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This paper proposes a novel intensity measure (IM) based on the geometric mean of acceleration response spectral ordinates to assess the probabilistic performance of structures subjected to seismic loading. Instead of relying solely on the fundamental period, the proposed IM is evaluated across a fixed period range for all structural systems, which allows consideration of higher mode effects and period changes due to nonlinearity. The proposed seismic IM is evaluated using two established indices sufficiency and efficiency. Sufficiency quantifies the independence of an engineering demand parameter at a specific intensity level with ground motion characteristics such as seismic magnitude (M) and distance from site to fault plane (R). It is calculated by linear regression analysis, or using gradient-based relative sufficiency measures. On the other hand, efficiency is measured as dispersion across ground motions at a given intensity level for any physical response quantity. It helps to reduce computational demand for failure probability assessment by considering a smaller number of records compared to an inefficient IM for similar confidence levels. The effectiveness of the proposed IM along with 10 other IMs is demonstrated on single degree of freedom systems with various fundamental periods by performing nonlinear time history analysis using a far-field ground motion record set. The study is also extended to five degree of freedom lumped mass stick models, 2D models (4-, 8-, and 12-story archetype steel frames), and 3D reinforced concrete shear wall building model. The results indicate that the proposed IM limits dispersion to within 10% for long-time period structures, and demonstrates improved sufficiency across different structural systems. For example, gradient of the proposed IM with respect to magnitude M and site-to-source distance R for a 12-story steel frame is reduced by 42.9% and 94%, respectively, compared to spectral acceleration at fundamental time period. Potential application of this research lies in efficiently conducting seismic reliability assessment and design for structural systems. [ABSTRACT FROM AUTHOR]

The safety, stability, and long-term performance of reinforced concrete (RC) structures depend significantly on soil-structure interaction (SSI), a critical phenomenon governing the dynamic relationship between soil and structural behaviour. SSI plays a pivotal role in seismic design, influencing the stiffness, damping, and natural frequency of structures, yet its application in practical design remains underutilized due to challenges in modelling and integrating code provisions. This review synthesizes existing knowledge on SSI, emphasizing its impact on buildings, bridges, and foundations under static and dynamic loads. It highlights advancements in analytical, numerical, and experimental modelling methods, such as finite element analysis and discrete element methods, and evaluates their effectiveness in capturing the complex interactions between soil and structural systems. The review identifies key gaps, including a lack of unified guidelines in international codes, inadequate integration of SSI in real-world design processes, and limited exploration of its role in emerging engineering challenges like sustainability and climate resilience. Historical seismic events, such as the Kobe and Loma Prieta earthquakes, are analysed to underscore the detrimental consequences of neglecting SSI considerations. Additionally, the review discusses recent innovations, including the application of machine learning and advanced computational tools, and their potential to enhance the accuracy and efficiency of SSI analysis. This study offers actionable insights for improving design practices, such as adapting SSI frameworks for structures on soft soils and incorporating dynamic interactions in seismic design codes. It concludes with a call for interdisciplinary collaboration and future research into novel SSI applications, including its integration with smart sensing technologies and sustainable infrastructure design. This review bridges the gap between theoretical advancements and practical applications of soil-structure interaction (SSI) by synthesizing current knowledge, identifying critical research gaps, and proposing innovative solutions to enhance structural resilience, sustainability, and seismic safety. Highlights: ➢ The introduction of SSI and the previous studies in seismic design is debated. ➢ Need, significance and the standard code provisions of SSI of different countries are explained. ➢ Solving methods of SSI are discussed. [ABSTRACT FROM AUTHOR]

Well foundations are one of the most widely used deep foundations for bridges. As in case of other foundations, these foundations are also subjected to combined vertical force V, horizontal force H, and moment, M. In this research study, the geotechnical capacity of well foundation in frictional soil is determined under gravity and seismic loading condition, using 3D finite element limit analyses (FELA). Applicability of modelling of the well foundation as a rigid body, and effect of shape of bottom plug of the well, on the foundation capacity is also studied. Failure patterns at salient points along the capacity surface are identified and their characteristics are explained. Specifically, the location and shift in the position of point of rotation, for different combinations of H-M loading, are discussed in detail. A parametric study is also performed to identify the effect of vertical load, embedment depth ratio of foundation, soil strength parameters and seismic loading on foundation capacity. The capacity of the well foundation obtained using design methodology of Indian bridge design standards is also compared with the numerical results and a modification is proposed in the existing design methodology. The proposed methodology enables the designer to determine reasonably good estimate of the foundation V-H-M capacity. [ABSTRACT FROM AUTHOR]

