Four full-scale experimental tests consisting of two couples of relatively identical bolted and welded connections were conducted under a cyclic lateral displacement control loading protocol and a constant compressive axial load was applied to the column to evaluate the seismic performance of the connection. Furthermore, standard geometrical limitations, such as the column width and beam depth, were challenged. The results indicated that the new proposed connection exhibits sufficient stiffness and high level of ductility up to more than 4% of story drift without any strength degradation, implying that this new connection can be classified as a prequalified rigid moment connection to be used in special moment frames (SMFs) located in high seismic regions. In this paper, a monolithic side-plate connection is proposed and four full-scale specimens with oversized geometrical characteristics are experimentally investigated. The favorable results of this study show that this connection can be used as a prequalified rigid beam-to-column moment connection in intermediate and special steel moment frames consisting of box columns. The proposed easy-to-implement connection offers advantages such as decreased weight, fewer welding operations, and biaxial connection capability, which are not possible with conventional side plates. This connection is successfully implemented in an IMAX multicomplex building, with 151,676 m2 gross area and 82.32 m height. The proposed idea is applicable to any project with large box-shaped columns in high seismic regions and the achievements of this study can provide experimental support for the seismic design of these buildings. Critical factors in the connection performance are the column width and side-plate geometry, and considering other specific aspects of this connection, there is a lot of potential for further numerical and experimental investigations. Although not shown in this work, the proposed approach gives us the necessary flexibility to easily develop a biaxial moment connection, and further research is recommended in this case. [ABSTRACT FROM AUTHOR]

The 2010–2011 Canterbury earthquake sequence highlighted the vulnerability of New Zealand light-frame wood buildings that are the predominant typology in residential construction. While life-safety performance was excellent, many buildings experienced widespread cracking of internal wall linings that resulted in costly repairs and disruption. Despite the widespread use of light-frame wood construction in New Zealand, no known shake table tests have been documented for this construction typology. Additionally, New Zealand light-frame wood building performance cannot simply be inferred from international testing because New Zealand adopts a different design philosophy from those of the US and Canada by relying on gypsum sheathing as the primary lateral resisting element. To further investigate New Zealand light-frame wood building performance, this paper discusses shake table testing of a light-frame wood building specimen, constructed on the University of Canterbury unidirectional shake table using modern New Zealand design and construction approaches. The observed damages during the tests were consistent with those observed in similarly built structures that were investigated after the 2010–2011 Canterbury earthquake sequence. This paper also presents a modeling approach using the state-of-the-art software Timber3D, which was verified by simulating the shake table specimen and comparing the observed and predicted dynamic response from the test specimen and model, respectively. The Timber3D modeling approach included analysis and parameterization of screw-slip data using the Evolutionary Parameter Hysteretic Model, formulation of two-dimensional wall component models, and nonlinear time history analysis of a three-dimensional model of the shake table specimen. The model was shown to reasonably predict the displacement response of the shake table specimen and the strength degradation from cracking damage through repeated earthquakes. The modeling approach described is intended to further the development of residential building models toward the performance-based seismic design of light-frame wood buildings in New Zealand. [ABSTRACT FROM AUTHOR]

Shallow-buried cavities and underground structures are inevitably subjected to transient perturbation from earthquakes or engineering activities during their life circle, leading to the occurrence of dynamic failure. The investigation presented by this paper concentrates on the dynamic responses triggered by an aperiodic transient P wave around a circular lined tunnel with an imperfect interface in a half-space and the spring model is employed to describe the interface between rock mass and liner. Resorting to the wave function expansion scheme, the large arc assumption, the Graf's addition theorem and the numerical inversion algorithm of Laplace transformation, the dynamic responses around a circular shallow lined tunnel with an imperfect interface are evaluated theoretically. The good agreement of time–history curves and contour snapshots for stress between the theoretical solutions and the numerical counterparts validates the analytical scheme. The effect of disturbance direction, embedment depth, thickness of liner and interface coefficients on the dynamic responses around the shallow-buried lined tunnel is analyzed. The results indicate that the positions of peak hoop dynamic stress concentration factor (DSCF) are approximately perpendicular to the perturbation direction. The DSCF distributions converge to be stable when the ratio of embedment depth to excavation radius exceeds 10.0. The thickness of the liner mainly affects the dynamic responses around the interface. Increase of elastic coefficient induces a decreasing DSCF in rock mass and an increasing counterpart in the liner. The results may provide the theoretical basis for the transient responses and aseismic design of underground tunnels. [ABSTRACT FROM AUTHOR]

This paper aims to evaluate the seismic response of multitiered buckling-restrained braced frames (MT-BRBFs), assess the design provisions specified by the 2022 AISC Seismic Provisions for multitiered BRBFs, and propose improvements to these provisions. A set of 17 frames is first selected by varying bracing configuration, frame height, number of tiers, and tier height ratio. The frames are then designed in accordance with the 2010 and 2022 AISC Seismic Provisions. A numerical parametric study is performed under scaled ground motion accelerations. The results of the parametric study show that when the frames are designed to the 2010 provisions, the frame inelastic deformation tends to concentrate in the tier(s) undergoing tensile yielding due to their lower postyield stiffness, compared to BRBs yielding in compression, which creates unequal story shear, contributed by braces, in adjacent tiers with BRBs in tension and compression and engages column flexure to compensate for unbalanced brace story shears between tiers. Columns experience yielding and even buckling in several cases due to combined flexural and axial load demands. MT-BRBFs designed to the 2022 AISC Seismic Provisions exhibit a more uniform deformation response between tiers and relatively lower flexural demands in their columns. However, these provisions may overestimate column in-plane flexural demands (on the order of 3), resulting in potentially uneconomical design solutions. On the basis of the numerical simulations, modifications are proposed to compression BRBs' adjusted strength to better estimate column in-plane flexure and tier deformation while achieving an economical column design. The proposed improvements are validated using dynamic analyses. [ABSTRACT FROM AUTHOR]

