Seismic isolation is used worldwide to protect a myriad of structures from traditional use to industrial applications. Its success evolves from the use of rigid body motion reducing the demand on the structure especially in terms of drifts. Nonstructural damage refers to the loss of content of a structure including equipment and machinery that can be deemed necessary for facility operation. In many cases, this content is acceleration sensitive especially for machinery with fundamental frequencies above 2 Hz. Most work to date has focused on either nonstructural damage or isolated buildings with little known about the relationship between them. With this in mind, the study herein explores the performance of nonstructural content in seismically isolated structures in the near-fault region with vertical excitation. Using floor level time histories and response spectra, the presence of high frequency content is observed along with areas of decreased performance for the seismic isolation system. The results reinforce the complex relationship between the performance of nonstructural content, seismically isolated structures, and near-fault excitations.

Seismic safety evaluation of weir structure is significant considering the catastrophic economical consequence of operational disruption. In recent years, the seismic probabilistic risk assessment (SPRA) has been issued as a key area of research for the hydraulic system to mitigate and manage the risk. The aim of this paper is to assess the seismic probabilistic risk of weir structures employing the seismic hazard and the structural fragility in Korea. At the first stage, probabilistic seismic hazard analysis (PSHA) approach is performed to extract the hazard curve at the weir site using the seismic and geological data. Thereafter, the seismic fragility that defines the probability of structural collapse is evaluated by using the incremental dynamic analysis (IDA) method in accordance with the four different design limit states as failure identification criteria. Consequently, by combining the seismic hazard and fragility results, the seismic risk curves are developed that contain helpful information for risk management of hydraulic structures. The tensile stress of the mass concrete is found to be more vulnerable than other design criteria. The hazard deaggregation illustrates that moderate size and far source earthquakes are the most likely scenario for the site. In addition, the annual loss curves for two different hazard source models corresponding to design limit states are extracted.

Masonry structures are relatively inexpensive and easier to construct compared to other types of structures such as steel and reinforced concrete buildings. However, they are relatively heavier, less ductile, and more vulnerable to damages in earthquakes. In this research, a new proposed low-cost seismic isolator made of rubber and steel rings (SISR) was used to reduce the seismic vulnerability of masonry walls. Two specimens of the proposed SISR were fabricated (placed on top of each other) and tested for horizontal displacement under a fixed vertical load condition according to ASCE 7-16 loading protocol. The proposed SISRs which out-performed the standard loading protocol of ASCE 7-16 were evaluated in a numerical study of the concrete block walls under Erzincan and Imperial Valley-06 earthquakes. ABAQUS finite element software was used for the structural modeling of the walls. The results showed the proper performance of the proposed SISRs in reducing the acceleration and preventing cracks in the masonry walls.

The friction and viscous damping actions always cause nonlinear responses of a seismic isolation system under earthquakes. Their influence on the seismic responses needs investigation in detail. In order to analyze the effects of nonlinear phenomenon on the seismic isolation system, a mathematical model was built for such a nonlinear isolation system, and the nonlinear responses were calculated and analyzed. The numerical results indicate that an appropriate combination of spring, Coulomb friction and viscous damper is able to achieve an optimal seismic performance. The stiffness and natural period of system are significantly influenced by the friction action. Both the friction action and the viscous damping action can dissipate earthquake energy, and the optimal value of one depends on the value of the other in the seismic isolation system. All of the values of spring, Coulomb friction and viscous damper should be accurately evaluated before the design of seismic isolation system.

Dams are constructed across the river to confine the water and utilize it for various purposes such as hydroelectricity generation, flood control, irrigation, etc. Failure of dams causes huge loss to property and lives. Dams, designed to be built in high seismicity areas, are prone to damage due to intensive earthquake events. Strong ground motions recorded in the vicinity of fault planes are generally considered as near fault (or near source) ground motions. Near fault ground motions possess considerably different features which have high damage potential. In last few decades, a lot of studies have been conducted on the identification, characterization and simulation of pulse-type and non pulse-type ground motions. However, researchers have paid attention to the seismic safety assessment of dams under near fault and far fault ground motions since the last decade. In this context, this present study reports a state-of-the-art review on the seismic behaviour of various types of dams under different ground motions, based on available literature. This study also describes existing modelling techniques of the dam-reservoir-foundation system, failure modes, seismic analysis method and seismic response of different kinds of dams to near fault and far fault earthquakes. Finally, the study attempts to find the research gaps, which should be given proper attention in the future.