The seismic damage of underground structures has been extensively investigated, and it has been demonstrated that underground structures located at weak interlayer sites are more prone to damage. In this study, a two-story two-span rectangular frame subway station structure is analyzed. A two-dimensional soil-underground structure model is developed using the large-scale finite element analysis software ABAQUS. The equivalent linear soil-underground structure dynamic time-history analysis method is employed to examine the seismic response of underground structures at weak interlayer sites. Variations in the thickness and shear wave velocity of the weak interlayer soil are analyzed. The seismic mitigation effects of split columns and prototype columns in underground structures at weak interlayer sites are systematically compared. The findings indicate that the relative displacement and internal force of key structural components significantly increase when the weak interlayer intersects the underground structure. Furthermore, as the thickness of the interlayer increases, the displacement and internal force also escalate. When the thickness of the weak interlayer remains constant and the shear wave velocity decreases, the relative displacement and internal force of the key structural components gradually intensify. Replacing ordinary columns with split columns substantially reduces the internal force of the middle column, providing an effective seismic mitigation measure for underground structures. [ABSTRACT FROM AUTHOR]

Nonlinear pushover analysis involves an extremely iterative process necessary for satisfying the design requirements of performance-based codes. This analysis also demands significant computational resources and advanced scientific efforts. In this study, we introduce a computer-based method for 2D-braced steel buildings that incorporates pushover analysis, optimization techniques, and optimality criteria methods to automatically design the pushover drift performance. An ant colony metaheuristic optimization algorithm is employed to achieve optimal performance-based designs for columns, chevron braces, and beams in steel moment frames. The initial phase includes implementing optimization codes in MATLAB and OpenSees for conducting the nonlinear static analysis of the 2D-braced steel frames. Several optimal configurations are produced for each brace and frame by addressing the nonlinear optimization problem. In the second step, a nonlinear pushover analysis is conducted in accordance with the provisions of the FEMA 356 code. This analysis takes into account constraints on relative displacement and plastic hinge rotation to ensure that the structure achieves the specified performance levels. Finally, the third step involves selecting the optimal design for each frame and subsequently plotting the pushover, drift and convergence curves for each frame and performance levels. This selection process ultimately aims to satisfy the criteria of performance-based design, including life safety, collapse prevention, and immediate occupancy, while minimizing the total weight for three 2D steel chevron frames: a 5-story, a 9-story, and a 13-story configuration. [ABSTRACT FROM AUTHOR]

The behaviour of horizontal floor diaphragms plays a crucial role in ensuring the overall response of a building during earthquakes, as the stiffness of these diaphragms determines whether the structure will act as an integrated system. If the diaphragms do not exhibit sufficient stiffness, differences in the redistribution of forces on wall elements arise, increasing the risk of significant deformations and even local damage, which is commonly observed in earthquake-affected areas. Additionally, flexible diaphragms heighten the risk of torsional effects. Due to these factors, more attention should be given to the response of buildings with flexible diaphragms. Eurocode standard specifies general requirements under which diaphragms should be considered rigid within their plane, depending on the maximum diaphragm moment. However, specific guidelines regarding the geometric and material properties of elements that significantly impact seismic behaviour are not included in the existing European standards. This served as a basis for conducting a numerical study analysing the in-plane behaviour of floor elements made from different materials. This study, limited to a simple box-shaped structure with masonry walls, symmetrical in both orthogonal directions, evaluated and thoroughly analysed the deformations for different types of diaphragms, including prefabricated wooden frame-panel floors, CLT panels, and reinforced concrete slabs. Special emphasis was placed on wooden structural elements due to the increased demand for timber construction, as the behaviour of these elements needs to be properly studied, especially in seismic regions. The study results were obtained through FEM analysis using the SCIA Engineer software, version 22. The modelling of elements was carried out considering the orthotropy of brick wall and wooden ceiling elements, as well as simulating the appropriate shear stiffness of the connecting means. [ABSTRACT FROM AUTHOR]