This paper presents an extensive numerical study on the seismic performance of steel eccentrically braced frames (EBFs) designed according to the ASCE 7-16 standard. A series of EBF building structures ranging from 2 to 12 stories located in downtown Los Angeles are designed with different yielding links, including conventional and replaceable links. The performance of the structures is investigated through nonlinear time-history analyses (NLTHAs) under a suite of 40 ground motions, selected and scaled to match the target uniform hazard spectrum. The peak deformations are first examined to assess the performance of the buildings as well as the design procedure. Residual deformations are also evaluated and critically compared with acceptable limits, to provide insight into the downtime and recovery time of EBFs after major earthquakes. Previous studies have demonstrated that the response of stable yielding systems to major earthquakes is often accompanied by significant residual deformations, and that residual drifts exceeding 0.5% can cause hindrance to the buildings occupants. In EBFs, in addition to residual drifts, residual link rotations are also relevant and expected to be more severe due to the localization of inelastic deformations in the yielding link. For replaceable modular yielding links, significant residual link rotations after major earthquakes will hinder repairs and the link replacement process, which is one of the important design objectives. The performance of EBFs is also compared with what was observed in previous studies for buckling restrained braced frames and special moment resisting frames. In the end, the results from the extensive NLTHAs are used to establish a relationship between peak drifts and peak link rotations in EBFs. [ABSTRACT FROM AUTHOR]

Shape memory alloys (SMAs) show great potential in self-centering structures because of their appealing superelastic feature and good energy dissipation capability. The mechanical properties of SMA bars have been extensively studied over the past decades. However, the characteristics of smooth surface and poor machinability of the SMA bars, especially the widely used nickel–titanium SMAs, bring challenges to the anchorage systems in practical applications. This existing limitation is especially prominent for SMA bars designed to be used at the critical deformation locations of structural members or in seismic devices experiencing extreme working conditions. For this reason, this paper develops a novel hybrid threaded-swaged anchorage system to overcome the limitations of the current SMA mechanical splices. The uniaxial behavior of the threaded-swaged anchorage systems under different loading conditions was investigated experimentally with emphasis on the seismic application-oriented responses. Furthermore, the influence of eccentricity on the anchorage system was also considered to evaluate the SMA bars with large end rotation induced by the rocking behavior of the self-centering structures during earthquake shaking. Test results reveal that the performance of the proposed anchorage system is satisfactory with stable behavior under different loading conditions, which can provide a promising anchorage solution for SMA bars used in seismic resilient design. Moreover, a practical design method for this anchorage system is proposed for implementation in seismic applications. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the dynamic response characteristics of subway station under earthquakes. To this end, seismic waves are transformed into equivalent nodal loads on viscoelastic artificial boundaries using theories and methods of wave motion. The calculation formulas for equivalent nodal loads of SV waves incident at any angle are established, and ANSYS' APDL program compiles to automatically generate the viscoelastic artificial boundary and input the seismic loads. A finite element model of soil-subway station interaction was established, and the seismic response characteristics of a two-story three-span subway station under different incidence angles of SV waves were investigated using the above seismic input method. The results indicate that the incidence angle of seismic waves has a significant impact on the seismic response of subway station. Inclined incidence of seismic waves causes non-uniform loading and deformation of the subway station. Specifically, a small angle leads to predominantly transverse shear deformation, while a large angle causes mainly vertical shear deformation. The inclined incidence of seismic waves significantly increases the vertical acceleration of the subway station, with the effect becoming more pronounced as the angle increases. Additionally, special attention should be given to the joints between the structural slab and the side wall, slab and center column, as well as the two ends of the center column as they are vulnerable areas during earthquakes and require careful consideration in seismic design. [ABSTRACT FROM AUTHOR]

With the development of building seismic isolation technology and the official release of the Isolation Code in September 2021, seismic isolation design in China will now rely on two foundational codes: the Seismic Code and the Isolation Code. This paper take a ceramic jar storage of the RC frame structure as the research object, and carry out the seismic isolation design based on the separated calculation design method of the Seismic Code and the unitary calculation design method of the Isolation Code respectively, and clarify the control index of the Isolation Code is the story drift angle. The maximum displacement is reduced by 37.5%. In terms of material consumption, the Isolation Code leads to a 5.94% decrease in concrete usage, accompanied by a 13.97% increase in steel consumption, resulting in an overall cost increase of 4.98%. The findings indicate that seismic isolation design, guided by the Isolation Code, substantially mitigates the seismic response of the superstructure. The damage extent to structural members is reduced by 15–20%, promoting enhanced safety and repairability. The outcomes of this study offer valuable insights for future seismic isolation designs in RC frame structures. [ABSTRACT FROM AUTHOR]

