Vertical irregularity is one of the major causes of the failure of the structure. Buildings with vertical irregularities are widespread and unavoidable during rapid urbanization in almost all countries. The safety of such buildings is most important against vulnerability in an earthquake. The vulnerability of structures is assessed using the damage indices of fragility curves. These fragility curves were developed using the HAZUS method, which is used to find the probability of structural damage due to various seismic excitations. This fragility curve determines the probability of none, slight, moderate, extensive, and complete damage to the structures. These fragility curves help to identify the vulnerability percentage of vertical irregularities compared to the regular building. Research also reveals that the vulnerability of the irregular building is similar to the vulnerability identified in terms of roof displacement, base shear, and drift ratio using the THA method. This research also helps to determine the possibility of damage being observed for the structures carrying stiffness and mass irregularities. It is found that stiffness irregularity is more vulnerable than mass irregularity. An increment in collapse probability is observed in stiffness and mass irregularity on the ground floor. Considerable slight to moderate damage possibility is observed in mass irregularity models, and collapse possibility is observed high in stiffness irregularity models. Also, it is observed that the SSI affects adversely on the structures.

Earthquakes are one of the natural occurrences that can lead to massive disasters, either on structures or infrastructure. The seismic response and performance of underground infrastructure such as tunnels against earthquake vibrations is predictably severe due to the complex interaction between tunnels and the surrounding soil, especially one embedded in poor soil material properties. In view of this, previous experiences of tunnel damages subjected to earthquake loads have been reported in the literature. Thus, rigorous analysis is necessary to provide indepth knowledge and understanding of the seismic response of tunnels which beneficial to engineering practitioners in especially in early design stage in order to avoid the future risk of tunnel damage and failure during an unpredictable earthquake event. The aim of this study is to investigate the effect of overburden depth on seismic response of tunnels using the simplified pseudo-static analysis, while simultaneously to emphasize the shortcoming of conventional closed-form solution. This study presents a two-dimensional (2D) simplified pseudo-static analysis of soil-tunnel model embeded at 10m and 20m overburden depth subjected to increasing levels of seismic intensity at the transverse direction of tunnel axis. The numerical investigation was performed using the finite element program PLAXIS 2D. The circular shaped tunnel lining are assumed to be elastic, while the soil is considered as homogeneous, and isotropic in plane strain condition. Considering the complex soil-tunnel interaction, the tunnel lining and soil interface is assumed as no-slip condition. The numerical result of pseudo-static analyses were compared with the conventional closed-form Wang's analytical solution to verify the reliability of the obtained results. The results denoted that the tunnel embedded at 10 m overburden depth experienced considerable seismic-induced deformation and structural forces than tunnel buried at 20 m depth. The deformation and seismic induced structural forces of tunnel increased with increment on the magnitude of earthquake loadings. Thus, it can be concluded that the shallow tunnel suffered more damages compared to the tunnel embedded at deeper depth. Overburden depth of tunnel plays a significant role in modifying the seismic response of tunnel apart of the imposed magnitude of earthquake loadings. The conventional closed-form analytical method tends to overestimate the seismic response of tunnel compared to numerical pseudo-static analysis.

The occurrence of earthquake events has caused numerous causalities and economic losses within the construction industry in the past and present years. However, people have insufficient knowledge and awareness of the impact of earthquakes, especially in understanding the seismic response of complex underground construction industries such as tunneling. Careful consideration of the impact of earthquakes on such structures is crucial due to previous experiences of catastrophic earthquake events that severely damaged underground structures. This study aims to investigate the effect of different soil material properties ( i.e., soft soil and rock) on the seismic response of circular tunnels under increasing earthquake ground motion using simplified pseudo-static analysis, while simultaneously emphasizing the shortcomings of conventional closed-form solutions. To achieve this, a two-dimensional (2D) simplified pseudo-static analysis of a soil-tunnel model embedded at 20m depth was investigated under increasing levels of seismic intensity at the transverse direction of the tunnel axis using PLAXIS 2D software. The tunnel is modeled as a circular shape with a 0.5m thick tunnel lining embedded at a depth of 20 m from the ground surface in two different types of soil profiles i.e. soft soil and rock. The soil is treated as a single-phase medium without excess pore pressure. The six seismic intensities of peak ground acceleration (PGA) ranging from 0.1g to 0.6g were considered in this study. For validation purposes, the numerical results of pseudo-static analyses were verified with the analytical closed-form solution using Wangs' method 1993. The findings indicate that the tunnel embedded in soft soil experienced maximum structural forces for bending moments and axial forces compared to rock. Results denoted that the seismic responses of the tunnel increased with the increment of earthquake magnitude and its epicenter. Notably, the results of analytical methods seemed to be underestimated compared to numerical analyses.

