Search

Local site conditions may pose a significant influence on the seismic responses of submarine pipelines by altering both the offshore motion propagation and soil‐structure interaction (SSI). This paper aims to provide an in‐depth understanding of the influence regularity of local site conditions on the seismic performance of free‐spanning submarine pipelines (FSSPs). For this purpose, a suite of underwater shaking table tests were performed to investigate the seismic responses of FSSP subjected to the offshore spatial motions at three site categories. Response comparison factor (χR.ij${\chi }_{R.ij}$) is defined to quantify the structural response discrepancies caused by the seismic inputs at different sites. The test results indicate that responses of the studied model FSSP gradually increase as spatial offshore motions at softer soil sites are employed as inputs; and the values of χR.ij${\chi }_{R.ij}$ vary with a maximum magnitude of up to 40%–60% for different response indices when the site soil changes from fine sand to clay. Subsequently, the corresponding numerical simulations are carried out to reproduce the seismic responses of the test model. The experimental and numerical results meet a good agreement, indicating that the developed numerical modeling method can accurately predict the seismic responses of FSSPs. Following this verified modeling method and using the p‐y approach to address the SSI effect, fragility surfaces of the studied FSSP are derived in terms of PGA and site parameter VS30${V}_{S30}$ (shear‐wave velocity in the top 30 m of the soil profile) via probabilistic seismic demand analyses. The impact of local site conditions on the seismic performance of the FSSP is quantitatively examined by comparing the fragility curves corresponding to various VS30${V}_{S30}$. Furthermore, a fast seismic damage assessment method is proposed for efficiently evaluating the performance of FSSPs buried in various offshore soil conditions. This approach proves beneficial for designers and decision‐makers, enabling accurate estimation of seismic damage and facilitating the implementation of post‐earthquake maintenance measures for FSSPs. [ABSTRACT FROM AUTHOR]

This study aims to reveal the control mechanism of viscoelastic (VE) energy dissipation braces with strong mechanical nonlinear characteristics on the seismic response of reinforced concrete (RC) frame structures. Firstly, a new STM32-Matlab-OpenSees joint hybrid test platform is developed by introducing OpenSees, which is convenient for structural modeling and fast for structural calculation. The overall architecture and operation of the hybrid test platform are comprehensively analyzed. Then, a series of simulated seismic hybrid tests on three-dimensional (3D) RC frame structures with VE energy dissipation braces under different seismic waves are successfully carried out. Lastly, the hybrid test results of this structure system at different working conditions are compared and analyzed comprehensively. The research results show that the developed platform breaks the boundary limitation that OpenSees relies on the framework software OpenFresco and can only be connected to specific control systems in the hybrid test. Thus, it greatly expands the application scope of flexible configuration controller and actuator categories for the hybrid test platform, and it also provides a good reference value for the establishment and implementation of similar hybrid test platforms. Under the action of various seismic waves, VE energy dissipation braces has good universality for the shock absorption of RC frame structures. The damping control effect and energy dissipation efficiency of VE energy dissipation braces are significantly different under various seismic waves. In the design of RC frame structures with VE energy dispersion braces, it is very necessary to conduct the seismic analysis of the structures under multiple ground motions with wide frequency domain. The additional position of VE energy dissipation braces should be an important analysis indicators in the optimization design of the structures. [ABSTRACT FROM AUTHOR]

To predict the seismic response of column‐supported silos (CSSs), the granular–structure interaction (GSI) analysis method is proposed with considering the combined effect of the friction between the particles–particles and the particles–silo wall. Using free‐body dynamic equilibrium equations, we reconstruct the mutual interactions between different grain portions and between the grains and the silo wall to develop the ideal calculation model of the CSS structure. Based on the analysis model, additional dynamic overpressure and the effective mass caused by the stored content interacting with the silo wall is obtained with different slenderness ratios and peak accelerations. The additional bending moment caused by the friction between the particles and silo wall is further quantified. To verify the reliability of the proposed method, we discuss some applicative examples by comparing the GSI method with other theories, Eurocode 8, and experimental results. Moreover, the along‐the‐height acceleration profiles of the silo wall and the ensiled content are analyzed according to the shaking‐table tests. The results show that the GSI method can match Janssen's theory well in the case of static pressure at slenderness ratios exceeding 1.0. The overpressure profiles along the height of the silo wall follow a nonlinear distribution, different from Eurocode 8. The bending moment obtained by predictive formulas agrees well with the experimental results for the CSS, indicating that the GSI method is reasonable. Some design and construction recommendations, including the maximum overpressure position, the reference range of the dynamic overpressure coefficient, and the reduction factors of the ensiled content mass, are proposed to facilitate the engineering applications of CSSs, considering different slenderness ratios. [ABSTRACT FROM AUTHOR]

This article takes STC long and short columns as the research objects, and first conducts quasi-static tests to preliminarily explore the failure characteristics of STC long and short columns under horizontal reciprocating loads. Then, a large number of numerical analysis models are established to explore the influence of coaxial compression ratio, steel pipe wall thickness, wood cross-sectional area, and bending point height on the seismic performance of STC long and short columns through numerical analysis. The results indicate that although the trend of changes in STC long columns and short columns under these factors is the same, STC long columns mainly resist bending and compression, while STC short columns mainly bear shear and bending resistance. Finally, the calculation formulas for the compressive bending bearing capacity of STC long columns and the shear bending bearing capacity of STC short columns were derived through theoretical analysis. The accuracy and safety of the formulas were verified through a large number of numerical simulation results. [ABSTRACT FROM AUTHOR]

This paper presents results on what the conditions of testing for assessing the adequacy of seismic isolators in the maximum considered earthquake should be by utilizing an approach in which the cumulative dissipated energy history is used as the performance parameter. This test is what is described as Item 4 in section 17.8.2.2 of standard ASCE/SEI 7. The approach used follows the paradigm of another study in which the history of temperature at the sliding interfaces or in the bulk of the lead core of isolators was used. In conducting this work, many isolation systems (a total of 96 systems, single friction pendulum, triple friction pendulum, and lead‐rubber) were used, with isolator models capable of simulating the effects of heating on the strength of the isolators. The study utilized a large set of bi‐directional ground motions with short‐ and long‐duration characteristics (71 pairs of short‐ and long‐duration ground motions, 96 isolation systems, three seismic intensities, for a total of 40,896 ground motion pairs). The adequacy tests were designed to reproduce various percentile cumulative energy histories obtained in the response history analysis. The requirements of these tests are compared to the testing requirements obtained by the use of temperature history as the performance criterion, and the test currently prescribed as test item 4 of section 17.8.2.2 of standard ASCE/SEI‐7. The study shows that use of the cumulative dissipated energy as the performance criterion for designing tests to represent the effects of maximum earthquake results in onerous testing requirements. This is because the cumulative energy increases monotonically without accounting for fluctuations in the seismic ground motion intensity, unlike the history of temperature at the sliding interfaces or the lead core of isolators. Accordingly, tests designed using the temperature as the performance criterion are recommended for use in specifications for testing. [ABSTRACT FROM AUTHOR]