This paper presents the seismic design of a steel moment‐resisting knee‐braced frame (MKF) using the theory of plastic mechanism control (TPMC) within the capacity‐based design framework. The MKF is an alternative system to MRFs, wherein knee elements are utilized to provide rigid connections and enhance lateral stiffness. Capacity‐based design, the predominant approach in current seismic provisions, relies on two key principles: (1) selecting specific structural components as fuses with sufficient ductility to dissipate seismic energy, and (2) ensuring non‐fuse elements can resist the maximum probable reactions from these fuses. The ultimate goal is to achieve a global mechanism where yielding occurs in all structural fuses and at the base of first‐story columns. However, existing seismic design provisions often struggle to fully satisfy the second principle due to the lack of a method for controlling failure modes. TPMC addresses this challenge by ensuring compliance with the second principle, grounding its approach in the kinematic method and the mechanism equilibrium curve within the rigid‐plastic analysis framework. By considering all potential story‐based undesirable mechanisms and calculating the required plastic moment of columns up to a target design displacement, TPMC ensures adherence to the second principle of the capacity‐based design approach, leading to the achievement of a global collapse mechanism. In this paper, an iterative method is proposed for designing beams and knee elements by considering plastic hinges at both ends of the beams, followed by a TPMC‐based methodology for designing columns to ensure a global mechanism. A parametric analysis of a single‐story single‐span MKF explores the effects of knee element geometry (lb/L${l}_b/L$ and β$\beta $) on component demands. The results indicate that optimal parameter ranges of 0.175≤lb/L≤0.25$0.175 \le {l}_b/L \le 0.25$ and 40∘≤β≤60∘$40^\circ \le \beta \le 60^\circ $ can minimize the demands for MKF components. Practical design examples are illustrated using three steel MKFs, each consisting of four, seven, and ten stories with five spans. Pushover analysis and nonlinear dynamic analyses were performed to demonstrate the effectiveness of the proposed design procedure in ensuring the attainment of a global mechanism and excellent seismic performance under real ground motions. [ABSTRACT FROM AUTHOR]

Large databases of cyclic tests on flexure‐ or shear‐critical concrete members and shear‐critical connections of columns to beams or slabs are used to estimate the uncertainty inherent in experimental data in literature—as read by users. To this end, the predictions of two different, presumably independent, design‐oriented models for the properties of interest are used to establish the "central tendency" of data, against which individual tests or small groups thereof are assessed. Properties considered are: (a) the cyclic ultimate chord‐rotation of flexure‐controlled members with continuous or lap‐spliced deformed bars, (b) the cyclic shear strength of shear‐critical members, (c) the chord‐rotation at yielding of rectangular columns with plain bars, and (d) the cyclic shear strength of shear‐controlled beam‐column and slab‐column joints. Results suggest that the data from each test campaign have a certain degree of bias, specific to it. Test campaigns with ratio of estimated average deviation from the "central tendency" to the standard deviation of campaign deviations (called "data uncertainty") which is far into the tail of the Normal distribution may be excluded as questionable. This systematic bias, along with other types of "data uncertainty" addressed in this work, seem to contribute to the apparent scatter of model predictions with respect to cyclic test results the equivalent of a coefficient of variation of model‐to‐test‐ratio of at least 10% and possibly as high as 25%–30%. Model uncertainty seems to contribute to this scatter the equivalent of a coefficient of variation of at least 15% in shear‐controlled connections, or as much as 25% in the case of flexural deformation capacity of members with deformed bars; the cyclic shear resistance of members and—with the reservation of the small number of tests—the chord‐rotation at yielding of members with plain bars, are in‐between. [ABSTRACT FROM AUTHOR]