Particle tuned mass damper has received considerable attention on mitigating structural seismic responses recently. However, soil-structure interaction effects have not been considered for the optimization design of particle tuned mass damper in the previous studies yet, which may play significant roles in particle tuned mass damper's effectiveness. This paper investigates the seismic control performance of particle tuned mass damper for tall buildings considering SSI effects. A 40-story benchmark structure is adopted as the primary structure, and different soil conditions including soft, medium, dense soil, and the fixed-base case are considered. Based on the Cuckoo Search algorithm, an optimum design approach for the particle tuned mass damper implemented in SSI system under earthquake excitations is proposed, and the optimum parameters of particle tuned mass damper are obtained from the optimum design process. The optimum results indicate that the optimized particle tuned mass damper can effectively decrease the displacement response without the increase of peak acceleration, and the reduction rates could exceed 30% in some cases. Compared with other soil type cases, under soft soil condition, the optimum parameters of particle tuned mass damper are especially different, and the mitigation effects of the optimized particle tuned mass damper on maximum displacement weaken. Hence, it is necessary to consider the SSI effects for particle tuned mass damper's seismic design. Furthermore, the interaction effects between the primary structure and particle tuned mass damper in SSI system are also evaluated through energy analysis. The results show that considering SSI effects, the optimized particle tuned mass damper device dissipates the overwhelming majority of the input energy, and it greatly decreases the structural energy, displaying excellent energy dissipation performance on seismic vibration control of structure. [ABSTRACT FROM AUTHOR]

A variety of self-centering devices and structural systems have been proposed and investigated in recent years to eliminate or reduce postearthquake repair, but so far their applications are still very limited. This paper reports the seismic resilience enhancement of an irregular space structure by using friction-damped self-centering tension braces (FSTBs). First, the configuration, performance, and numerical model of FSTBs are introduced, and then a seismic design procedure for enhancing the seismic capacity of a torsional irregular structure is proposed. Taking the terminal building at the Harare Airport, a lifeline project in Zimbabwe, for example, unidirectional and three-dimensional nonlinear dynamic analyses were conducted on the building designed with and without FSTBs. The result shows that FSTBs can significantly reduce both story drifts and residual story drifts of the bottom reinforced concrete frame and displacements of the steel roof. To this end, the field assembly of FSTBs is briefly reported. The presented study provides references to the use of self-centering devices in seismic resilience upgrades of important engineering projects. [ABSTRACT FROM AUTHOR]

The composite pier, which consists of ultra-high-performance concrete (UHPC) and normal strength concrete (NSC), is a promising option for practical engineering due to its remarkable mechanical performance. However, the cyclic behavior and seismic design mechanism of the composite pier have not been thoroughly investigated. This paper aims to study the cyclic performance of the composite pier by conducting cyclic tests on 10 specimens. The thickness of the UHPC tube, strength of reinforcement, spacing of stirrups, and other parameters are considered. The crack distribution, hysteretic response, and failure modes are observed and analyzed. Results show that the composite pier exhibits good crack-control ability, large bearing capacity, and effective energy dissipation. The expansion of the inner NSC may exacerbate the buckling of the UHPC tube, thus leading to more severe seismic damage. To further investigate the composite pier, a numerical model is established to analyze the optimal thickness of the UHPC tube. The ultimate state of the composite section is taken into consideration, and the upper and lower limits of the height of the compression zone are proposed. Based on the parametric analysis, a recommended range of the UHPC tube thickness is derived. [ABSTRACT FROM AUTHOR]

Steel multitiered concentrically braced frames (MT-CBFs) not specifically detailed for seismic resistance with a response modification factor of R=3 are permitted in moderate seismic regions. Past research studies, however, have raised concerns regarding the seismic performance of MT-CBFs and CBFs designed using R=3 provisions, namely the stability of columns in MT-CBFs and connection limit states in R=3 CBFs. This paper examines the seismic response of R=3 MT-CBFs and proposes a design method to improve their seismic performance. A set of 16 prototype R=3 MT-CBFs, ranging from 8 to 20 m tall with two to five tiers and located in a moderate seismic area, was selected and designed in accordance with 2016 US design guidelines. Nonlinear response-history analyses were then performed to examine the seismic response of these frames using fiber-based numerical models. R=3 MT-CBFs designed to 2016 design guidelines are shown to experience premature fracture in brace-to-beam/column connections in a single tier, which imposes high in-plane bending demands on columns and in some cases, leads to column instability or a tier-sway mechanism. New seismic design recommendations, including requirements for intermediate struts, columns, and tier drift, are proposed. The design method aims to prevent column instability or a tier-sway mechanism and protect brace connections from excessive deformation. [ABSTRACT FROM AUTHOR]

Seismic-resistant design incorporates measures to ensure that structures perform adequately under specific limit states, focusing on seismic forces derived from both the equivalent static and spectral modal methods. This study examined buildings on slopes in densely built urban areas, a common scenario in Latin American cities with high seismic risks. The adjustment of high-rise buildings to sloping terrains induces structural asymmetry, leading to plan and elevation irregularities that significantly impact their seismic response. This paper explores the asymmetry in medium-height reinforced concrete frame buildings on variable inclines (0°, 15°, 30°, and 45°) and its effect on their nonlinear response, assessed via displacements, rotations, and damage. Synthetic accelerograms matched with Chile's high seismic hazard design spectrum, scaled for different performance states and seismic records from the Chilean subduction zone, were applied. The findings highlight structural asymmetry's role in influencing nonlinear response parameters such as ductility, transient interstory drifts, and roof rotations, and uncover element demand distributions surpassing conventional analysis and in earthquake-resistant design expectations. [ABSTRACT FROM AUTHOR]

Base dual-mechanism systems that limit both shear force and overturning moment demands are being developed as a new class of seismic force–resisting systems to enhance the control of seismic demands at the base and along the height of tall buildings and to control higher-mode effects. Despite an increasing number of numerical studies that demonstrate the enhanced seismic resilience of tall buildings as a result of better-controlled shear force and overturning moment demands and reduced higher-mode effects through a variety of base dual-mechanism configurations, there are limited design methodologies for buildings with this type of seismic-resistant base system. This paper proposes a simplified method for the performance-based seismic design methodology for these base dual-mechanism systems and the structures above, which consists of (1) designing the dual base-mechanism system using a set of design charts, and (2) protecting the rest of the structure for the maximum expected seismic force demands computed using closed-form equations. The proposed method was used in this paper for the preliminary design of four example core-wall tall buildings with heights of 45, 90, 150, and 300 m. The adequacy of the proposed method was demonstrated using three-dimensional finite-element models. The analysis results were in reasonable agreement with the targeted force and displacement demands estimated using the proposed simplified method for the preliminary design of dual base-mechanism systems. [ABSTRACT FROM AUTHOR]

