Abstract
Structures are typically designed for single seismic events, whereas real earthquakes often consist of multiple tremors, including foreshocks, mainshock, and aftershocks. Many buildings in seismic regions exhibit vertical stiffness irregularity, making this issue particularly critical. A six-story steel moment-resisting frame was designed as the Base Model, and variations in stiffness distributions were created to study pounding effects when placed adjacent to a heavier structure (Adjacent Model). The investigation considered repeated earthquakes (mainaftershock sequences) at two seismic risk levels. The results reveal that the seismic separation gap is the primary factor governing pounding risk, while stiffness distribution and cumulative damage are significant contributing factors. Code-based separation gaps prove generally conservative and sufficient to prevent pounding. However, structures with reduced stiffness in upper stories demonstrate particular vulnerability and require special consideration. Consequently, gap sizing should be case-specific and account for repeated seismic events through practical assessment methods. Furthermore, while structural pounding sharply amplifies peak relative floor accelerations, seismic force demand, maximum inter-story drift ratio, and residual displacement are governed primarily by lateral stiffness distribution rather than by pounding effects. These findings underscore the necessity of incorporating both multiple seismic events and vertical stiffness irregularities in seismic design practice to effectively mitigate pounding risks.
Abstract
Piping systems are crucial components in both industry and society. Earthquakes can damage these systems through low-cycle fatigue or excessive displacement caused by large cyclic loads. Such damage can lead to gas and water leaks, resulting in fires, explosions, and flooding. Therefore, piping systems must be designed to withstand earthquakes, necessitating the use of seismic separation joints or devices. One effective countermeasure against earthquakes is the bellows expansion joint, which is a type of seismic separation joint. In this study, a 3-ply bellow expansion joint was developed to respond to earthquakes. The displacement-load curve was assessed using compression-tensile and bending cyclic loading tests to evaluate the seismic performance and limit state of the developed 3-ply bellows expansion joint. In the compression-tensile cyclic load test, leakage occurred at a displacement of 57.680 mm after 33 repetitions. In the cyclic bending load test, leakage was observed at a displacement of 132.070 mm after 36 repetitions. Additionally, a simplified numerical model for the 3-ply bellow expansion joints was constructed based on the experimental result. The model coincides well with the cyclic loading test results of the 3-ply bellows expansion joint, achieving fitness values of 85.29% for compression–tensile loading and 79.02% for bending. Consequently, the numerical model can be effectively used to understand and design the behavior characteristics of 3-ply bellows expansion joints.
Key Words
3-ply bellows expansion joint; cyclic loading test; piping system; seismic performance; simplified numerical model
Address
Dongchang Kim: School of Convergence & Fusion System Engineering, Kyungpook National University, 80 Daehak-ro, Daegu, 41566, Republic of Korea
Bub-Gyu Jeon: Seismic Research and Test Center, Pusan National University, 49 Busandaehak-ro, Yangsan, 50612, Republic of Korea
Young-Soo Jeong: Seismic Research and Test Center, Pusan National University, 49 Busandaehak-ro, Yangsan, 50612, Republic of Korea
Jinseok Yu: Taesung Flexible Co., 180 Gomo-ro, Gimhae-si,50875, Republic of Korea
Seunghyun Eem: School of Convergence & Fusion System Engineering, Kyungpook National University, 80 Daehak-ro, Daegu, 41566, Republic of Korea
Abstract
Beam-to-column seismic moment connections play an important role in the stability of structures during events such as earthquakes or progressive collapse. A key strategy for preventing brittle fractures in these connections is the use of seismic fuses, such as the reduced beam section connection (RBS). While investigating the progressive collapse strength of these connections has been a demanding subject for many years, few studies have been performed on the post-earthquake progressive collapse behaviors of these connections. Therefore, this study investigates the behavior of steel moment frame structures with RBS connections against post-earthquake collapse. To evaluate, 17 structures with rigid and RBS connections are considered, in compliance with seismic design principles, the number of floors, behavior factors, and different seismicity levels. Following the application of 11 records with varying specifications, the behavior of structures subjected to column removal is analyzed. The evaluation of the structure's behavior is based on the nodal vertical displacement of the removed column and the ductility demand of the connections. The structures with RBS connections show a maximum performance level of IO-LS in the plastic hinges, meeting the acceptance criteria of regulations, despite the higher demands. In the seismic design of structures, the type of connection, seismicity of the area, and ductility level of the moment frame play a crucial role in enhancing resistance against post-earthquake progressive collapse. Implementing ductile detailing, like a special moment frame with RBS connections in high seismicity areas, activates the highest robustness of structures in post-earthquake column removal scenarios. However, using precise seismic detailing in structures located in moderate seismicity increased the ductility demands and nodal vertical displacements by up to around 60 and 3.0 times, respectively.