The primary objective of this study is to probe an optimum pattern of anchor distribution to improve seismic behavior of a series of anchored walls as a temporary excavation support system, without increasing the cost of their preliminary static design. To this end, the related literature including both nail and anchors as reinforcement was, firstly, thoroughly reviewed to shed light on the probable successful scenarios. It is concluded from the literature that the bottom rows of reinforcement play an important role in providing seismic stability, while the top rows reduce seismic displacement of the walls. Additionally, in the absence of liquefaction or cyclic softening of the soil, the seismic stability of nailed walls has been satisfactory in all previous seismic events due to their conservative design. Thus, control of seismic displacements is crucial. Furthermore, it has been pointed out by numerous studies that partly the interaction of the anchors and the wall with the soil and partly the amplification of the seismic waves through the wall require a numerical analysis to be simulated properly. Secondly, detailed calibration of a 3D numerical model was accomplished by simulating a previously conducted centrifuge modeling of a nailed wall as an excavation support system, experiencing cyclic loadings. Subsequently, different patterns of anchors with the same overall length were tried in the calibrated numerical models and their seismic performance were presented in terms of wall movement and settlement of the soil surface behind the wall. The primary finding of this study indicates that increasing the length of the anchors to 0.9 times the excavation height, while positioning them at a depth equal to one-fourth of the excavation depth, considerably reduces seismic wall displacement and settlement in sandy soils of the models studied herein. Moreover, though different models exhibited similar displacements under static conditions, their seismic displacements varied significantly. Notably, the above-mentioned configuration led to the least seismic displacement of the anchored wall investigated in this research. [ABSTRACT FROM AUTHOR]

Passive dampers play a key role in the smart and reliable design of building structures under uncertain earthquake loading. Passive dampers enable structural designers to enhance the potential of their structural design techniques and acquire the powerful methodologies for more reliable structures under unpredictable uncertainties. While there exist many review articles on optimization of passive dampers, this review is aimed at introducing a new perspective that most passive damper algorithms can be classified based on the combination of several component approaches with different objectives. Mixed approaches considering input uncertainties are particularly highlighted. Research focused on comparison among different optimization methods is also investigated. [ABSTRACT FROM AUTHOR]

Earthquake catastrophes continue to cause substantial damage and casualties in many parts of the world. Despite design codes and standards having succeeded in reducing life losses during earthquakes, the level of damage in buildings after severe earthquakes still cannot be precisely predicted. Code provisions focus on the safety of buildings with no consideration of the amount of damage expected after an event. Current U.S. guidelines designate three performance levels related to the inelastic rotational demands of RC shear walls––immediate occupancy, life safety, and collapse prevention. The damage corresponding to these performance levels is minor, moderate, and severe, respectively. In the current study, these performance limits were implemented, along with other recognized standards, in order to design four RC ductile shear wall buildings with different heights located in a high seismic hazard zone. Each building was designed based on Canadian building codes to reach the three designated performance levels. For each case, the quantities of the constitutive materials of the RC shear walls were estimated and compared. The impact of the targeted performance level on the building's gravity-load-resisting system was also investigated. The cost effectiveness of using moderately ductile shear walls in high seismic hazard zones was also examined. [ABSTRACT FROM AUTHOR]

This paper presents a procedure for simplified collapse probability prediction of RC frame buildings when subjected to ground motion intensities commonly used in designing buildings. For this purpose, seismic collapse probability of a range of RC moment resisting frame buildings are assessed at the design basis earthquake (DBE) and the maximum considered earthquake (MCE) levels of seismic intensity by conducting more than a thousand nonlinear response history analyses (NRHA) using a suite of 40 seismic ground motion records. The 13 buildings included in the investigation have different heights (5–15 storeys) and footprints (3–6 bays), are designed to different target maximum inter‐storey drifts (within the code specified limit), and have critical members detailed to sustain different levels of confinement and anti‐buckling demands. The NRHA results consistently demonstrate that the design inter‐storey drift and the anti‐buckling detailing of longitudinal rebars in the critical frame members strongly influence the collapse probability of RC frame buildings. The results also show that while RC frame buildings designed to reach 2.5% (or less) inter‐storey drifts and detailed for ductile seismic performance can successfully avoid collapse at DBE, avoidance of collapse at DBE cannot be guaranteed if RC frames are designed to reach a target drift of more than 2% and not detailed for full ductility. At MCE, collapse probability is found to consistently exceed 10% unless the building is designed to incur no more than 1% plastic drift and the frame members have ductile detailing. Based on the NRHA results of the 13 case study buildings, easy‐to‐use equations relating their seismic collapse probability at MCE with the design drift and a quantifiable measure of ductile detailing are generated and validated by comparing with the collapse probability obtained by NRHA of an independent RC frame building. The proposed equations provide a rapid, yet reasonably reliable tool for performance‐based seismic design of RC frame buildings, and enable designers to estimate seismic collapse probability of RC frame buildings without having to conduct cumbersome NRHA. [ABSTRACT FROM AUTHOR]