A reliable assessment of earthquake-induced permanent displacements is a fundamental step for both displacement-based and force-based methods applied to the seismic design of embedded anchored walls. Acceleration reduction factors recommended by the codes for a force-based design of these structures derive from parametric studies of the performance of gravity walls or slopes. This may lead to either conservative or unconservative results and is certainly misleading from the point of view of the physics of the problem. Based on the results of an extensive numerical study, this work clarifies the mechanisms by which anchored walls accumulate permanent displacements during earthquakes, showing that full mobilization of soil passive strength requires displacements of the order ur/H≈1%–2% , making the assumption of rigid-perfectly plastic behavior of the system unsuitable. Moreover, both the critical acceleration and the pattern of final displacements depend on the plastic mechanism effectively activated within the soil-wall-anchor system. The issue of the proper choice of performance factors to be used in a force-based design of anchored walls is also addressed, and a new method is outlined for a preliminary calculation of the permanent displacements of the wall. Finally, the paper critically reviews two methods recently proposed in the literature to compute earthquake-induced wall displacements. All three methods account for the soil-wall system nonlinearity and hardening during the earthquake. The results discussed herein, together with the complementary work presented by the same authors in a companion paper, provide a thorough conceptual framework for the performance-based seismic design of anchored walls. [ABSTRACT FROM AUTHOR]

This document is a compilation of various research papers and abstracts related to seismic activity and earthquake research in Croatia and Hungary. The papers cover topics such as seismic site amplification, site response analysis, local site effects, lithosphere structure, gravity anomaly models, and seismic performance assessment of buildings. The research provides valuable insights into earthquake risk and mitigation strategies in the region. The document also includes links to additional information and resources for further exploration. [Extracted from the article]

Ductile end diaphragms have been suggested as an appropriate device in the past to improve the seismic response of steel girder bridges. This paper investigates the efficiency of the seismic design strategy that utilized a slab-connected steel plate as a ductile diaphragm in the superstructure. Protecting the main girder from typically reported damage and mitigating the transferred lateral load to the non-ductile substructures are the main objectives of this study. The results show that a slab-connected thin steel plate with low yielding stress (LYS) can mitigate the force demand on the non-ductile substructures and act as a structural fuse. It can also reduce the transverse displacement of the superstructure and, consequently, prevent the end of the main girder from buckling and/or yielding. [ABSTRACT FROM AUTHOR]

While the use of cross-laminated timber (CLT) panels for building construction has increased over the last several decades, current standards and existing literature provide limited information regarding the design of CLT diaphragms or the prediction of their deflections when subjected to wind and strong earthquake motions. This paper presents the design and assessment of a CLT diaphragm that was part of a full-scale two-story structure subjected to shake-table testing. An analytical model is proposed for diaphragm deflection accounting for in-plane shear and bending stiffness, as well as the stiffness of various connections. Moreover, a refined numerical modeling strategy is proposed in order to consider phenomena such as panel-to-panel gap closure. Results indicate that the analytical model yields conservative results both in terms of deflections and forces when compared to the numerical model that simulates similar sources of strength and stiffness. The analytical model is suitable for the design of symmetric diaphragms with regular shapes, whereas the numerical model can also be used to model asymmetric diaphragms with irregular shapes. [ABSTRACT FROM AUTHOR]

This paper focuses on the seismic response of symmetrical underground subway stations to seismic waves with varying frequencies and peak ground accelerations (PGAs), essential in light of growing urban underground transit systems. A 1/40 scale station model was subjected to seismic simulations using waves from the Wenchuan and Tangshan earthquakes and an artificial wave spanning 0.1 g to 0.5 g PGAs. Shaking table tests revealed that seismic impacts divide at PGA = 0.3 g; high-frequency waves affect structures more below this threshold, while low-frequency waves have more impact above it. The columns on the third basement level responded more to seismic activity, particularly at their base. The study recommends prioritizing the seismic design of these columns during station construction, especially in earthquake-prone zones. Understanding the dynamic effects of different frequencies and amplitudes is crucial for selecting and reinforcing materials and structural designs to enhance seismic resistance. [ABSTRACT FROM AUTHOR]

This paper presents experimental investigations on the lateral performance of cross-laminated timber (CLT) shear walls with customized self-tapping screw (STS) connections. The panel-to-base (hold-downs and shear brackets) and panel-to-panel (spline) connections were tested under quasi-static monotonic and reversed cyclic loading to derive design values of STS, which were shown to be 2.8–3.6 times higher than those calculated using the current Canadian timber design standard. Then, a total of 26 CLT shear walls, including single-, double- and triple-panel configurations, were tested, again under quasi-static monotonic and reversed cyclic loading. The shear walls consisted of five-ply, 139-mm-thick and 3-m-high CLT panels with aspect ratio of either 2∶1 or 3∶1 , and different numbers of STS in the connections. The shear wall strength and corresponding displacements increased with the number of screws in hold-downs and spline joints; further, it increased with number of connected panels and decreased as a function of aspect ratio. The data can be used for developing and calibrating numerical models to investigate the lateral responses of CLT shear walls with different configurations. [ABSTRACT FROM AUTHOR]