Earthquake-prone regions have seen the resilience of traditional timber-framed masonry construction systems through previous seismic events. The post-earthquake studies show that these building systems have exceptional resilience to seismic activity and can endure multiple seismic events throughout their lifespan. This performance stands out from many contemporary constructions. Although there is a significant amount of evidence regarding the distinct behavior of these structures during earthquakes, there is a limited amount of meaningful quantitative experimental data on their seismic performance. This study showcases the findings of a series of half-scale shake table experiments carried out on a single-room; single-story timber frame filled with dry bond brick masonry. Two half-scale models were created and tested on a shaking table to investigate the seismic performance of timber framed masonry structural systems. One model was left without infill, while the other was infilled with dry bond brick masonry. To analyze the dynamic behavior, both models were exposed to random base excitation. Additionally, the models were tested with gradually increasing ground motion to study their response to seismic activity, following a method known as single ground motion record incremental dynamic analysis. The evaluation focused on the dynamic characteristics, including the assessment of natural frequencies, damping, mode shapes, and stiffness degradation. The stiffness decreased to 43% of the undamaged stiffness in the model with bricks and 62% of the undamaged stiffness in the model without infill. An assessment and evaluation were conducted on the peak acceleration and displacement responses, as well as the global hysteresis response. The acceleration response was significantly higher for the model with brick infill, with an amplification of 300%. In contrast, the model without infill had a lower amplification value of 150%. According to the findings of the study, it is evident that the timber framed structure exhibits a significant level of flexibility and deformability. Additionally, the structure's ability to dissipate energy increased as the peak ground acceleration of the input ground motion increased. [ABSTRACT FROM AUTHOR]

Steel racking systems are widely adopted for storage purposes: they are thin-walled structures composed of consecutive trusses, connected with beams on which the palletized goods are stored. Their geometry and structural configuration strongly depend on market and operator necessities, and, in modern applications, racks can also function as the supporting structure of the warehouse itself in the form of Rack Supported or High-Bay Warehouses. With the increase of the overall geometric dimensions and the global weight of the stored material, the seismic action becomes more relevant for the design. Along these lines, the development and experimental testing of a dedicated seismic design approach for ductile steel racks is here presented, with particular attention to Rack Supported Warehouses. This approach exploits the ductility of trusses introduced via the plastic ovalization mechanism of the diagonal-to-upright connections while a tailored capacity design is used to assure the elastic behaviour of the rest of the structure and to keep the brittle failure mechanisms at bay. [ABSTRACT FROM AUTHOR]

Backazimuthal variations in the shear wave splitting of core-refracted shear waves (SKS, SKKS and PKS phases, jointly referred to as X KS) at the Black Forest Observatory (BFO, Southwest Germany) indicate small-scale lateral and partly vertical variations of the seismic anisotropy. However, existing anisotropy studies and models for the nearby Upper Rhine Graben (URG) area in the northern Alpine foreland are mostly based on short-term recordings and by this suffer from a limited backazimuthal coverage and averaging over a wide or the whole backazimuth range. To identify and delimit laterally confined anisotropy regimes in this region, we carry out X KS splitting measurements at six neighbouring (semi-)permanent broad-band seismological recording stations (interstation distance 10–80 km). We manually analyse long-term (partly > 20 yr) recordings to achieve a sufficient backazimuthal coverage to resolve complex anisotropy. The splitting parameters (fast polarization direction |$\phi $|⁠ , delay time |$\delta t$|⁠) are determined in a single- and multi-event analysis. We test structural anisotropy models with one layer with horizontal or tilted symmetry axis and with two layers with horizontal symmetry axes (transverse isotropy). To account for lateral variations around a single recording site, modelling is compared for the whole and for limited backazimuth ranges. Based on this, we provide a 3-D block model with spatial variation of anisotropic properties. Based on delay times > 0.3 s and missing discrepancies between SKS and SKKS phases, which do not support lower mantle anisotropy, the found anisotropy is placed in the lithosphere and asthenosphere. The spatial distribution as well as the lateral and backazimuthal variations of the splitting parameters confirm lateral and partly vertical variations in anisotropy. On the east side of the URG, we suggest two anisotropic layers in the Moldanubian Zone (south) and one anisotropic layer in the Saxothuringian Zone (north). In the Moldanubian Zone, a change of the fast polarization directions is observed between the east and the west side of the URG, indicating different textures. At the boundary between the two terranes, an inclined anisotropy is modelled which may be related with deformation during Variscan subduction. Regarding the observation of numerous null measurements and inconsistent splitting parameters, especially (southwest of BFO) in the southern URG, different hypothesis are tested: scattering of the seismic wavefield due to small-scale lateral heterogeneities, a vertical a -axis due to a vertical mantle flow related to the Kaiserstuhl Volcanic Complex, as well as a different preferred orientation of the olivine crystals (not A-type, but C-type) due to specific ambient conditions (high temperature, water content). [ABSTRACT FROM AUTHOR]

This paper presents a new nonlinear viscous damping model implemented in the fibre where a constitutive rule is defined between the strain rates and the damping stresses. This model is developed for nonlinear dynamic analyses using distributed plasticity frame elements with fibre cross-sections. The model is proportional to the initial stiffness of the fibre material, but the maximum damping stress is limited to avoid local and global high damping forces and prevent them from decaying or taking negative values when the structure is in the inelastic range. The manuscript details the formulation used to find the fibre strain rates, the damping forces at each level of the structure and its implementation using the Newmark method. The predictions of the model are compared with the real response of a reinforced concrete structure tested on a seismic table under high demands. Additionally, a numerical case study addressing the inelastic response of a steel structure and sensitivity analyses are presented. [ABSTRACT FROM AUTHOR]

Comprehensive assessment of the active/passive seismic stability of shallow tunnel faces is an urgent and complex task. This work establishes a promising three-dimensional (3D) approach using upper-bound limit analysis to evaluate the active and passive seismic stability of shallow shield tunnel faces. The outcrop failure model and inside failure model are provided for active failure analysis. To capture the spatiotemporal variations of seismic loading, the pseudodynamic approach is employed to assess the limit active and passive support pressures. Comparisons with published studies and numerical simulations demonstrate that the proposed 3D approach greatly improves existing 2D results for limit active and passive support pressures. A detailed investigation is then conducted to analyze the effects of pseudodynamic parameters, surface surcharge, and buried depth on face stability of shallow tunnels. Finally, the proposed approach is further tested by conducting the seismic face stability analysis of Changsha Metro 2 tunnel based on actual seismic response. The results indicate that the surface surcharge has a greater influence on limit passive support pressure than limit active support pressure, and increasing of buried depth leads to a larger safety range of limit support pressure. Practical Applications: Active and passive face failure of shallow tunnels under earthquakes can endanger the safety of tunnels and ground surfaces, leading to severe casualties and property losses. Determination of limit support pressures under seismic forces is a critical task in shield tunnel construction. This work establishes an approach to assess 3D active and passive seismic stability of shallow shield tunnel faces. Time–space variations of seismic loading are incorporated to accurately determine limit active and passive support pressures using pseudodynamic approach. Effects of seismic parameters, surface surcharge, and buried depth on face stability of shallow tunnels are then presented and discussed. Finally, the proposed approach is tested by conducting the seismic face stability analysis of Changsha Metro 2 tunnel based on actual seismic response. The results indicate that surface surcharge has a greater influence on limit passive support pressure compared with limit active support pressure, and increasing buried depth leads to a larger safety range of limit support pressure. The proposed approach determines a safety range of limit support pressures more accurately for shallow shield tunnels during earthquakes. [ABSTRACT FROM AUTHOR]