This work explores earthquake-induced kinematic bending in the so far unresolved case of a pile embedded in a two-layer soil with a thin surface layer. The problem is treated analytically by means of a generalised Winkler model, which in addition considers the effect of boundary conditions at the pile head over earlier contributions on the subject. Novel analytical closed-form expressions of the kinematic bending moment at the pile head and at the interface between the two soil layers are provided for both fixed- and free-head piles. The analytical solutions are validated through a rigorous finite-element model, which proves a remarkable accuracy in the static regime. While for interface bending the past literature indications for the dynamic coefficient make the proposed formula accurate for both shallow and deep interface, a novel dynamic interaction factor, describing dynamic effects for pile-head bending, is introduced. A numerical example provides guidance on application of the formulae in real design scenarios. [ABSTRACT FROM AUTHOR]

In this study, the effects of the spectral acceleration at the superstructure first‐mode period on the isolator displacement are investigated for far‐field ground motions. For this purpose, two different base‐isolated models are subjected to 165 far‐field ground motions. It is demonstrated that considering the spectral acceleration at the superstructure first‐mode period, besides that at the effective period, improves the estimation accuracy of isolator displacement. ASCE 7‐22 modifies the scaling period range to consider the superstructure first mode period and proposes the new period range from the superstructure first‐mode period to the 1.25 times effective period. In the ASCE 7‐22, the same weight factor is used for the whole period range. However, the present study shows that adding the superstructure first‐mode related period range with appropriate weight factor to the effective period‐based scaling range decreases the dispersion of isolator displacement in the nonlinear response history analyses (NRH). Then, to overcome the spectral shape effects on the fragility curves, a vector‐valued intensity measure parameter is obtained by combining spectral acceleration at the effective period and reduced spectral acceleration at the superstructure first‐mode period. The optimum contribution factor for the spectral acceleration at the superstructure first‐mode period is defined as the ratio of the superstructure first‐mode period to the effective period. The article shows that the proposed parameter is efficient and sufficient to be used as an intensity measure for far‐field ground motions. Furthermore, regression analysis results indicate that this vector‐valued intensity measure parameter correlates well with the isolator displacement. Further, the article shows that using the proposed IM parameter in the fragility curves makes the collapse margin ratio of these curves less sensitive to the spectral shape of the selected ground motions. [ABSTRACT FROM AUTHOR]

To reasonably evaluate the damage degree of a single-layer spherical mesh shell structure during an earthquake, we develop an improved two-parameter nonlinear combined damage model based on the existing Park-Ang damage model for mesh-shell structures by subtracting the displacement of the elastic phase from the displacement term and adopting the form of a nonlinear combination of the displacement term and the energy dissipation term. Based on material damage accumulation, 144 sets of numerical models covering different spans, rise/span ratios, roof masses, and member sizes were developed and fitted to obtain the values of the parameters to be determined in the damage model, and then, an improved Park-Ang two-parameter damage model for mesh-shell structures was proposed. The critical values of damage indices of the structure at the four performance points were 0, 0.3, 0.7, and 1. The validity of the two-parameter damage model was verified using a single-layer spherically mesh shell structure with three different structural parameters. The results revealed that the improved Park-Ang two-parameter damage model has a damage value of zero in the elastic phase, which satisfies the lower bound convergence and has a good computational accuracy and small dispersion. In addition, the index values of the four performance points reflect the performance status of the mesh-shell structure, indicating that the improved Park-Ang damage model is suitable for evaluating the damage evolution process of the structure under seismic action. This proposed damage model lays a foundation for vulnerability analysis and seismic risk assessment of mesh shell structures, a basis for post-earthquake repair, the development of an optimal design for mesh shell structures, and the analysis of casualty and economic loss statistics. [ABSTRACT FROM AUTHOR]