The establishment of secure earth-independent long-term lunar habitats has been envisioned by numerous government agencies and private companies. Recent advancements in assessing seismic hazards caused by shallow moonquakes have highlighted the importance of incorporating this phenomenon into the design of robust and resilient lunar structures. However, further research is required to explore lunar habitat design that considers seismic loads. This paper proposes assessing the structural response of a lunar habitat made of sulfur concrete covered with a regolith layer. The numerical model of the structure is subjected to gravitational, internal pressure and seismic loads. The seismic analysis of the structure is carried out using spectral and nonlinear time history methods. Conditional mean spectra for shallow moonquakes with return periods of 75, 475, 970 and 2475 years are used in the seismic analysis. The records used for the temporal analyses were ground motions that agree with a preliminary seismic hazard on the Moon. The results of temporal analyses reveal that shallow moonquakes with return periods greater than 475 years can lead to the loss of the global stability of the structure. Consequently, the findings imply that seismic loads have the potential to impose unacceptable demands on lunar structures constructed from in-situ materials like sulfur concrete. Hence, it is imperative to incorporate seismic considerations in the design process for developing resilient and long-term lunar habitats. • Seismic analysis of a lunar structure was carried out using spectral and temporal methods. • A methodology was adapted to scale moonquake records to different hazard spectra obtained from probabilistic methods. • It was demonstrated that seismic demand might generate unacceptable deformations in lunar structures built with in-situ materials. [ABSTRACT FROM AUTHOR]

In response to the increasing need for sustainable construction materials, numerous innovative timber-based structural systems have been developed in the past two decades. While timber-based shear-walls are popular, moment-resisting timber frames have received less attention in recent studies. However, with the availability of ductile and resilient beam-column joints (BCJs), timber frames can now be effectively used either independently or in combination with others. This study explores the feasibility of a dual system, consisting of cross-laminated timber (CLT) balloon shear-wall and glulam moment-resisting frame (CLTW-GMRF), and investigates the potential interaction between the two systems under seismic loading. The building features ductile and energy-dissipative BCJs and hold-downs. A seismic design procedure, based on a targeted moment proportion (MP) between the two systems, is presented and applied on a 10-story building. The building is assumed to be located in Vancouver, Canada, and its seismic performance is examined using 30 ground motion records in OpenSees. The system's efficiency with respect to engineering demand parameters is studied under different wall-to-frame MP values (50%–50% and 60%–40%) and ductility-related modification factors (2, 3, and 4). The study also investigates the system's performance with two BCJs and hold-down alternatives with bilinear hysteretic and self-centering energy-dissipative responses. Given the availability of resilient connections, the result highlights that the CLTW-GMRF coupled system is a viable alternative for high-rise hybrid timber construction. Moreover, the system's performance has significantly improved by using self-centering energy-dissipative systems. This paper unveils an innovative design approach and practical application for a CLTW-GMRF dual system. This innovative system incorporates energy-dissipative components that are designed and tested in existing literature: (1) the utilization of replaceable steel damper BCJs and buckling-restrained brace hold-downs, providing high ductility with large energy-dissipative capacity; and (2) the employment of hybrid BCJs made up of post-tensioned tendons and mild steel dissipators, along with hybrid brace hold-downs made up of pretensioned tendons and friction surfaces, which reduce residual deformations following seismic events. Utilizing these systems, the research introduces a versatile seismic design method congruent with existing codes and design standards, while offering flexibility through adjustable wall-to-frame moment proportions. The research also underlines the need for careful consideration of the interaction within the timber wall-frame systems. The implications are substantial amidst the growing trend of high-rise timber construction, aiming to fully exploit the potential of CLT and Glulam frames. Moreover, the research has the potential to serve as an essential resource for engineers aiming to optimize the sustainability and resilience of timber structures, particularly in seismic-prone regions. [ABSTRACT FROM AUTHOR]

This paper presents the experimental results of two welded unreinforced flange-welded web (WUF-W) beam-to-column connections that defy the current design paradigm of prequalified welded connections. The proposed WUF-W connections feature customized beveled backing bars that are intentionally left in place after the completion of the beam flange-to-column face complete joint penetration welds. The connection design aims at a stable hysteretic response by exploiting the beneficial aspects of appreciable panel zone shear yielding (i.e., inelastic shear distortions of at least 15γy , where γy is the panel zone shear distortion at yield), by considering a shear strength-to-demand ratio of 0.8. To prevent divot fracture in the column, minimum through-thickness toughness requirements were imposed for the steel column material. The experimental results suggest that the proposed WUF-W connections achieve a stable hysteretic response up until lateral drift demands of at least 7% rad, while a non-softening response was assured up to 9% rad. The beveled backing bars minimize the associated fracture potential near the beam web centerline, which is a primary concern in prequalified field welded moment connections when conventional weld backing bars are employed. The tests suggest that, under a symmetric cyclic loading protocol, local buckling near the steel beams is prevented up until a lateral drift demand of 6% rad, which is an important finding from structural repairability and stability standpoints. The ultimate failure modes of the welded connections, which are attributable to ductile crack initiation and propagation, are consistent regardless of the employed lateral loading histories, which involved standard symmetric cyclic and collapse-consistent loading protocols. The implications for the seismic design of steel moment resisting frames (MRFs) and the limitations of the present work are discussed. [ABSTRACT FROM AUTHOR]

