Large-scale multi-axial loading structural test equipment (LMLSTE) is a very important tool to evaluate the seismic capacity of complex structural systems and components. This promotes the continuous development of LMLSTE and implementation all over the world. The structural test techniques are also developed together with LMLSTE. The two complement each other and promote each other. This study provides an overview of the current development of LMLSTE: basic components, principles of operation, performance indicators, as well as its applications in structural tests. To introduce the developmental context of LMLSTE, they are discussed separately into four categories: multi-axial sub-assemblage testing (MAST), load and boundary condition box (LBCB), pressure-shear machine, and multi-usage structural testing (MUST) system. The key technical challenges in LMLSTE are summarized, including coordinated control of multi-axial with different stiffness, multi-input and multi-output decoupling control, actuator redundancy constraints, and accurate force measurement. Finally, the potential LMLSTE are presented.

In the last two–three decades, glass facades have gained more popularity due to their highly impactful esthetic and sustainable applications. However, their constitutive glass components are rather vulnerable and require proper analysis strategies to design them efficiently in structural terms, especially against extreme loads, such as earthquakes. To save time and costs, numerical approaches and simulations represent a powerful and versatile technique that can be used to predict the seismic behavior of glass facades under several loading and boundary conditions. Besides that, the lack of specific guidelines to support the model assembly and calibration for these analyses makes these steps uncertain and rather challenging. Among other open issues, this study collects and revises a selection of literature studies that emphasized the use of numerical simulations for glass facades subjected to earthquakes. Attention is focused both on framed glass facades and frameless (point-fixed) solutions. From the literature analysis, several modeling strategies emerge. Most importantly, difficulties and uncertainties in modeling complex glass facades are pointed out, especially with regard to the geometrical and mechanical optimization and the introduction of robust simplification approaches. It is observed that secondary components, such as setting blocks or gaskets, are often disregarded, which can have major consequences for the structural analysis and detailing of seismic effects in glass components.

Climate change and human activities have caused significant fluctuations in groundwater tables in cities worldwide, which in turn substantially influence the seismic response of underground structures in liquefiable ground. This study performs numerical analysis on the influence of groundwater depth on the response of underground structures subjected to seismic loading for typical soil profiles. The liquefiable soil is modeled using the CycLiq constitutive model. Numerical results reveal that shallow-depth groundwater table rise increases maximum drift ratio and bending moment when liquefiable soil passes through the underground structure, but reduces these responses when liquefiable soil exists only above or below the structure. The presence of liquefiable soil beneath the structure leads to significant uplift as the groundwater table rises. The variation of the drift ratio is influenced by the inertia, initial stiffness, and softening of the surrounding soil. The predominant frequency and peak ground acceleration of the input motion and underground structure depth significantly affect the dependency of the drift ratio and the vertical displacement on groundwater table change. These findings highlight the critical importance of considering groundwater table changes in seismic design and risk assessment of underground infrastructure.

Spatial combination rules for multi-component seismic excitation have been developed mainly to account for the effects of the uncertainty in the incident angle of excitation on the response amplitudes of asymmetric buildings. These combination rules become redundant for symmetrical buildings, and the unidirectional analysis based on commonly used types of response spectra is unable to predict the maximum response amplitudes under bidirectional excitation. This paper proposes to utilize the concept of the Critical Response Spectrum (CRS) to accurately predict the maximum response of simple symmetric buildings using only one-dimensional response spectrum analysis (RSA) based on the CQC method. As the design spectra are not readily available in terms of CRS, preliminary empirical scaling factors have been developed to obtain a reasonable approximation to CRS from the RotD50 spectrum, in terms of which the NGA-West2 GMPEs are expressed. The validity of both the actual and the approximate CRS has been established by comparing the maximum response quantities of two distinct six-storey symmetrical steel building models with the exact time-history analysis (THA) for a large data set of 56 pairs of horizontal accelerograms of real earthquakes with widely differing characteristics. The mean percentage errors have been found to be much less within about ±10% compared to the unacceptable underestimation of up to about −50% in using the other traditional types of response spectra (viz., geometric mean, envelope, major principal, and RotD50).

The moment-resisting reinforced concrete (RC) frame infilled with masonry walls is a common form of construction for low- to medium-rise buildings. The importance of considering the infill masonry walls (IMW) in seismic analysis is accentuated due to the interaction between infills and the surrounding frame. Several analytical IMW models have been proposed to model IMW as equivalent diagonal struts, and the appropriateness of those models has been justified through experimental and numerical calibrations. However, the reliability of those analytical models is not well substantiated. Therefore, the reliabilities of five different analytical models have been evaluated herein using the First-Order Reliability Method (FORM). The stochastic uncertainties involved in predicting the in-plane capacities of IMW-RC frames have been incorporated in the reliability analyses. Subsequently, reliabilities of IMW models have been ascertained using experimental data sets compiled at two different scales, namely (1) single story–single bay and (2) multistory IMW-RC frames. 120 experimental data sets of single story–single bay IMW-RC frames tested under in-plane loading and three multistory IMW-RC frames tested on shake-tables were used to assess the reliabilities of IMW models. The results showed that the IMW models considered have predicted the in-plane behavior of IMW-RC frames (single or multistory) to certain levels of accuracy. The predicted reliability indices (β values) of the models vary between 1.03 and 4.13. The reliabilities differ when different aspects of the predictions are being considered, such as peak or ultimate load and drift capacities of single story–single bay frames or base shear and story drift of multistory frames. Therefore, depending on the requirement (strength- or displacement-based design), the IMW models should be selected appropriately to carry out the seismic analyses of IMW-RC buildings.

The seismic vulnerability of cable-stayed bridges, as crucial transportation nodes with numerous components, has always been a focal point of concern. The paper introduces a seismic resilience assessment method for cable-stayed bridge systems with the consideration of multi-component based on Pair Copula and Vine Copula models. In this approach, the seismic vulnerability of the multi-component cable-stayed bridge system is calculated by iteratively applying Pair-Copula and Vine-Copula models, and the resilience of the bridge is assessed based on these results. A real cable-stayed bridge is used as an example, where the resilience assessment results obtained through this method are compared with those derived from the first-order bound method, allowing the effectiveness of this approach to be verified and its applicability demonstrated. It is indicated that this method is highly suitable for capturing the vulnerability of cable-stayed bridge systems, enabling a more practical resilience assessment to be provided. A theoretical reference for future seismic resilience assessments of cable-stayed bridges is thus offered by this method.