The tailings microcrystalline foamed plate (TMF plate), produced from industrial waste tailings, has limited research regarding its use in high-performance building walls. Its brittleness under stress poses challenges. To improve its mechanical properties, a prefabricated light steel-tailings microcrystalline foamed plate composite wall (LS-TMF composite wall) has been proposed. This LS-TMF composite wall system integrates assembly, sustainability, insulation, and decorative functions, making it a promising market option. To study the in-plane performance of the composite wall, compression and seismic performance tests were conducted. The findings indicate that the light steel keel, steel bar, and TMF plate in the composite wall demonstrated good working performance. Strengthening the TMF plate enhanced the restraint on the light steel keel and improved the composite wall's compressive performance. Increasing the thickness of the light steel keel further improved the compressive stability. Under horizontal cyclic loading, failure occurred at the light steel keel embedding location. Increasing the strength of the TMF plate was beneficial for the seismic performance of the composite wall. This structural configuration—incorporating light steel keels, TMF plates, and fly ash blocks—enhanced thermal insulation and significantly improved in-plane stress performance. However, the splicing plate structure adversely affected the seismic performance of the composite wall. [ABSTRACT FROM AUTHOR]

Multi-axial real-time hybrid simulation (maRTHS) uses multiple hydraulic actuators to apply loads and deform experimental substructures, enacting both translational and rotational motion. This allows for an increased level of realism in seismic testing. However, this also demands the implementation of multiple-input, multiple-output control strategies with complex nonlinear behaviors. To realize true real-time hybrid simulation at the necessary sub- millisecond timescales, computational platforms will need to support these complexities at scale, while still providing deadline assurance. This paper presents initial work towards supporting (and is influenced by the need for) envisioned larger-scale future experiments based on the current maRTHS benchmark: it discusses aspects of hardware, operating system kernels, runtime middleware, and scheduling theory that may be leveraged or developed to meet those goals. This work aims to create new concurrency platforms capable of managing task scheduling and adaptive event handling for computationally intensive numerical simulation and control models like those for the maRTHS benchmark problem. These should support real-time behavior at millisecond timescales, even for large complex structures with thousands of degrees of freedom. Temporal guarantees should be maintained across behavioral and computational mode changes, e.g., linear to nonlinear control. Pursuant to this goal, preliminary scalability analysis is conducted towards designing future maRTHS experiments. The results demonstrate that the increased capabilities of modern hardware architectures are able to handle larger finite element models compared to prior work, while imposing the same latency constraints. However, the results also illustrate a subtle challenge: with larger numbers of CPU cores, thread coordination incurs more overhead. These results provide insight into the computational requirements to support envisioned future experiments that will take the maRTHS benchmark problem to nine stories and beyond in scale. In particular, this paper (1) re-evaluates scalability of prior work on current platform hardware, and (2) assesses the resource demands of a basic smaller scale model from which to gauge the projected scalability of the new maRTHS benchmark as ever larger and more complex models are integrated within it. [ABSTRACT FROM AUTHOR]

A self-centering isolated pier (SIP) with an elliptical rocking interface is proposed to enhance the seismic performance of bridge piers. Pseudostatic tests were conducted on two SIPs (one with and the other without tie bars) to study their damage patterns and hysteretic characteristics. Additionally, a finite-element model of a SIP was constructed to study the effect of SIP parameters on its hysteretic characteristics, such as the long radius of the ellipse, the ratio of the long to the short radii of the ellipse, the distance from the tie bar to the centerline of the pier, and the axial compression ratio. The results indicated that the pier bodies of the two SIPs are in the elastic stage. Increasing the long radius of the ellipse and axial compression ratio can enhance the hysteretic characteristics of the SIP. However, these larger values could lead to yield failure of the pier bottom. Furthermore, an increase in the ratio of the long to the short radii of the ellipse results in a progressively less plump hysteretic curve for the SIP, leading to a reduction in energy dissipation capacity. Nevertheless, an increase in this ratio can improve the self-centering ability of SIPs. The distance from the tie bar to the centerline of the pier has little effect on hysteretic characteristics of the SIP. [ABSTRACT FROM AUTHOR]

Computer vision enables a much more efficient monitoring system of structural behavior, compared to traditional methods. This derives from the fact that it allows the assessment of displacements in a vast number of points that can be processed to the estimate deformations, accelerations, and other key parameters at relevant cross‐sections. This paper proposes a computer vision‐based methodology, specifically designed for monitoring seismic tests conducted on a shaking table with a reduced‐scale model, using a single camera approach. This innovative methodology uses artificial targets with predefined color and geometry to optimize their detection and tracking. These targets are positioned at key points of the reduced model—“Moving Targets”—and at reference points of the seismic table—“Control Targets.” Videos are recorded during the seismic tests and the coordinates (in pixels) of the targets' centers are automatically detected and captured. Then, transformations are applied to each frame to compute the targets coordinates in millimeters and based on the differences between frames, to calculate the displacements of each target. The methodology was first calibrated with dynamic tests performed on a reduced‐scale model (1:33) of a prefabricated concrete shell, printed in acrylonitrile butadiene styrene (ABS), conducted on an educational shaking table. Afterwards, the methodology was validated with seismic tests performed on a 1:3 reduced model of a prefabricated concrete shell, produced according to the similitude theory to best reproduce the behavior of the corresponding prototype. It was demonstrated the ability of the methodology to monitoring seismic tests, enabling continuous tracking of the targets placed on a structure with complex geometry. [ABSTRACT FROM AUTHOR]

Masonry buildings of historical centres are usually organized within aggregates, whose structural performance against seismic actions is challenging to predict and constitutes still an open issue. The SERA—AIMS (Seismic Testing of Adjacent Interacting Masonry Structures) project was developed to provide additional experimental data by testing a half-scale, two-unit stone masonry aggregate subjected to two horizontal components of dynamic excitation. In this context, this paper investigates the reliability of the modelling approach and the assumptions adopted to generate a three-dimensional continuum finite element model. The work involves two stages, namely a blind pre-diction and a post-diction phase, and proposes a series of simulation analyses including a strategy to shorten the actual records and save computation costs. The study was performed to investigate the extent of uncertainty in modelling for such masonry aggregates in relation to the experimental outcomes. Pre-diction results were proven to be not accurate in terms of predicted displacements and damage patterns. The upgrades introduced for the post-diction analyses, including the calibration of the elastic modulus and the introduction of a non-linear interface between the two units, allowed to improve the outcomes, with reasonable results in terms of predicted base shear force, displacements along Y-direction and damage pattern for the non-linear stage. The overall approach showed to be appropriate for the structural analysis of existing masonry aggregates, but the accurate modelling of this type of structure remains challenging due to the high level of uncertainties. [ABSTRACT FROM AUTHOR]

This paper presents numerical simulations within the frame of the project SERA—AIMS (Seismic Testing of Adjacent Interacting Masonry Structures). The study includes blind pre-diction and post-diction stages. The former was developed before performing the shaking table tests at the laboratory facilities of LNEC (Lisbon), while the latter was carried out once the test results were known. For both, three-dimensional finite element models were prepared following a macro-modelling approach. The structure consisted of a half-scaled masonry aggregate composed by two units with different floor levels. Material properties used for the pre-diction model were based on preliminary tests previously provided to the participants. The masonry constitutive model used for the pre-diction study reproduced classical stress–strain envelope, whereas a more refined model was adopted for the post-diction. After eigenvalue analysis, incremental nonlinear time history analysis was performed under a unique sequence based on the given load protocol to account for damage accumulation. In the post-diction, the numerical model was calibrated on the data recorded during the shaking table tests and nonlinear dynamic analysis repeated under the recorded accelerogram sequence. The interaction between the two units was simulated through interface elements. Moreover, the timber floors were accounted following different strategies: not modelling or considering nonlinear wall-to-floor connections. Advantages and disadvantages are then analysed, comparing the pre-diction and post-diction results with the experimental data. Numerical results differ from the experimental outcomes regarding displacements and interface pounding, although a clear improvement is visible in the post-diction model. [ABSTRACT FROM AUTHOR]