Reinforced Concrete (RC) structural wall is widely used in the lateral force resisting system for multistoried RC frame buildings located in earthquake-prone regions. In such buildings, the wall is connected to the RC slab at every floor level. The junction region of shear wall and floor slab constitutes an important link in the load path from slab to wall during earthquake shaking, thereby influencing the pattern of lateral load distribution in the shear wall. In case of multistoried building, the maximum elastic drift is estimated by carrying out linear static analysis for different load combinations as recommended by the Indian Earthquake Code IS 1893 (Part 1): 2016. However, during strong earthquake shaking, the inelastic lateral drift needs to be monitored to avoid undesirable levels of damage in structural members. The inelastic drift level of an isolated slender shear wall considering the behaviour of wall-slab junction has not been studied in the past. The present study aims to investigate the possible lateral drift limit of RC wall frame building considering the effect of floor slabs.

The seismic performance of a steel frame base-isolated structure with steel spiral spring limiters is experimentally investigated under near-fault ground motions. A series of shake table simulator tests are carried out to analyze the dynamic response of isolation layer and superstructure. The test setup consists of a one-eighth scale five-story steel frame with steel spiral spring limiters that are designed and modeled in different parameters and stiffness, as well as various reserved gap sizes between the testing structure and limiters. The main output parameters are the maximum deformation at the isolation level, the maximum vertical force of isolation bearings, and inter-story drift. The results further reveal the seismic impact on the isolation layer and superstructure dynamic response caused by the limiter stiffness and reserved gap size.

This paper presents a mainshock-aftershock seismic fragility and collapse capacity assessment of reinforced concrete (RC) structures retrofitted with a hybrid damper composed of a steel slit plate and friction pads. Three and eight-story RC buildings are designed and assessed before and after retrofit considering the aftershocks effect. Non-linear time-history response analysis (NLTHA) using twelve natural earthquake sequences are used to produce incremental dynamic analysis (IDA) curves to obtain the median collapse capacity of the structures. Three different damage state (DS) levels are used for the mainshock ground excitation to quantify the scale factors required for conducting the aftershock IDAs. The maximum inter-story drift ratio (MIDR) is used as the main engineering demand parameter. The study shows the importance of considering the aftershock in the seismic assessment process of RC structures. The un-retrofitted structures are found to experience a high level of deterioration under aftershock event which is not considered in the design stage. The findings of the study reveal that the mainshock-aftershock sequence responses of the retrofitted structures show better performance in terms of the median collapse capacity and the seismic fragility compared to the un-retrofitted ones.

Shear wave velocity (Vs) profile is one of the critical geotechnical measurements of soil layers for seismic hazard assessment and liquefaction potential evaluation. Enhancing the effectiveness of in-situ Vs profiling by reducing time and cost is of great interest. For that reason, this study aims at assessing Vs profile generation from a single-station three-component geophone with additional borehole log data for constraining parameter space. Based on multichannel analysis of surface waves (MASW), and microtremor array Measurements (MAM) conducted previously at seven sites located in Bukit Timah Granite, Singapore, this study utilized HVSR signals for Rayleigh wave ellipticity (ellipticity curve) inversion with additional inversion constraint using borehole log data. The resulting Vs profiles and reference Vs profiles from MASW and MAM were quantitatively compared using average Vs of 30 m (Vs30). The profiles generated from ellipticity curve inversion revealed a good agreement with Vs reference profiles. Vs30 based site classification results also indicated a good fit of two test results. Therefore, HVSR measurements for further ellipticity curve inversion, with already available borehole log data for constraint, is considered as a promising cost and time-effective site classification approach.

Precast reinforced concrete (RC) frames have been rapidly developed in structural engineering due to their various advantages, such as high efficiency and low environmental pollution. However, the construction quality of precast RC frames is difficult to guarantee, and the interface of new and old concrete and the bond-slip effects of additional steel bars may lead to different performance levels of precast RC frames. Therefore, it is necessary and important to investigate and assess the seismic performance of precast RC frames that adopt the conformation of Chinese code. In this paper, a numerical simulation method for precast RC frames is developed based on OpenSEES software, in which the Joint2D element is used to simulate the beam-to-column connections to consider the shear and bond-slip effects. Two prototype structures of precast RC frames are designed, and the nonlinear time history analysis is performed to explore the seismic performance of the precast RC frames according to the Chinese code. Meanwhile, the incremental dynamic analysis and fragility analysis are conducted to study the differences in seismic performance and collapse resistance between precast RC frames and cast-in-situ RC frames.