ABSTRACT Large displacements are expected to occur in existing code-compliant steel moment-resisting frames during a severe earthquake, affecting the functionality of buildings. This study investigated the use of buckling-restrained braces for controlling the displacement response and ensuring an occupiable performance level of the structures. A design procedure for the braces based on the energy balance concept is proposed, where the hysteretic energy demand of the frame before and after attaching the braces is equated. Time-history analysis results show structures designed using the proposed procedure satisfied the targeted performance level, and no significant change in peak floor acceleration response was observed.

ABSTRACT The aim of this study was to develop an innovative deep learning based intelligent software (DamageNet) and its mobile applications to classify seismic damage of Reinforced Concrete (RC) elements. Images of 2455 damaged elements that have been exposed to different destructive earthquakes were collected from the “datacenterhub” database. The DamageNet algorithm has been compared with the pretrained convolutional neural networks (CNN) algorithms (VGG16, ResNet-50, MobileNetV2 and EfficientNet) according to performance metrics. With the other models, a maximum test success of 89% was achieved, while with DamageNet a test success of 92% was achieved in damage classification. The mobile application developed based on the DamageNet model was tested in the field after the earthquakes (Mw:7.7 and Mw:7.6) in Kahramanmaraş/Turkey and classification success of 88% was obtained.

ABSTRACT The effects of evolutionary Arias intensity are thoroughly investigated based on ground motion simulation and nonlinear dynamic response. A new methodology is developed to generate a series of spectral-equivalent synthetic motions with different energy accumulation paths using wavelet packets. Systematic studies are performed on dynamic responses of hysteretic systems and liquefiable grounds using the simulated motions and actual recordings. An attempt is made to develop the relationship between liquefaction-induced deformation and shaking intensity rate which is used to quantify the rate of Arias intensity accumulation. The results indicate the need of considering evolutionary Arias intensity in nonlinear dynamic analysis.

ABSTRACT To investigate the correlationf between residual drift and remaining seismic capacity, 24 reinforced concrete pier specimens were subjected to lateral load reversals. By normalizing the specified drift against the value at specimen failure, the normalized residual drift exhibits a strong correlation with the normalized lateral drift, thereby providing a predictive model for residual drift. After determining the remaining seismic capacity derived from energy dissipation, a linear correlation was established between the normalized residual drift and the remaining seismic capacity. Consequently, normalized residual drift was selected as a performance indicator for seismic assessment, enabling the quantitative determination of structural damage states.

ABSTRACT A new cable-damper stopper equipped for Coal-Fired Thermal Power Plants (CFTPPs) was proposed in our previous paper, where a series of shaking table tests were carried out to investigate its seismic performance, so this paper aims to reveal the working mechanism of the stopper from the theoretical and numerical simulation aspects. The stopper is composed of three main components, i.e. a steel cable, a steel block and a viscous damper. First, the nonlinear restraint stiffness of the steel cable to the boiler was derived; second, the critical damping of the stopper, which makes the vibration of the boiler decay exponentially with no oscillation, was derived; third, an iterative method was proposed to globally tune the CFTPP structure, which makes it possible to obtain the optimal parameters of the cable-damper stopper, including the diameter of the steel cable and damping coefficient of the damper. Finally, finite element models were built and time history analyses were conducted to verify the proposed optimization approach. Firstly, the finite element models were proved valid through the comparison between the results of the simulations and the experiments. Then, based on the results of the simulations, the theoretical procedure was validated. The results revealed that the proposed cable-damper stopper reduced the seismic responses of displacements of the top floor and the boiler significantly, about 30.18% and 60.01% respectively compared with their counterparts of CFTPPs without stoppers.

ABSTRACT The implementation of fluid viscous dampers has been proven as a feasible method to improve the seismic performance of buildings. However, the different variables involved in the damper’s design affect the structural response, especially in terms of seismic demand on non-structural elements. This paper presents a parametric study on the floor acceleration response of three case study buildings equipped with fluid viscous dampers through nonlinear time-history analysis. The results show that the different design parameters of fluid viscous dampers significantly modify the floor acceleration response, with some damper configurations yielding floor accelerations larger than those of the buildings without dampers.

ABSTRACT The research investigates the validity of the complete quadratic combination (CQC) method. A new approach is proposed in order to consider the effect of modal correlation more accurately than the CQC method. Statistical analysis indicates that the error in the estimation of modal correlation could be reduced compared to the CQC method. This method is especially more accurate in higher frequency ratios where the role of interaction between modes in the seismic response is noticeable. Statistical analysis reveals that the proposed method is more precise, especially for far-field records. Meanwhile, the proposed method is not sensitive to different site classes.

ABSTRACT Generally, soil–structure interaction (SSI) effects significantly impact the dynamic behavior of fluid storage containers. Hence, ignoring the SSI may result in unrealistic fallouts. This research employs fully coupled numerical modeling to examine this effect on the dynamic behavior of rectangular incompletely filled rigid water storage containers under earthquake excitation. The tanks’ performance is analysed using the coupled Eulerian–Lagrangian (CEL) technique of the Finite Element Method (FEM). The fluid–structure interaction (FSI) behavior of the tanks is studied using the CEL approach, which is formulated in a nonlinear wave theory. The direct procedure using the infinite element is exerted to model soil field, reflect the effects of base flexibility on the tanks’ performance, and investigate SSI influences on tanks’ seismic performance. The impact of base flexibility on the system’s dynamic behavior is studied by paralleling the outcomes of six soil media. The conclusions are provided as surface sloshing heights and the development of maximum compressive stresses obtained from six earthquake excitations for the two aspect ratios and various base statuses. The sloshing response seems to be linked to the tank’s geometrical parameters and earthquake characteristics and is practically independent of differences in the base type. From these analyses, it may be concluded that the SSI influences on impulsive response are dissimilar in broad and tall structures because of the ability of shallow tanks to dissipate more energy through radiation damping rather than tall tanks. Moreover, for the case of medium containers, notable attention would be required to be dedicated to the design of flexible foundations expected to experience near-field earthquake shakings.

ABSTRACT In the present study, an effective analysis framework is developed for generating the floor response spectra (FRS) of nuclear power plants based on the explicit time-domain method (ETDM), an efficient approach recently proposed for nonstationary random vibration analysis of large-scale complex structures. The FRS obtained by the present approach are fully consistent with the code-specified ground response spectra (GRS), and the problems encountered in the traditional time-history method and direct spectra-to-spectra method can be completely avoided. The FRS of a real nuclear power plant are generated to demonstrate the feasibility of the proposed method to engineering practice.

ABSTRACT An updated strong-motion database of the Iranian earthquakes has been used to propose empirical equations for the prediction of peak ground velocity (PGV), peak ground acceleration (PGA), and 5%-damped Spectral Accelerations (SA) up to0.0 s for geometric mean of horizontal components. Some records from the NGA-West2 are added to the database to enrich it at near source distances for large magnitude events. Lack of data in the near source distances causes less accuracy in previous Iranian Ground Motion Models (GMMs) in comparison with the current study. In this work, the regression analyses have been performed on a truncated database which causes to obtain unbiased results. We used 3015 acceleration time series from 594 earthquakes after truncation of data to develop a new GMM. The provided model is valid for Joyner-Boore distances ranging from 0 km to80 km and magnitudes ranging from 4 to 7.9 and Vs30 ranging from50 m/s to500 m/s.