This paper investigates the feasibility of employing timber pegged joints in modern seismic-resistant structures or for retrofitting existing structures. The behavior of timber pegged connections has been investigated for about twenty years, but seismic design aspects are not treated in existing standards. In the framework of the force-based design approach, this paper analyzes and defines seismic design aspects and rules for timber pegged connections that are easy-to-use in engineering practice. A large database (more than 350 test results) has been elaborated and the data processed with the purpose of (1) analyzing the effectiveness of the European Yield Model for evaluating the maximum strength of the connection, accounting for the particular embedding behavior due to the presence of timber peg; (2) assessing and defining the capacity design rules to design the dissipative regions (i.e., overstrength factor); and (3) defining the available ductility of the connection with identification of ductility class intervals. The obtained results proved that timber pegged joints have a good potential to be used in seismic-resistant structures. In fact, data processing identified a suitable value for the overstrength factor (useful to project the joint with the capacity design) similar to that used for steel-dowelled connections, and defined a likelihood range of ductility classes. Finally, it is highlighted that the European Yield Model can be a practical tool to calculate connection strength, provided that some modifications are included to consider peg behavior. [ABSTRACT FROM AUTHOR]

Mixed multiple seismic systems (MMSSs) are ideally suited for sustainable seismic design (SSD). MMSSs are combinations of two or more different earthquake-resisting structures (ERSs) that provide lateral support for gravity frameworks. Same-system combinations have been demonstrated to not be suitable for SSD. Regardless of the carbon footprint reduction, unless a structure has been designed for seismic sustainability it would be disposable with greater harm to the environment. Here, design means planning for both seismic resistance as well as post-earthquake realignment and repair (PERR). Earthquakes are random, natural, and dynamic events, whereas PERR is a deliberate, manual, and static process. In SSD the practicality of PERR is as important as the relevance of the theoretical assumptions. In SSD the non-lateral-resisting items are designed not to partake in seismic resistance, nor hinder the realignment process. Additionally, efforts are made to mitigate the P -delta effects that undermine the global strength of the system and oppose the recentering effort. The purpose of this paper is to identify and remedy design flaws and physical issues that prevent MMSSs from achieving seismic sustainability as cost-effectively as possible. Two newly developed technologies, the ladder moment frame (LMF), and the fail-safe (FS) system, as well as a capacity distribution rule together with six simple axioms are introduced. Brief descriptions of LMF and FS are presented in the text. Any structure designed to survive earthquakes is expected to either remain elastic and stable or be capable of post-earthquake realignment and repairs. Sustainable seismic design is a new field of research that promises improved environmental conditions and innovative developments in structural engineering. Regardless of the carbon footprint reduction, unless a structure has been designed for the purpose, it would be disposable with greater harm to the environment. Here, design implies planning for seismic resistance as well as post-earthquake realignment and repairs. The difference between conventional and sustainable seismic design is in the modes of behavior during and after the event. In conventional seismic design, the object is to satisfy code-specified requirements; in sustainable seismic design, the post-earthquake attributes of the system are as important as those during the event. The paper shows that seismic sustainability can be achieved without resorting to untenable costs and technologies. In light of current findings, it is suggested to include post-earthquake realignment and repairs in seismic design guidelines for new construction. [ABSTRACT FROM AUTHOR]

Horizontal to vertical spectral ratio (HVSR) based on seismic ground motion is an important index to study site conditions and dynamic characteristics (seismic effect). Due to the influence of the vertical dynamic amplification effect of the site, the Fourier spectral ratio calculated according to the surface motion and downhole motion is quite different from that of the horizontal and vertical ground motion in the case of strong vibration input. However, our recent research shows that when considering the time-varying characteristics of ground motion, the time-varying surface-downhole spectral ratio and time-varying HVSR are almost the same. Based on this discovery, the time-varying HVSR is used to study the dynamic characteristics of the site (site effect). First, a new method for calculating the natural period and damping ratio of the site is proposed. Secondly, based on tremendous strong motion records, the prediction formulas of natural period and damping ratio are studied. Finally, the effects of various influencing factors on the natural period and damping ratio are compared. The results of this paper can provide a basis for selecting and synthesizing appropriate ground motions in structural seismic design. [ABSTRACT FROM AUTHOR]

Determining the characteristic period of ground motions (Tg) is an essential step in the seismic design of structures, but a critical problem that needs to be solved is figuring out how to do so when bedrock ground motion is utilized as an input. In this paper, the relationship between surface and borehole temperature data is investigated, and the main factors affecting the Tg are analyzed. Then, the algorithm for predicting Tg is presented. It is found that two factors, i.e., peak ground acceleration (PGA) and fault distance have significant effects on the value of Tg. By comparing the values of Tg for borehole and surface motions, we find that, contrary to expectation, Tg for borehole motions is usually larger than that for surface motions in most cases. Finally, the conversion equation between the Tg for borehole and surface motions is given using regression analysis. [ABSTRACT FROM AUTHOR]

Assessing the nonlinearity of a site plays a crucial role in earthquake engineering. For some building structures and lifeline projects that need safety assessment after earthquakes, the analysis of nonlinear degree of sites can help accurately revealing the amplification effect of sites and evaluating the damage degree of buildings which is convenient for subsequent reinforcement and demolition work. The quantitation of nonlinear threshold of sites is an important method to evaluate the degree of site nonlinearity. In this paper, a nonlinear characteristic index reflecting the degradation of shear modulus is proposed based on the instantaneous frequency of the site calculated by using the vector auto-regression moving average (VARMA) model. Then, seismic records of class I, II, III and IV sites specified as per code for seismic design of buildings in China are selected from the KiK-net network in Japan, and the threshold value of ground motion acceleration characterizing the nonlinear response of sites are provided. Finally, the variation of the nonlinear characteristic index (shear modulus degradation) vs. different (peak ground acceleration) PGA for four types of sites are presented. [ABSTRACT FROM AUTHOR]