Coseismic surface displacement can cause major damage to buildings located on faults. Therefore, it is important to quantitatively evaluate the future surface displacement of active faults. The commonly used deterministic evaluation methods often tend to overestimate surface displacement values, so researchers are working toward probabilistic fault displacement hazard analysis (PFDHA). However, the PFDHA assumes that earthquakes occur equally in time, which is not consistent with the physical mechanism of earthquake occurrence. Elastic rebound theory and paleoseismic research results show that the accumulation and release of energy in the crustal medium have cyclical characteristics. In this study, using two parameters, the strong earthquake recurrence period (TRP) and strong earthquake elapsed time (tet), of active faults, the displacements of active faults with different TRP and tet under different exceedance probabilities are obtained. The calculation results indicate that the surface displacement hazard of the weakly active and extremely weakly active faults in the Holocene does not need to be considered; for the moderately and strongly active faults in the Holocene, the surface displacement result is lower than that provided by the deterministic method. According to the importance of the project, the calculation results of the PFDHA-td method under different exceedance probabilities are selected. [ABSTRACT FROM AUTHOR]

The slope of a linear approximation of a probabilistic seismic hazard curve, when it is represented in the log‐log scale, is a key parameter for seismic risk assessment based on closed‐form solutions, and other applications. On the other hand, it is observed that different hazard models can provide, at the same site, comparable ground shaking, yet appreciably different slopes for the same exceedance return period. Moreover, the slope at a given return period can increase or decrease from low‐ to high‐hazardous sites, depending on the models the probabilistic seismic hazard analysis (PSHA) is based on. In the study, the sensitivity of the slope to the main model components involved in PSHA was explored, that is: the earthquake rate, the magnitude and source‐to‐site distance distributions, and the value of the residual of ground motion models (GMM). With reference to a generic site, affected by an ideal seismic source zone, where magnitude follows the Gutenberg‐Richter (G‐R) relationship, it was found that the local slope of hazard curve increases with the following factors in descending order of importance: (i) increasing distance from the source; (ii) decreasing maximum magnitude and increasing b$b$‐value of the G‐R model; (iii) increasing rate of earthquakes of interest; (iv) increasing residual of the GMM. These results help explain the systematic differences in hazard curve slopes found in three authoritative hazard models for Italy, and the related impact on simplified risk assessment. [ABSTRACT FROM AUTHOR]

Abstract The safety, stability, and long-term performance of reinforced concrete (RC) structures depend significantly on soil-structure interaction (SSI), a critical phenomenon governing the dynamic relationship between soil and structural behaviour. SSI plays a pivotal role in seismic design, influencing the stiffness, damping, and natural frequency of structures, yet its application in practical design remains underutilized due to challenges in modelling and integrating code provisions. This review synthesizes existing knowledge on SSI, emphasizing its impact on buildings, bridges, and foundations under static and dynamic loads. It highlights advancements in analytical, numerical, and experimental modelling methods, such as finite element analysis and discrete element methods, and evaluates their effectiveness in capturing the complex interactions between soil and structural systems. The review identifies key gaps, including a lack of unified guidelines in international codes, inadequate integration of SSI in real-world design processes, and limited exploration of its role in emerging engineering challenges like sustainability and climate resilience. Historical seismic events, such as the Kobe and Loma Prieta earthquakes, are analysed to underscore the detrimental consequences of neglecting SSI considerations. Additionally, the review discusses recent innovations, including the application of machine learning and advanced computational tools, and their potential to enhance the accuracy and efficiency of SSI analysis. This study offers actionable insights for improving design practices, such as adapting SSI frameworks for structures on soft soils and incorporating dynamic interactions in seismic design codes. It concludes with a call for interdisciplinary collaboration and future research into novel SSI applications, including its integration with smart sensing technologies and sustainable infrastructure design. This review bridges the gap between theoretical advancements and practical applications of soil-structure interaction (SSI) by synthesizing current knowledge, identifying critical research gaps, and proposing innovative solutions to enhance structural resilience, sustainability, and seismic safety. Graphical Abstract