Seismic damage due to pounding between adjacent buildings is often observed after significant earthquake events in old urban centers and globally recognized as a potential trigger for complete collapse. This is relevant for unreinforced masonry (URM) structures, which are particularly vulnerable to horizontal actions and seldom feature appropriate seismic detailing. Quantifying pounding damage between dynamically interacting URM buildings, however, is a challenging task, the details of which are difficult to simulate through analytical modeling alone. Numerical simulation of pounding failures, on the other hand, involves impact, separation and re-contact phenomena that often require advanced 3D micro-modeling strategies, often entailing a high computational expense that is not feasible when modeling the coupled seismic response of multiple buildings. To enable simulation of pounding damage in URM structures with relatively low computational cost, this paper investigates the use of a recently developed Macro-Distinct Element Model (M-DEM) approach. To this end, a M-DEM is herein used to simulate the shake-table biaxial pounding response of two dynamically interacting stone building prototypes, tested within the framework of the Seismic Testing of Adjacent Interacting Masonry Structures project sponsored by the Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe. Numerical results were obtained before the experimental test and then subsequently evaluated against the experimental results. The M-DEM predictions satisfactorily reproduced the measured base shear and interface opening, although they underestimated the floor displacement demand, especially in the transversal direction. Building on these encouraging outcomes, a post-test refined M-DEM model was also developed, and results are discussed alongside the lessons learned and proposed enhanced strategies to improve the quality of predictions. [ABSTRACT FROM AUTHOR]

We develop a 3D full waveform inversion (FWI) method based on dynamic time warping (DTW) to address the issue of cycle‐skipping, which can prohibit the convergence of conventional FWI methods. DTW globally compares data samples at different time steps in 2D matrices against the time shifts of waveforms. We introduce the concept of shape descriptors into softDTW, creating a soft‐shapeDTW objective function within our waveform inversion process to improve alignment accuracy. Additionally, including constraints from Sakoe‐Chiba bands in the inversion further enhances efficiency and overall performance. A synthetic test has shown that the soft‐shapeDTW inversion outperforms conventional waveform inversions in overcoming the cycle‐skipping challenges that arise from poor initial models. This method was applied to fit observed seismograms to reveal western Yunnan's crustal structure. Seismic waveforms were recorded by 88 broadband stations from 10 local earthquakes, which were then denoised using a continuous wavelet transform method. Generalized cut and paste waveform inversions were used to determine the source parameters of these seismic events. Our inversion well‐aligned various seismic phases in the selected time windows of seismograms, and the resolved velocity models well associate with local geological structure. Results suggest that the soft‐shapeDTW inversion offers a robust alternative to FWI, reducing the reliance on accurate starting models. Plain Language Summary: Crustal material properties are necessary information for geoscientists to investigate Earth's history, tectonic development, and seismic hazards. Imaging material properties based on time recordings of ground motion is an effective way to understand the strength and distribution of these materials. Geoscientists produce mathematical Earth models to approximate actual Earth structures when the predicted ground motion records from the models match observed records. We show that a mathematical technique from Information Science called Dynamic Time Warping (DTW) is suitable for pairing corresponding samples of predicted and observed ground motions. The set of time shifts estimated by DTW is progressively minimized to reach alignment. We constructed objective functions based on DTW in inversions to better fit most of the contents of ground displacement motions than conventional inversions. We tested this technique with seismic data from local earthquakes in western Yunnan province, southwest China, and produced an ideal crustal model for western Yunnan. The inversions improved by DTW promise to dramatically improve the processing of seismic waveforms to obtain information about the Earth. Key Points: We construct a three‐dimensional crustal structure in western Yunnan based on a full waveform inversion of local earthquakesConducting dynamic time warping to construct objective functions in full waveform inversions [ABSTRACT FROM AUTHOR]

Steel corrosion is by far the biggest durability issue for many reinforced concrete bridge structures worldwide. The columns in these bridges can be critical, especially for seismic resistance. In this study, glass-fibre-reinforced-polymer bars were investigated as an alternative to steel for sustainable and resilient bridge construction. As lateral reinforcement is more susceptible to corrosion, and structures fully reinforced with fibreglass bars display softer responses with lower shear and flexural capacity, fibreglass spirals and longitudinal steel reinforcement were used in the tested columns. The experimental programme included the design, construction and seismic testing of full-scale (508 mm diameter) and half-scale (356 mm diameter) columns. The other variables investigated were the axial load and the amount and spacing of spirals. For both column sizes, fibreglass spirals provided increasing confining pressure to the concrete core with increased deformations. For the full-scale columns, no adverse size effects were observed in comparison to the half-scale columns. The columns produced large ductility and energy dissipation. Results from selected representative specimens are presented here to establish the feasibility of using fibreglass spirals in circular bridge columns. Resilience can thus be built into new columns through innovative durable fibreglass lateral reinforcement, with similar if not superior behaviour to steel-reinforced columns. [ABSTRACT FROM AUTHOR]

Traditional ancient Tibetan buildings (TATBs) date back hundreds of years. The seismic performance of TATBs constructed with stones and mud was analyzed by utilizing structural subscale features (materials, walls, and structures). The key to load-bearing in TATBs is the three-leaf stone wall. Based on the mechanical properties of materials, compression tests and quasistatic static tests of walls, this paper confirms that the seismic resistance capacity of the three-leaf stone wall of TATBs is unable to meet Chinese standards. The aims of this study are to present the dynamic behavior of TATBs by shaking table tests. According to the experimental data, the transcendence intensity magnification calculation method is modified to calculate the seismic vulnerability of TATBs. The results show that when the peak acceleration of ground motion is 1.042 m/s2, 1.598 m/s2 and 2.881 m/s2, TATBs undergo slight damage, moderate damage, and severe damage, respectively. [ABSTRACT FROM AUTHOR]

This study focuses on detecting hard sandwiched soil layers using higher modes in the active multichannel analysis of surface waves (MASW) survey. The higher modes refer to the highest phase velocity spectrum over the fundamental mode in the dispersion image obtained from the active MASW test. Detection of the hard sandwiched soil layers can be challenging when the same magnitude of shear wave velocities ( V S) occur at two different depths in the V S profile obtained from fundamental modes. To address this issue, the dispersion curves were analyzed using surface wave partial derivative (SWPD) and finite element (FE) simulation for soil models. The depth variations of hard sandwiched soil layers were investigated experimentally and numerically, utilizing mode-mixing and mode-separation phenomena in the dispersion images. In cases of uncertainty in identifying the fundamental modes, the depth of the hard sandwiched soil layer was directly determined by half of the wavelength of the higher modes. Additionally, irregular soil profiles were examined using various multi-layer FE models and field MASW tests to detect the hard sandwiched soil layers of Vs values ranging from 700 to 800 m/s at depths ranging from 3 to 8 m. The advantages of Vs values using the higher modes were evaluated to detect the hard sandwiched soil layer compared to those using fundamental modes and downhole seismic test results. The hard sandwiched soil layers were correctly identified at depths of 4.8 m and 7.2 m in multi-layer soil models by focusing on the higher modes without analyzing the fundamental modes. [ABSTRACT FROM AUTHOR]