Precast concrete (PC) structures have many advantages, but their use in the construction of middle- to high-rise buildings is limited. The construction of PC structures requires skills in various operations such as transportation, assembly, lifting, and structural soundness. In particular, regarding the seismic design of PC structures, it is necessary to clearly evaluate whether they have the same structural performance and usability as integral RC (cast-in-place) structures. In this paper, an experimental study was conducted to investigate whether PC members can achieve a seismic performance equivalent to that of RC members in beam–column joints, which are representative moment-resisting frames. The main variables are the two types of structural systems (intermediate and special moment-resisting frames) and the design flexural strength ratio of the columns and beams. The experimental and analytical results showed that the seismic performance of the PC specimens was equivalent to that of the RC specimens in terms of strength, stiffness, energy dissipation, and strain distribution, except for the specimen with splice sleeve bond failure of the column reinforcement (poor filling of the internal mortar). In addition, the I series satisfied the present emulation evaluation criteria for special moment-resisting frames of PC structures, confirming the possibility of applying intermediate moment-resisting frames. [ABSTRACT FROM AUTHOR]

With the rapid development of urbanization, high‐rise buildings have risen from the ground, but in the long‐term use of the building, there will be settlement, tilt, displacement, and other deformations, which will seriously bring disasters. At present, there is a lack of an application‐level settlement monitoring system for the monitoring of these buildings, and there are problems of low intelligent monitoring level and low monitoring accuracy, so this paper proposes a double‐loop monitoring system based on laser collimation. The system combines distributed computing, spot image processing, embedded computing, laser collimation technology etc., to design settlement monitoring equipment and corresponding software. Finally, the data processing is carried out by the double‐loop calculation algorithm to obtain the sedimentation amount of the analyte. The test results show that the whole system can be intelligently and accurately monitored, and the monitoring accuracy can reach the millimetre level. [ABSTRACT FROM AUTHOR]

The current paper's goal is to investigate how dynamic interaction phenomena and material nonlinearities affect the dynamic behavior of a concrete gravity multi-arch dam in terms of maximum displacements, natural stresses, principal stresses, and Von Mises stresses when subjected to seismic excitation. Utilizing ANSYS APDL software, linear and nonlinear transient analysis using the finite element method was employed to analyze the interaction between the dam and its rock foundation. As a case study for this work, the multiarch Beni-Bahdel dam was selected, and the seismic excitation used data from a simulated earthquake. The direct method is employed to model the interaction between the multi arch dam and the rock foundation using two approaches; the fixed base approach and the mass foundation approach. Six finite element models were performed using ANSYS code, "linear dam-fixed support", "nonlinear dam- fixed support", "linear dam-linear rock foundation" "nonlinear dam-linear rock foundation", "nonlinear dam-nonlinear rock foundation" and "linear dam-nonlinear rock foundation". The bilinear kinematic hardening model is employed to represent the nonlinearity of both dam body and rock foundation. The results obtained are compared to understand the effect of both material nonlinearities and interaction phenomenon on the dynamic behavior of the studied dam. In contrast to the nonlinearity of the rock foundation material, it is concluded that the nonlinearity of the concrete dam material has a significant impact on the behavior of the system. [ABSTRACT FROM AUTHOR]

Composite plate shear walls/concrete-filled (C-PSW/CFs), also known as SpeedCore systems, are a relatively new structural member in American codes and standards. Prior research has focused primarily on C-PSW/CF walls with either flange/closure plates or filled composite members as boundary elements. Walls without boundary elements have also been studied, but they are no longer permitted by the American Institute of Steel Construction (AISC 341-22). The reason is that composite walls without boundary elements do not provide adequate ductility for seismic design. This paper presents the results of experimental and numerical studies conducted to evaluate the cyclic lateral load behavior of C-PSW/CFs using hot-rolled structural steel members as boundary elements. The steel web plates of the C-PSW/CF specimens were connected to each other using threaded tie bars with double nut connections. Composite interaction between the steel and concrete infill was achieved using the tie bars and additional shear studs welded to the boundary elements. The composite walls were embedded and anchored to reinforced concrete foundation blocks using welded deformed bar anchors. The experimental investigations focused on the cyclic lateral load-drift responses including test observations and limit states, moment-rotation response of the plastic hinge and the section moment-curvature relationship, overall lateral stiffness, strength, and displacement ductility. The experimental results show that the specimens exceeded their nominal flexural capacities calculated using the plastic stress distribution method or fiber-based section modeling using measured material properties. The specimens had plastic hinge rotation capacity greater than 0.028 rad. and displacement ductility ratio greater than 5.2. Detailed 3D nonlinear inelastic finite element models and simpler fiber-based macro models of the tested specimens were developed and benchmarked using experimental results. The detailed 3D finite element models can reasonably simulate the global and local behavior of the specimens, and are recommended for conducting further parametric studies of composite wall design details. Simpler fiber-based macro models can efficiently simulate the cyclic lateral load behavior of the specimens, and are recommended for modeling C-PSW/CFs while simulating the behavior of multi-story building structures. [ABSTRACT FROM AUTHOR]

This paper describes the state of the art of structural steel reuse in Japan. A significant part of the material is taken from a document titled the Architectural Institute of Japan (AIJ) Recommendations for Sustainable Steel Building Construction (Draft) available only in the Japanese language. The motivations for and potential benefits of steel reuse are examined. The affinity between seismic design requirements and steel reuse is highlighted through a concept known as "damage-control" design. Some technologies for disassembly are introduced. The historical development and changes in Japanese structural steel are summarized, followed by a discussion on reusability of historical steel reclaimed from existing buildings. Reuse projects whose details are known to the authors are listed. The heart of the paper is a design procedure that specifies the structural engineer's role and involvement in planning, material procurement, and executing a steel reuse project. The discussion is concluded by six directions that should be pursued to make steel reuse a widely accepted reality in Japan. Among those directions are research needs to establish a procedure to quantify the remaining structural performance of reclaimed steel considering possible exposure to earthquakes, establish connections that allow for easy disassembly, and introduce modularized structural systems. High seismicity and the general practice to adopt full moment frames pose unique challenges for steel reuse in Japan. [ABSTRACT FROM AUTHOR]