The semi-underground double-storey squat silo (SUDSSS) is a new type of silo with the advantages of preserving grain quality. In this paper, a numerical model of SUDSSS was constructed using solid elements. The proposed numerical model was validated by test results of an experimental underground silo, and the results demonstrated that: (1) Before and after backfilling, the radial and circumferential stress of the underground storey reached their maximum at 2/3 from the bottom and 2/3 from the ground surface, respectively; (2) As the height of grain storage increases, the silo wall stress in the overground storey increases. From the top of the underground storey up to 1/4 height of the overground storey, the stress of silo wall increases. (3) For the underground storey, the maximum stress occurs at 1/3 of the way from the apex of bottom cone.Practical applicationsThe semi-underground double-storey squat silo is a new grain storage device proposed by this paper, which consists of two layers. The lower layer is located in the ground and can utilize the shallow ground temperature to realize the green and low-temperature storage of grain, the upper layer is conducive to the turnover of grain, which can ensure the quality of grain storage. The new silo has the advantages of saving land, energy saving and carbon reduction. Based on the silo, this paper investigates the stress-strain properties of the silo before and after soil backfilling during the construction stage, and obtains the change pattern of the static mechanical properties of the silo. This paper analyses the mechanical properties of semi-underground double-storey squat silo under different storage conditions at the grain storage stage, and studies the change patterns of the mechanical properties of the silo body under different storage heights. Based on SUDSSS, a new type of silo, the mechanical properties of the silo in the construction and grain storage stages were investigated, and the changing patterns of the mechanical properties in these two stages were obtained, which can provide a reference for the engineering design and construction of SUDSSS. image

Engineers are tasked with the challenging task of evaluating the performance and analyzing the risk of systems in the context of performance-based seismic design. All sources of random uncertainty must be taken into account during the design phase in order to complete this assignment. The performance limit states for a structure must be defined using appropriate procedures that take into consideration the system characteristics describing the structure, the soil, and the loads applied to the structural reactions. The main objective of this study is to conduct an in-depth analysis, both linear and non-linear (Pushover), of seismic vulnerability for a reinforced concrete (RC) structure. This aims to probabilistically evaluate the effectiveness of composite materials, particularly those reinforced with glass and carbon fibers, in reducing seismic risk when used to reinforce structural columns. The outcomes of this study will provide valuable insights into the efficacy of FRP reinforcements in enhancing seismic resistance, regardless of the analytical approach adopted (linear or non-linear). They reveal a seismic risk reduction of 48 % for structures equipped with glass fiber-reinforced columns and 67 % for those with carbon fiber-reinforced columns.

This study analyzes the progression, utilization, and inherent challenges of traditional non-linear static procedures (NSPs) such as the capacity spectrum method, the displacement coefficient method, and the N2 method for evaluating seismic performance in structures. These methods, along with advanced versions such as multi-mode, modal, adaptive, and energy-based pushover analysis, help determine seismic demands, enriching our grasp on structural behaviors and guiding design choices. While these methods have improved accuracy by considering major vibration modes, they often fall short in addressing intricate aspects such as bidirectional responses, torsional effects, soil-structure interplay, and variations in displacement coefficients. Nevertheless, NSPs offer a more comprehensive and detailed analysis compared to rapid visual screening methods, providing a deeper understanding of potential vulnerabilities and more accurate predictions of structural performance. Their efficiency and reduced computational demands, compared to the comprehensive nonlinear response history analysis (NLRHA), make NSPs a favored tool for engineers aiming for swift seismic performance checks. Their accuracy and application become crucial when gauging seismic risks and potential damage across multiple structures. This paper underscores the ongoing refinements to these methods, reflecting the sustained attention they receive from both industry professionals and researchers.

This paper employs a three-dimensional nonlinear finite element method to analyze settlement and deformation during construction. By considering the interaction between the superstructure, foundation, and subgrade, the method reveals both the magnitude of settlement and the distribution of uneven settlement across the structure. This information is used to adjust the foundation design or implement structural measures to ensure uniform settlement, thereby preventing damage caused by differential settlement. In terms of absolute settlement values, the Mohr-Coulomb model predicts the largest settlement, with a maximum value of approximately 11.7 cm. The linear elastic model calculates the smallest settlement, with a maximum value of around 4.5 cm. The Duncan-Chang model offers an intermediate prediction, with a maximum settlement value of about 8.9 cm. Utilizing the ABAQUS finite element software, a 3D model of a natural foundation strip for a three-story masonry structure was developed. The Duncan-Chang nonlinear elasticity model, which effectively describes the behavior of hardening soil, was applied within the software platform to conduct a detailed numerical simulation. At the same time, the paper assumes that the foundation soil is considered the linear elastic model and the Moore-Coulomb ideal elastic-plastic model is compared with the internal force of the superstructure under different foundation models obtained. According to the maximum principal stress analysis, the areas where the wall may be damaged are received, and the measures to reduce the uneven settlement are proposed.