This paper reviews the applications of the multi degree-of-freedom (MDOF) equivalent linear system in seismic analysis and design of planar steel and reinforced concrete framed structures. An equivalent MDOF linear structure, analogous to the original MDOF nonlinear structure, is constructed, which has the same mass and elastic stiffness as the original structure and modal damping ratios that account for the effects of geometrical and material nonlinearities. The equivalence implies a balance between the viscous damping work of the equivalent linear structure and that of the nonlinearities in the original nonlinear structure. This work balance is established with the aid of a transfer function in the frequency domain. Thus, equivalent modal damping ratios can be explicitly determined in terms of the period and deformation levels of the structure as well as the soil types. Use of these equivalent modal damping ratios can help address a variety of seismic analysis and design problems associated with planar steel and reinforced concrete framed structures in a rational and accurate manner. These include force - based seismic design with the aid of acceleration response spectra characterized by high amounts of damping, improved direct displacement-based seismic design and the development of advanced seismic intensity measures. The equivalent modal damping ratios are also utilized in the context of linear modal analysis for the definition and construction of the MDOF response spectrum. Furthermore, the equivalent modal damping ratios are employed in a seismic retrofit method for steel-framed structures with viscous dampers. Finally, it is demonstrated that modal behavior (or strength reduction) factors can be easily constructed based on these modal damping ratios for a more rational and accurate force-based seismic design, including the determination of inelastic displacement profiles.

To improve the seismic performance of precast concrete reinforced frame structures which are widely used worldwide, and enable a certain repairable function for the precast structure after an earthquake, this paper proposes a new type of precast concrete frame joint using a full grouting sleeve connection with a disc spring device. The disc spring device was connected in series to the longitudinal reinforcement located in the plastic hinge zone at the beam end to provide a restoring force and protect the concrete. Six exterior beam-column joints consisting of one cast-in-situ beam-column joint and five precast concrete frame joints, using a fully grouted sleeve connection equipped with or without a disc spring device, were designed and fabricated. The failure process, hysteretic characteristics, and energy dissipation capacity of the joint specimens were analyzed based on reversed cyclic loading test. The results showed that the energy dissipation and seismic performance of the newly precast concrete joints equipped with the disc spring device were better than those of the precast concrete frame joints connected by ordinary grouting sleeves without a disc spring device. The disc spring device proposed in this study plays a similar role as a damper in the precast joint during loading and has the characteristics of concentrated damage as it transfers part of the damage in the joint core area to the built-in disc spring area at the beam end. Additionally, the deformation of the precast joints under a lateral seismic load was theoretically calculated, the calculated results were in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

This research aims to apply the displacement-based design method (DBDM) for the seismic design of reinforced concrete-coupled shear wall buildings equipped with energy dissipation dampers. The DBDM offers design simplicity by focusing on structural design based on a target design displacement, where the building converts into a single degree of freedom (SDOF) system. The implementation of dampers aims to reduce repair costs and downtime for buildings following significant seismic events. Two types of dampers are utilized in this study: metallic damper and viscoelastic damper. The DBDM procedure begins with determining the target displacement, which corresponds to the specific story drift ratio of the structural system, using a nonlinear static pushover analysis. For the structural wall system considered in this study, a target drift ratio of 1/250 is selected due to the inherent rigidity of the structure. The effective damping factor is then determined from the average energy absorption, which is based on the ductility factor of each structural member. Additionally, the effective period of the building is obtained from the displacement spectrum of the design-level earthquakes. Finally, the required damper shear capacity for the SDOF system is calculated based on the target deformation and effective stiffness. The design earthquakes are generated from the acceleration response spectrum for Level 2 earthquakes, as specified in the Japanese seismic code, utilizing three different sets of phase information: Kobe, El Centro, and random phase records. The effectiveness of the DBDM is scrutinized through a comparison with results obtained from time history analysis. The results obtained for 6-, 12-, and 18-story RC-coupled shear walls with energy dissipation dampers indicate that the proposed design methodology effectively meets the specified design objectives. [ABSTRACT FROM AUTHOR]