This study investigated the geotechnical and geophysical properties of the soil layers at the Missan combined-cycle power plant in Iraq. The data from 69 boreholes, including physical and chemical soil properties, were analyzed. The soil is primarily classified as silty clay with moderate to high plasticity, with some sandy layers. Since the Missan governorate is located in a seismically active region represented by the Iraq–Iran border, a study on the seismic properties of the site is also performed. Seismic downhole tests were conducted to determine wave velocities and dynamic moduli. The site was classified as soft clay soil according to FEMA and Eurocode 8 standards. Correlations for the physical and dynamic soil properties were evaluated. The correlations were executed via regression statistical analysis via Microsoft Excel software (2013). The results of the correlation equations and the coefficient of correlation R2 show that the physical correlations were considered medium to good correlations, whereas the dynamic soil correlations were perfectly correlated such that the R2 values were close to 1. This paper provides comprehensive data and soil property correlations, which can be valuable for future construction projects in the Missan area and similar geological formations. [ABSTRACT FROM AUTHOR]

This paper investigates a steel moment resisting frame (MRF) with a novel type of self‐centering (SC) base isolators, wherein superelastic shape memory alloy (SMA) U‐shaped dampers (SMAUDs) work as core components. A two‐story steel MRF model equipped with two SMAUD‐based isolators was designed and built in the laboratory, and a series of shake table tests were conducted to examine the dynamic behavior and seismic performance of the frame. Throughout all the tests, no interventions, such as repair or replacement of frame or isolator members, were done. Shake table test results demonstrated that the SMAUD‐based isolators could withstand multiple strong earthquakes with stable SC behavior. The utilization of SMAUD‐based isolators provided effective protection for the frame, enabling it to restore its original position with minimal structural damage. A numerical model of the tested steel MRF with SMAUD‐based isolators was also built. The results obtained from the numerical analyses agreed with those of the shake table tests satisfactorily. A comparative study of the seismic performance between the MRF with SMAUD‐based isolators and the MRF with traditional steel U‐shaped damper‐based isolators was also conducted in the shake table tests. The results showed that SMAUD‐based isolators not only inherit the isolation function of conventional isolators to protect the frame but also possess an SC ability to eliminate residual isolator deformation effectively. Moreover, SMAUD‐based isolators demonstrate remarkable resilience to withstand multiple strong seismic events without any need for repair or replacement. [ABSTRACT FROM AUTHOR]

To study the interaction mechanism of shaking table-test structure in shaking table test, an analytical model of shaking table array-test structure was established. Based on the analytical model, the influence of structure damping, frequency, and shaking table output on the accuracy of shaking table test was analysed. The analysis showed that compared with the actual frequency and theoretical response of the test structure, the measured structure frequency is decreased by 6.3%, and the peak value of seismic response of test structure is amplified 1.96 times. The interaction leads to 32% reduction of the waveform reproduction performance of shaking table. At the structure frequency and its surrounding frequency bands, the amplitude–frequency characteristic of shaking table is amplified 5.26 times, and the phase lag is 122.38° in the phase–frequency characteristic of shaking table. Based on the above results, it was indicated that the method that taking the output of shaking table as the input of structure will cause significant accuracy reduction when the interaction cannot be ignored. Finally, suggestions were given to improve the accuracy of shaking table test. [ABSTRACT FROM AUTHOR]

The present study proposes a new technique for retrofitting corroded beam–column joints (BCJs) using high‐strength fiber reinforced concrete (HSFRC) and stirrups replacement. The entire corrosion‐affected concrete was removed and replaced with HSFRC. The corroded reinforcing bars were cleaned and treated to resist the progression of the corrosion mechanism. The severely pitted stirrups were replaced with new stirrups. Four exterior BCJ specimens were tested under seismic loading to determine the effectiveness of the proposed retrofitting scheme. The efficacy of the proposed retrofitting scheme is determined in terms of the hysteresis response, stiffness degradation, cumulative energy dissipation, ductility, and damage index. A significant delay in the fracture of severely pitted reinforcing bars was experienced for the corrosion‐damaged retrofitted specimens compared to the corroded unretrofitted specimen. The cumulative energy dissipation of the corroded unretrofitted and corroded retrofitted specimens was 0.4 and 1.3 times that of the reference specimen, respectively, indicating the effectiveness of the retrofitting strategy, as both specimens had similar corrosion rates. The test results indicated that the proposed retrofitting technique effectively improved the seismic performance of the corrosion‐damaged BCJs. [ABSTRACT FROM AUTHOR]

The shear wall system with cast‐in situ concrete infilled walls has been widely used in high‐rise buildings due to its significant advantages in construction. In this paper, quasi‐static tests were conducted on the shear walls with and without cast‐in situ concrete infilled walls to analyze their failure modes, load‐bearing capacity, stiffness, energy dissipation capacity, and ductility. A simplified model of the shear wall with cast‐in situ concrete infilled walls was proposed based on the fiber element model in OpenSees. The test results showed that the shear wall specimens with cast‐in situ concrete infilled walls exhibited full‐section compression or tension failure, and the cast‐in situ concrete infilled walls did not show obvious damage. Compared with the shear wall without infilled walls, the overall stiffness, load bearing capacity, and energy dissipation capacity of the shear wall specimens with cast‐in situ concrete infilled walls improved, indicating better seismic performance than those without infilled walls. Comparison between the hysteresis and skeleton curves derived from the tests and those simulated by the proposed simplified model revealed errors within 15% for stiffness, yield bearing capacity, and ultimate bearing capacity for shear walls with cast‐in situ concrete infill walls, affirming the effectiveness and accuracy of the model. [ABSTRACT FROM AUTHOR]

Records of pile lengths are not available for several hundred high-mast light towers (HMLTs) throughout the state of Minnesota. The foundation systems, typically steel H-piles or concrete-filled steel pipe piles connected to a triangular concrete pile cap, risk overturning in the event of peak wind loadings if the foundation piles are not sufficiently deep to provide the designed uplift capacity. Without prior knowledge of the in situ pile lengths, an expensive tower foundation retrofit or replacement effort would need to be undertaken. However, the development of a nondestructive screening tool to determine the in situ pile length—compared with replacing or retrofitting all towers with unknown foundation geometries—would potentially provide significant cost savings. The main goal of the research is the development of nondestructive evaluation testing techniques for determining in situ pile lengths using steady-state vibration and hammer-impact seismic testing. The foundation testing protocol involves (1) a preliminary site investigation to determine the shallow subsurface geometry and orientation of the foundation pile cap, (2) the use of seismic cone penetrometer (SCP) attached to a cone penetration test rig to capture the induced steady-state and impact waveforms, and (3) data-driven analysis of field testing results to determine the pile lengths. [ABSTRACT FROM AUTHOR]