Key Words
column removal scenarios; non-linear dynamic analysis; post-earthquake progressive collapse; RBS connections; seismic connections; steel moment frames
Address
Behzad Rezaee, Payam Tehrani, Behrouz Behnam: Department of Civil and Environmental Engineering, Amirkabir University of Technology, Iran
Abstract
With the high requirements for manufactural precision in high-tech domains, studying the microvibration control for precision instruments is of great importance to the development of high-tech industries. Quasizero stiffness (QZS) isolator, which can provide a high static and low dynamic stiffness, is an effective device to overcome the drawbacks of conventional passive isolator. In this paper, a suspended corrugated pipe quasi-zero stiffness (SCP-QZS) isolator is proposed and the mechanical model is derived. Based on this, a design procedure is summarized and a SCP-QZS isolator is designed and studied by theoretical analysis and dynamic simulation. For the application in micro-vibration control, an isolation platform based on SCP-QZS isolator and air springs is also established and investigated under environmental excitation measured on-site. The results show that the SCP-QZS isolator exhibits a piecewise behavior and a great isolation performance, even under some non-ideal conditions so that it has sufficient robustness. The isolation platform can effectively control the environmental micro-vibration and satisfy the high demands for sensitive instruments.
Address
Zhongyu Zhou: The First Construction Co., Ltd of China Construction Third Engineering Bureau Group, Wuhan, China
Sheng Li: Department of Disaster Mitigation for Structures, Tongji University, Shanghai, China
Zheng Lu: Department of Disaster Mitigation for Structures, Tongji University, Shanghai, China; State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai, China
Lele Shang: The First Construction Co., Ltd of China Construction Third Engineering Bureau Group, Wuhan, China
Yu Chen: The First Construction Co., Ltd of China Construction Third Engineering Bureau Group, Wuhan, China
Abstract
To investigate the influence of adding transverse ribs near the end of the precast ribbed bottom panel on the flexural performance of the concrete composite slab with precast ribbed panel (CSPRP), bending test is conducted on concrete composite slab with precast one-way ribbed panel (SORP) and slab with precast two-way ribbed panel (STRP). The test results indicate that the static performance of the SORP and STRP specimens is similar in terms of cracking load, ultimate bearing capacity, and deflection. Compared with the SORP, the bearing capacity of the STRP is higher when the component enters plasticity from elasticity. The overall performance is better and the crack distributions are more uniform. Numerical simulation is performed with the finite element (FE) analysis software ANSYS and FE results are basically consistent with the experimental results. In addition, comparison of the theoretical values with the test indicates that the formulas proposed are accurate and applicable for calculation of ultimate bearing capacity of the CSPRP.
Address
Panxu Sun, Keguang Li, Xiangcheng Zhang, Dongwei Wang, Shaowei Hu: School of Civil Engineering, Zhengzhou University, Zhengzhou 450001, China
Shuxia Wang: School of Materials Science and Engineering, Zhengzhou University of Aeronautics, Zhengzhou 450046, China
Abstract
Earthquakes are among the most destructive natural disasters, directly threatening the safety of structures.
Accurate estimation of the seismic performance of buildings is critical to minimizing loss of life and property. Major
earthquakes have caused severe damage in recent years, particularly in regions with weak building stock. This study
compared nonlinear analysis methods for reinforced concrete building models with 3, 6, and 9 stories. The structural
analyses were conducted using the SAP2000 finite element software. Each model was subjected to both nonlinear
static pushover analysis and nonlinear time-history analysis. 11 different ground-motion records were used for the time-history analyses. The resulting maximum displacement and plastic hinge distributions were evaluated. In the static pushover analysis, target displacement values recommended by TBEC-2018, ASCE 41-13, ATC-40, FEMA-
356, and FEMA-440 were taken. For each target displacement, the maximum displacement and the number of plastic hinges (categorized as IO, LS, and CP performance levels) were determined separately for beams and columns for each story. These results were compared for each earthquake and for the average of all 11 ground motions. As a result, the study identifies that ASCE 41-13 and ATC-40 provide the most accurate convergence to the time history analysis results for Model 1, while ASCE 41-13 provides it for Model 2, and ATC-40 provides it for Model 3, with less than 2% difference in terms of maximum displacements.
Key Words
reinforced concrete building; static pushover analysis; target displacement; time history analysis
Address
Burak Çakil, Ömer F. Osmanli, Ömer F. Taş, Muhammet Karaton, Ozan İnce, Erkut Sayin: Department of Civil Engineering, Faculty of Engineering, Firat University, Elazig, Turkey