An active type of upgraded tuned liquid column damper (AUTLCD) based on hedge-algebras (HA) theory is proposed to mitigate structural vibrations of seismic-excited buildings in this paper. The AUTLCD consists of an upgraded tuned liquid column damper (UTLCD) and an actuator to generate the control force, in which UTLCD is constituted by a traditional tuned liquid column damper (TLCD) fixed on an undamped tuned mass damper (TMD). In this study, the HA-based-on controllers are used to determine the value of control force through the state variables, including the displacement and velocity of the floor installing the actuator. This approach allows one to find the optimal parameters of UTLCD and the HA-based controller. The balancing composite motion optimization (BCMO), a novel and potential algorithm, is utilized for optimization problems in the paper. The effectiveness of AUTLCD is compared with an active tuned liquid column damper (ATLCD) having the same weight as the AUTLCD. The results obtained from this research indicate that AUTLCD is more effective than ATLCD for aspects of control performance and average control force. Furthermore, although the optimal HA controller is only designed for the El Centro earthquake data in 1940, it still offers a high-efficiency level for many other earthquakes. In addition, the HA-based controller also makes sure the system's stability in the operating process. [ABSTRACT FROM AUTHOR]

The noise attenuation of seismic data is an indispensable part of seismic data processing, directly impacting the following inversion and imaging. This paper focuses on two bottlenecks in the AI-based denoising method of seismic data: the destruction of structural information of seismic data and the inferior generalizability. We propose a flexible attention-CNN (FACNN) and realized the denoising work of seismic data. This paper's main work and advantages were concentrated on the following three aspects: (i) We propose attention gates (AGs), which progressively suppressed features in irrelevant background parts and improved the denoising performance. (ii) We added a noise level map M as an additional channel, making a single CNN model expected to inherit the flexibility of handling noise models with different parameters, even spatially variant noises. (iii) We propose a mixed loss function based on MS_SSIM to improve the performance of FACNN further. Adding the noise level map can improve the network's generalization ability, and adding the attention structure with the mixed loss function can better protect the structural information of the seismic data. The numerical tests showed that our method has better generalization and can better protect the details of seismic events. [ABSTRACT FROM AUTHOR]

With the continuous increase in building types, people's demand for buildings is increasing. In addition to focusing on the work of the building itself, high requirements are also placed on the safety, stability, and durability of the building. Especially in other earthquake-prone areas, it is even more necessary to strengthen seismic isolation research to reduce vibration. Rapid construction of environmental protection walls pays attention to environmental protection and efficiency during construction, which can effectively solve problems in the construction process, but the seismic resistance of rapid construction environmental protection walls is unknown. Therefore, this paper used artificial intelligence technology to study the seismic performance of rapid construction environmental protection walls and analyzed its vibration control. This paper firstly established the seismic performance analysis model of the environmental protection wall, used the finite element method to construct the environmental protection wall model, and then used the artificial intelligence algorithm to analyze the seismic performance of the rapid construction environmental protection wall. The experimental results showed that the peak load of the rapid construction environmental protection wall was about 250 KN, and the seismic performance was good. [ABSTRACT FROM AUTHOR]

This paper proposes a semi-automatic method of geographic information linking based on spatial relationships, entity names, entity categories and other features, combined with semantic and machine learning methods. First, we extracted geographic information from three geographic information sources: Open Street Map, Wikimapia, and Google places. The extracted geographic information is mainly for urban buildings in different regions. Secondly, we analyzed and extracted the characteristics of geographic information data to construct a geographic information ontology, and realized the integration of geographic data through the mapping of geographic information source data and geographic information ontology. Finally, the linking method of fusion classification algorithm support vector machine and K-nearest neighbor method are discussed separately. At the same time, it is compared with the linking method proposed by Samal et al. to comprehensively verify the accuracy of the method proposed in this paper from multiple angles, laying a good foundation for seismic information integration. [ABSTRACT FROM AUTHOR]

In order to solve the problems of complex construction process and long construction period in traditional embedded steel column base, this paper proposes a fully- assembled embedded steel column base joint. Two different constructions forms of specimens, high-strength bolt connection and anchor bolt connection, were designed and subjected to horizontal low cycle reciprocating loading tests to study the impact of different connection structures on their seismic performance.The numerical simulations of the tset was also carried out by using the software ABAQUS. The result shows that both connection structures of the specimens have safe and reliable connection capabilities and good seismic performance. The hysteresis curves and skeleton curves of the two connection forms basically overlap. Under large interlayer displace angles, the use of high-strength bolt connection joint has effectively delayed the stiffness degradation of the column base joint；Compared to the anchor bolt connection, its maximum ultimate bearing capacity has increased by 6.55%. At the same time, high-strength bolt connections can avoid the welding of the anchor bolt gaskets and the flange plate, to achieve green construction. In addition, the anchoring performance of anchor bolt connection is superior to high-strength bolt connection, which is suitable for cases where a small amount of welding is permitted on site. Therefore, two types of joints can be flexibly selected according to the engineering requirements in the actual design. • This paper innovatively proposes a fully-assembled embedded steel column base joint, which can achieve efficient assembly. • This study proposes two different constructive forms for this joints, both of which have good seismic performance. • Using high-strength bolts for connection has better ductility and allows for green construction. • The anchoring performance of anchor bolt connection is superior to high-strength bolt connection. [ABSTRACT FROM AUTHOR]