Interaction between masonry infill walls (MIWs) and a main structural system can impact the overall structural performance. However, there is no test to investigate the impact of MIWs on self-centering prestressed concrete (SCPC) frames, nor has there been a probabilistic performance evaluation considering the coupling effects of peak interstory drift ratio (PIDR) and residual interstory drift ratio (RIDR). This study compares the seismic performance of SCPC frames with and without MIWs through quasi-static tests and seismic risk assessment under mainshock–aftershock (MSAS) sequences. To begin, quasi-static tests on one-story SCPC frames with and without MIWs are performed to assess their seismic performance. A numerical simulation method for the SCPC frame with MIWs is then proposed and validated. Following that, the seismic performance of four multistory SCPC frames with and without MIWs is investigated under MSAS sequences at the maximum considered earthquake level. Finally, the seismic vulnerability assessment, considering the coupling effect of PIDR and RIDR under MSAS sequences, is conducted. The results indicate that cracks on the MIW present diagonal stepped cracks, and the MIW does not cause damage to the SCPC frame. When the MIW is damaged, the RIDR of the SCPC-MIW frame increases significantly; when the crack development is stable, the RIDR increases slowly as the interstory drift increases but remains at a very low level. Besides, when the MIW is damaged, an obvious deformation concentration effect occurs on the SCPC-MIW frame. The SCPC-MIW frame has a lower probability of exceeding the immediate occupancy level P(IO) than the SCPC frame, but it has a higher probability of exceeding the repairable level P(RE) when the seismic intensity is relatively small. Overall, the P(IO) and P(RE) of the SCPC and SCPC-MIW frames are higher under MSAS sequences than under MS-only sequences, except for the SCPC25 frame. [ABSTRACT FROM AUTHOR]

In this study, nonlinear isoparametric shell elements with variable edge order and moving nodes from CBAL4M to CBAL12M were developed and integrated into FINITE. Specific mapping and surfaces for two‐dimensional isoparametric shell elements, shape functions, and their derivatives are presented. The advantage of the developed shell element is that it can represent not only the smeared reinforcement on the wall and slab but also the discrete special reinforcement that is important for crack propagation in the nonlinear simulation of RC structures. With the advantage of movable nodes, the discrete reinforcement can be effectively covered and the position of the discrete reinforcement can be determined. When modelling reinforced concrete structures dominated by shear walls, the use of variable edge orders at the slab‐wall interfaces where high stresses or forces are expected reduces the calculation time and capacity by using an optimal number of nodes for hybrid modelling. Nonlinearity is considered only in the form of material nonlinearity with a stress‐strain curve, tension stiffening, and cracking including crack rotation. The analytical model is validated by comparing the results at the element level of the Vecchio and Collins test panels at the University of Toronto and at the structural level of the five‐story shear wall building with staggered openings at the University of Michigan. Nonlinear hybrid simulations of 2D and 3D models of 2‐story and 5‐story shear wall‐dominated RC buildings are investigated with the developed element considering ultimate load curves, deflection shapes, crack patterns, stress distributions, and 3D effects and force mechanisms. For this purpose, a three‐story scaled test model was constructed and tested to simulate the seismic behavior. The test results are also compared with the analytical results of SAP2000 and the developed nonlinear shell element. The seismic capacity of the test model and the analytical models was similar at 31 tons. The developed element can be effectively used for modelling and nonlinear hybrid simulation of RC buildings and can also be applied to prestressed concrete structures for tendon modelling. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the ability of propolis‐coated ureteric stents to solve complications, especially urinary tract infections (UTIs) and crusting, in patients with long‐term indwelling ureteric stents through antimicrobial and anti‐calculus activities. Materials and Methods: Polyurethane (PU) ureteric stents were immersed in the ethanol extract of propolis (EEP), a well‐known antimicrobial honeybee product, and subjected to chemical, hydrophilic, and seismic tests. The antimicrobial activity of the EEP coating was then examined by in vitro investigation. Proteus mirabilis infection was induced in rats within uncoated and EEP‐coated groups, and the infection, stone formation, and inflammation were monitored at various time points. Results: The characterisation results showed that the hydrophilicity and stability of the EEP surface improved. In vitro tests revealed that the EEP coating was biocompatible, could eliminate >90% of bacteria biofilms attached to the stent and could maintain bacteriostatic properties for up to 3 months. The in vivo experiment revealed that the EEP‐coating significantly reduced the amount of bacteria, stones, and salt deposits on the surface of the ureteric stents and decreased inflammation in the host tissue. Conclusions: Compared with clinically used PU stents, EEP‐coated ureteric stents could better mitigate infections and prevent encrustation. Thus, this study demonstrated that propolis is a promising natural dressing material for ureteric stents. [ABSTRACT FROM AUTHOR]

To quantify the seismic effectiveness of the most commonly used fishing line tie up method for securing museum collections and optimize fixed strategies for exhibitions, shaking table tests of the seismic systems used for typical museum collection replicas have been carried out. The influence of body shape and fixed measure parameters on the seismic responses of replicas and the interaction behavior between replicas and fixed measures have been explored. Based on the results, seismic effectiveness evaluation indexes of the tie up method are proposed. Reasonable suggestions for fixed strategies are given, which provide a basis for the exhibition of delicate museum collections considering the principle of minimizing seismic responses and intervention. The analysis results show that a larger ratio of height of mass center to bottom diameter led to more intense rocking responses. Increasing the initial pretension of fishing lines was conducive to reducing the seismic responses and stress variation of the lines. Through comprehensive consideration of the interaction forces and effective securement, it is recommended to apply 20% of breaking stress as the initial pretension. For specific museum collections that cannot be effectively protected by the independent tie up method, an optimized strategy of a combination of fishing lines and fasteners is recommended. [ABSTRACT FROM AUTHOR]

Replaceable flexural and shear fuse-type coupling beams are used in hybrid coupled shear wall (HCSW) systems, enabling concrete buildings to be promptly recovered after severe earthquakes. This study aimed to analytically evaluate the seismic behavior of flexural and shear fuse beams situated in short-, medium- and high-rise RC buildings that have HCSWs. Three building groups hypothetically located in a high seismic hazard zone were studied. A series of 2D nonlinear time history analyses was accomplished in OpenSees, using the ground motion records scaled at the design basis earthquake level. It was found that the effectiveness of fuses in HCSWs depends on various factors such as size and scale of the building, allowable rotation value, inter-story drift ratio, residual drift quantity, energy dissipation value of the fuses, etc. The results show that shear fuses better meet the requirements of rotations and drifts. In contrast, flexural fuses dissipate more energy, but their sectional stiffness should increase to meet other requirements. It was concluded that adoption of proper fuses depends on the overall scale of the building and on how associated factors are considered. [ABSTRACT FROM AUTHOR]

The bidirectional ductile end diaphragm concept uses energy-dissipating buckling restrained braces (BRB) as fuses located at the end of a bridge superstructure's floating spans. This system using BRBs can provide seismic resilient and damage-free bridges fully operational immediately after an earthquake. A shake-table testing program was conducted to subject a 1/2.5-scale specimen to series of ground motions. The specimen tested represents one span of a five-span bridge having BRBs connected to the abutment and the pier next to it. The purpose of these tests was to experimentally validate proposed connection details when subjected to the three-dimensional (3D) displacement histories (compared with the axis of the BRBs) that resulted from bidirectional ground motions and the fact that the connections must accommodate inclined BRB layouts. The test protocol included earthquake displacement histories that represent design demands, cycles of thermal excitations, and (to eventually make the BRBs fail) extreme motions. The testing program validated the effectiveness of the proposed concept and the ability of BRBs to sustain multiple ground motions before failure. [ABSTRACT FROM AUTHOR]