Beam–column joints are critical in reinforced concrete moment-resisting frames. Adequately designed beam–column joints support the plastic hinging of the adjoining beams under seismic actions and transfer gravity loads, both of which are critical for the energy dissipation and survival of buildings during earthquakes. Beam–column joints in exterior frames of buildings are occasionally eccentric such that the axes of the beam and column are offset from one another. Previous work on eccentric joints indicates an inferior seismic behavior compared to concentric joints. Beams flush with the concrete column represent the maximum eccentricity considered in previous studies. However, beam–column joints with higher eccentricity where the beam section only partially intersects with the column exist in some buildings. The impact of this notably high beam eccentricity on the seismic performance of joints has not been documented in studies published in open literature to the knowledge of the authors. This paper presents an experimental study focused on a joint geometry characterized by a beam eccentricity exceeding half the column width. The objective is to lay the groundwork for understanding how such eccentricity affects the seismic performance of reinforced concrete beam–column joints. The experiments involved reversed cyclic testing of four large-scale beam–column cruciform assemblages. The results indicate that the joints had sufficient core capacity to develop plastic hinges in the beams. In addition, the tested assemblies exhibited highly ductile behavior and considerable postpeak energy dissipation. The inadequacies of the design documents on such joints are discussed in detail. Based on the findings, a suggestion was made to evaluate the shear strength of such joints. Finally, a strengthening scheme using fiber-reinforced polymer patching was evaluated to improve the seismic performance with minimal work on the joint. The strengthened joint showed similar behavior with a higher energy dissipation compared to the unstrengthened joints. [ABSTRACT FROM AUTHOR]

This study seeks to integrate steel shear walls with precast concrete systems into stable and resistant structures against lateral loads. It is desired to study the ductility factor, lateral strength, and behavior as well as the energy absorption of this integrated system compared to the precast concrete frame without a shear wall. For this purpose, two steel shear wall samples made of mild steel and galvanized steel plates are constructed within a precast concrete frame. The assembly is tested under a cyclic lateral load. The integrity of the connections of steel strips of the wall together, and the boundary of the wall to the frame, is observed to be excellent. The main failure mode is composed of the diagonal yielding of the steel wall. The system benefits from large hysteresis loops and no degradation because of any instability. The beam‐column connections remain almost intact even at large cycles of deformation. Moreover, a bare precast concrete frame is tested in the same way to compare the lateral behavior. The utilized ductile beam‐column connections are successful in retaining the integrity of the system until large drifts. However, the seismic design characteristics of the bare frame turn out to be inferior to the steel shear wall system. Results of the cyclic tests show that by proper design of the interior and exterior connections of the shear wall as well as the beam‐column connections, the steel shear wall system can largely increase the stiffness, ultimate strength, and energy dissipation capacity of a bare precast moment resisting reinforced concrete frame. On top of that, the system is able to retain its integrity up to lateral drifts over 2%. [ABSTRACT FROM AUTHOR]

The seismic design of building diaphragms is one of the most vexing tasks today. Diaphragms are the structural elements primarily designed to transfer in-plane forces to the lateral force-resisting system. Design challenges increase when modeling diaphragms in nonlinear response-history analyses. The main complexity lies in choosing a computationally efficient model and establishing the demands and force distribution throughout the diaphragm. This paper describes two commonly used methods and compares the results in the design forces. A reinforced concrete core-wall building with a flat-slab transfer diaphragm is presented as a case study. Diaphragms were modeled with linear shell elements and the stringer-panel model. Differences in the magnitude of the forces are not significant, although visible differences are observed in the presentation of the results. The stringer-panel model shows a clear and unambiguous load path for the in-plane forces, making it an attractive alternative for the analysis of diaphragms. [ABSTRACT FROM AUTHOR]

The seismic design of structures is an emerging practice in earthquake-resistant construction. Therefore, using energy-dissipation devices and optimizing these devices for various purposes are important. Evolutionary computation, nature-inspired, and meta-heuristic algorithms have been studied more in recent years for the optimization of these devices. In this study, the development of evolutionary algorithms for seismic design in the context of multi-objective optimization is examined through bibliometric analysis. In particular, evolutionary algorithms such as genetic algorithms and particle swarm optimization are used to optimize the performance of structures to meet seismic loads. While genetic algorithms are used to improve both the cost and seismic performance of the structure, particle swarm optimization is used to optimize the vibration and displacement performance of structures. In this study, a bibliometric analysis of 661 publications is performed on the Web of Science and Scopus databases and on how the research in this field has developed since 1986. The R-studio program with the biblioshiny package is used for the analyses. The increase in studies on the optimization of energy dissipation devices in recent years reveals the effectiveness of evolutionary algorithms in this field. [ABSTRACT FROM AUTHOR]

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