A series of model tests about vibroflotation were conducted to investigate soil property change on silica sand foundations, especially for earthquake-resistant behavior. First, the process of double-point vibroflotation was investigated with a simulative vibrator system. Thereafter, shaking table tests were conducted to evaluate seismic responses. The results illustrated that the relative density was significantly enhanced after the first vibratory period, with the highest enhancement appearing at the vibropoint in the plane and the middle layer along the depth. As for the seismic tests, the excess pore pressure ratios show that the vibroflotation can apparently improve the liquefaction-resistance capacity of the silica sand foundation. Moreover, the shear stiffness of the unconsolidated foundation decreases distinctly under 0.2g earthquake motion, while the consolidated foundation remains capable of transmitting acceleration. Inflicting white noise before the any earthquake motion and after 0.2g earthquake, the result shows that the predominant frequency of unconsolidated foundation decreases apparently. The dynamic shear stress–strain curves were compared, while the development law of the time history was also investigated. These results demonstrated that this method can obviously prevent the shear stiffness attenuation. To sum up, the vibroflotation compaction method can make a great densification and increase the earthquake-resistant capacity. [ABSTRACT FROM AUTHOR]

In this paper, a new foam concrete-extruded polystyrene composite wall panel (FCPW) is proposed. In order to investigate the response of these wall panels to the loading conditions that may occur during an earthquake event, a total of three specimens were designed in this study to study the seismic performance of the wall panels with different sizes of cyclic loads applied to them. By analyzing the seismic parameters such as hysteresis curve, skeleton curve, ductility and stiffness degradation factor of the wall panels, it is concluded that the wall panels have good seismic performance. Both the test phenomenon and damage mechanism indicate that shear damage is the damage form of the specimen. Comparing the specimens, it can be seen that the height-to-width ratio and the strength of the specimen itself have obvious effects on the seismic performance. The larger the height-to-width ratio is, the larger the ductility is and the better the seismic performance is. The smaller the thickness of the concrete is, the smaller the ductility is and the worse the seismic performance is. This study helps to update the iteration of composite wall panels composed of extruded plastic board and concrete and provide a reference for future research. [ABSTRACT FROM AUTHOR]

Fine-grained sand deposits in subtropical regions are valued for their low settlement percentages, providing high load-bearing capacity for foundations. Despite existing literature, certain behaviors of these deposits, particularly under cyclic loading in unsaturated conditions with stiffness control, still need to be better understood. Given the potential for shaft friction degradation in cyclically loaded axial piles, this gap is critical. This paper comprehensively investigates the mechanical properties of PE-Sand from a Southern Brazil deposit under cyclic loads, integrating laboratory and field analyses. Characterization involved granulometric, specific gravity, consolidation, matric suction, microscopic, mineralogical, and chemical tests. Uncommon unsaturated direct shear tests were performed, evaluating shear interface degradation under one-way and two-way cyclic loads. Standard penetration and seismic piezocone tests at 25m depth contrasted field properties. Findings identified uniform micaceous quartz sand. A novel conceptual model for PE-sand cohesion emerged from stiff-direct shear tests. Cyclic tests revealed heightened interface degradation with fewer cycles at increased load amplitudes. Fatigue results converged to a cumulative damage value, signifying material criticality limiting sand-sand interface resistance. Field exploration confirmed a heterogeneous sand deposit with geotechnical properties akin to laboratory findings. This study contributes nuanced insights into fine sand behavior under cyclic loading in unsaturated conditions, bridging gaps in existing knowledge. [ABSTRACT FROM AUTHOR]

Given the widespread use of lightweight composite wall panels in building structures, it is crucial to comprehend their seismic performance. This paper proposes a new lightweight concrete composite exterior wallboard (LCEW) featuring truss-type thermal barrier connectors (TBCs). Through the proposed static test, the damage morphology and hysteresis curve of the specimen are obtained; the hysteresis characteristics, skeleton curve, stiffness degradation, etc., are investigated; and the damage modes are summarized. The results demonstrate that the steel frame structure can effectively adapt to the use of LCEW, resulting in an approximately 20% increase in the frame structure's bearing capacity. Second, the wall panels with a uniform transverse arrangement of TBCs could not perform as well, as they could only delay the crack opening. To give full play to its effect, it should be combined with the direction of the main tensile zone of the wall panels. Meanwhile, the sliding gusset connections effectively released the frame action at the system level. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study conducted on the behavior of drop-in anchors in uncracked concrete slabs. Both seismic (cyclic) load tests and static load tests to collapse are performed on drop-in anchors subjected to tension or shear forces. Three different anchor sizes are subjected to seismic qualification testing, followed by a static load test to collapse. The test results confirm the capability of the tested anchors to sustain simulated pulsating seismic tension and shear loading with frequency ranges between 0.1 and 2.0 Hz. It was observed that no tension failure occurred at the end of the cyclic load tests for all the tested anchors, and their residual inelastic maximum displacement at the end of the cyclic tension test was relatively small. Moreover, the experimental results show that the anchors' ultimate capacities are higher than those specified by the anchor manufacturer. Finally, the anchors' experimental pullout shear capacities are compared with the failure prediction equations in the literature and design codes. It is found that the theoretical models provide a conservative prediction of the concrete breakout of anchors in tension compared to the experimental ultimate loads. The coefficient for pry-out strength (kcp) equal to 2 or slightly smaller than 2 is likely to predict a better pry-out capacity with the experimental results compared to the application of the high conservative value of kcp equal to 1, as given in the code. [ABSTRACT FROM AUTHOR]

Borehole strain gauges play a crucial role in geophysical, seismological, and crustal dynamics studies. While existing borehole strain gauges are proficient in measuring horizontal strains within vertical boreholes, their effectiveness in capturing vertical and oblique strains is limited due to technical constraints arising from the cylindrical probe's characteristics. However, the accurate measurement of three-dimensional strain is essential for a comprehensive understanding of crustal tectonics, dynamics, and geophysics, particularly considering the diverse geological structures and force sources within the crustal medium. In this study, we present a novel approach to address this challenge by enhancing an existing horizontal-component borehole strain gauge with a bellows structure and line strain measurement technology to enable vertical and borehole oblique strain measurements. Integrating these enhancements with horizontal strain measurement capabilities enables comprehensive three-dimensional borehole strain measurements within the same hole section. The system was deployed and tested at the Gongxian seismic station in Sichuan Province. Clear observations of solid tides were recorded across horizontal, oblique, and vertical measurement units, with the tidal morphology and amplitude being consistent with the theoretical calculations. The achieved measurement sensitivity of 10-10 meets the requirements for borehole strain measurement, enabling the characterization of three-dimensional strain states within boreholes through association methods. [ABSTRACT FROM AUTHOR]

To realize the prefabricated structure of special‐shaped concrete‐filled steel tubular (CFST) column frame and enhance the level of indoor room utilization, this paper proposed a novel prefabricated frame with special‐shaped CFST columns and H‐shape steel beams connection with side plate. To investigate seismic behavior of this prefabricated frame structure, a 2‐story and 2‐bay CFST frame specimen was fabricated and tested under reversed cyclic loading. The failure mode, hysteresis behavior, degradation of lateral stiffness and bearing capacity, ductility and energy dissipation were analyzed. Experiment results indicated that failure mode presented strong columns and weak beams. Hysteresis curve of frame showed fully shuttle‐shaped. The mean story drift angle was 1/36 at ultimate stage. Equivalent viscous damping coefficient was 0.038–0.464. The bearing capacity degradation was relatively gentle, but the overall stiffness degradation was more obvious. It suggested that the frame had proper seismic and energy dissipation property. After the test, the seismic property of test frame was further investigated through the numerical simulation approach. The failure mode and skeleton curve obtained from the simulation were nearly consistent with test results, indicating that numerical analysis results were precise and with high reference meaning. [ABSTRACT FROM AUTHOR]

A shaking table test of a 1/60 scale cross-fault bridge model considering the effects of soil–bridge interactions was designed and implemented, in which the bridge model was placed in two individual soil boxes to simulate the bridge across a strike-slip fault. Three seismic ground motion time-histories with permanent displacements were selected as input excitations to investigate the influence of seismic ground motions with different frequency characteristics on the seismic response of the testing soil–bridge model. The one-side input method was used to simulate the seismic response of bridges across faults. The seismic responses of the soil and bridge in terms of acceleration, strain, and displacement were analyzed. The test results show that the one-side input method can simulate the seismic response of the main girder displacements well and the displacements and strains of piers and piles of the bridge structure spanning a fault. The strain responses at near-fault pile foundations are much larger than those farther away from the fault. Compared with other bridges, the cross-fault bridge is more prone to torsional and displacement responses during earthquakes. Surface fault rupture can lead to permanent inclination of the bridge piers, which should be paid more attention to in the practical engineering design of the bridges. Soil–bridge interactions can suppress the amplification effect of soil on ground motions. The test results can provide a reference for future research and the design of cross-fault bridges. [ABSTRACT FROM AUTHOR]

This study aims to characterize the frequency magnitude distribution factor (b-value) for Nepal and its surrounding area-thereby focusing on conducting spatiotemporal and depth-wise analysis of b-value fluctuations before the November 9, 2022 earthquake of magnitude MW 6.3. Using the non-parametric Kolmogorov–Smirnov (K–S) test, earthquake events with a magnitude MW ≥ 3.5 reported between 1900 and 2022 from the earthquake catalog compiled by the International Seismological Centre (ISC) and the United States Geological Survey (USGS) were analysed. We determined the minimum magnitude of completeness (MC) using the Maximum Curvature Method (MAXC). Furthermore, we divided the study region into equal-sized square grids and computed b-values using the maximum likelihood technique for each grid. We analysed the relationship between the b-value and seismic parameters such as focal depth, seismic moment release, and radon gas anomalies, along with their spatial correlations and patterns. Results indicate minimal seismicity in the lower crust compared to the upper crust and lead to establish an inverse relationship between the b-value and seismic moment release. We established plausible correlations between temporal variations of the b-value and variations in radon gas concentration as an earthquake precursor in different medium. Additionally, we utilized the Gumbel extreme value theory to estimate the mean return period, the most likely maximum yearly earthquake, and probabilities of recurrence of different magnitudes across different periods for credible seismic hazard analysis. We found the most likely maximum yearly earthquake for the region to be 5.53, with a mean return period of 5 years for the November 9, 2022 earthquake. The mean return period of earthquakes with magnitudes ranging from 5.0 to 6.5 (MW) was estimated to be 5–10 years. These findings contribute to a better understanding of the intricate seismotectonic configuration of the region and serve as earthquake precursors for potential future destructive earthquakes. [ABSTRACT FROM AUTHOR]

Comprehensive field investigations into the axial cyclic loading behaviour of open steel pipe piles driven and aged in low-to-medium-density chalk identify the conditions under which behaviour is stable, unstable or metastable. Post-cycling monotonic tests confirmed that stable cycling enhanced pile capacity marginally, while unstable cases suffered potentially large losses of shaft capacity. Metastable conditions led to intermediate outcomes. The patterns by which axial deflections grew under cyclic loading varied systematically with the normalised loading parameters and could be captured by simple fitting expressions. Cyclic stiffnesses also varied with loading conditions, with the highest operational shear stiffnesses falling far below the in situ seismic test values. The monotonic and cyclic axial responses of the test piles were controlled by the behaviour of, and conditions within, the reconsolidated, de-structured, chalk putty annuli formed around pile shafts during driving. Fibre-optic strain gauges identified progressive failure from the pile tip upwards. Large factors of safety were required for piles to survive repetitive loading under high-level, two-way conditions involving low mean loads, while low-amplitude one-way cycling had little impact. A simple 'global' prediction procedure employing interface shear and cyclic triaxial tests is shown to provide broadly representative predictions for field behaviour. [ABSTRACT FROM AUTHOR]

The nondestructive spectral analysis of surface waves (SASW) technique determines the shear wave velocities along the wide wavelength range using Rayleigh-type surface waves that propagate along pairs of receivers on the surface. The typical configuration of source-receivers consists of a vertical source and three vertical receivers arranged in a linear array. While this approach allows for effective site characterization, laterally variable sites are often challenging to characterize. In addition, in a traditional SASW test configuration system, where sources are placed in one direction, the data are collected more on one side, which can cause an imbalance in the interpretation of the data. Data interpretation issues can be resolved by moving the source to opposite ends of the original array and relocating receivers to perform a second complete set of tests. Consequently, two different Vs profiles can be provided with only a small amount of additional time at sites where lateral variability exists. Furthermore, the testing procedure can be modified to enhance the site characterization during data collection. The advantages of performing SASW testing in both directions are discussed using a real case study. [ABSTRACT FROM AUTHOR]

The seismic performance of arch bridges is dependent on the strength of bridges and the built-on soil site types. To investigate the influence of soil-structure interaction (SSI) on the seismic response of an arch-foot arch bridge with a sand-gravel soil site, several shaking-table tests for a 1/90 downscaled arch-foot model placed on sand-gravel soil were conducted based on the engineering prototype of the third Pingnan Bridge with a long-span concrete-filled steel-tube (CFST) arch bridge. The test results showed the following: (1) The seismic acceleration response of both the sand-gravel soil site and arch foot were amplified, which is related to both the non-linear dynamic behavior of sand-gravel soil and frequency-spectrum characteristics of the input seismic waves. (2) The sliding displacement of the arch foot under strong ground motions increased accompanied with a settlement of the soil surface. However, the safety risk of the arch foot may be underestimated in seismic design. (3) The dynamic shear stress-strain loops of sand-gravel soil exhibited a high-energy dissipation capacity, and the energy-transfer mechanism at the interface between the model soil and arch foot was integrated. The results obtained are expected to provide insights into the dynamic interaction behavior of the gravel soil and arch bridge systems and the seismic design of arch bridges built on sand-gravel soil sites in practical engineering. [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]

The choice of stiffness profile can be crucial in a site response analysis. This research aims to study site response predictions at the large-scale seismic test site in Lotung, Taiwan, employing three different approaches to choosing the stiffness profile in nonlinear and equivalent linear analyses. These approaches consider point average, layer average, and deposit average stiffness profiles. One strong and one weak earthquake event recorded at the site are simulated with these three stiffness profile approaches. Moreover, the stiffness profiles are tested under sets of seven modified real input motions (selected from the European Strong-Motion Database) at various seismic intensity levels. The results indicate that the different stiffness profiles have a minimal effect on the nonlinear site response predictions, in particular for input motions having a PGA greater than or equal to 0.05 g. The spectral acceleration values and PGA and shear strain profiles from nonlinear site response analyses change negligibly when using different approaches to derive the stiffness profile. In the equivalent linear site response analysis, the spectral acceleration predictions are strongly influenced by the stiffness profile approach, regardless of the PGA level of the input motions. The stiffness profile has a more significant role in equivalent linear site response analysis than in nonlinear site response analysis. Therefore, the point average stiffness profile should be used in equivalent linear site response analysis. [ABSTRACT FROM AUTHOR]