Entity

Time filter

Source Type


Chen Z.Y.,Tongji University | Chen Z.Y.,Shanghai Key Laboratory of Engineering Structure Safety | Chen W.,Tongji University | Zhang W.,Shanghai JiaoTong University | Lou M.L.,State Key Laboratory of Disaster Reduction in Civil Engineering
International Journal of Computational Methods | Year: 2016

High axial force in central columns induced by strong vertical earthquake component is one of the most important factors in failure of subway stations. In this paper, the pushover method is adopted to simulate nonlinear behaviors of a multi-story subway station in Shanghai with different axial compression ratios through the general purpose finite element code ABAQUS. To simulate concrete material degradation during an earthquake accurately, the concrete damaged plasticity model was selected to trace damage characteristics of central columns. The softening index was used to describe the damage of the overall structure. Numerical results showed that in the structure level, the increase of axial compression ratio leads to the remarkable decrease of the structure ductility. The value of the softening index become less, which implies that the range and magnitude of damage to the structure become less either. However it should be noted that damages may be concentrated on certain members of the structure, such as central columns which are commonly considered to be the weakest but most critical part of an underground structure. In the member level, numerical results also showed that the increase of axial compression ratio led to small eccentric compression failure of central columns and accelerated the development of their compression damage. © 2016 World Scientific Publishing Company.


Shi Y.,Tianjin University | Xiong W.,Tianjin University | Li Z.-X.,Tianjin University | Xu Q.,Shanghai Key Laboratory of Engineering Structure Safety
International Journal of Impact Engineering | Year: 2016

Most casualties and injuries resulting from a terrorist attack are caused by the fragments discharging from the failure structural components or building envelope systems. Unreinforced masonry wall, which is widely constructed as structural components or building envelope worldwide, tends to break into sharp fragments under terrorist explosions, especially when explosions are in the close range. Therefore, it is of great significance to study the local damage and fragments of unreinforced masonry walls under close-in explosions. In this paper, two unreinforced masonry walls were tested under blast loads generated by 1kg and 6kg of TNT charge separately to investigate their failure mechanism and fragment characteristics. The local damage such as spalling or punching damage of the masonry wall with fragments in different sizes and splash distances were observed, and the splashed fragments were categorized and weighted. The fragment size distribution was also analyzed and it was found that the size distribution of the fine portion of the fragments followed a Weibull distribution. © 2015 Elsevier Ltd. All rights reserved.


Han C.,Nanjing Southeast University | Xu Q.,Shanghai Key Laboratory of Engineering Structure Safety | Xu Q.,Shanghai Research Institute of Building Sciences | Liu Q.,China Railway Siyuan Survey and Design Group Co. | And 2 more authors.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2015

To investigate the fire endurance and resistance of RC continuous T-beams under ISO 834, four specimens at different load levels were experimentally studied and analyzed using FEM. It shows that the control specimen and the exposed specimens all collapsed with the flexural failure mode, but the sequence of plastic hinge development are opposite. The fire endurances of specimens were 160, 99 and 58 min respectively when the load levels were 30%, 50% and 70% of the ultimate load. It is found that the fire endurance of RC continuous T-beams exposed to fire decreases gradually when the load level is increased. The residual mid-span displacement of RC continuous T-beams after fire increases when the load level is increased. Test results show that the distribution of temperature field of the flange plate is similar to the one-side exposed RC slab, and the distribution of temperature field of the web is similar to three-side exposed RC rectangular beams. It is the main cause of the redistribution of internal force that the stiffness of the cross-section of RC continuous T-beam is decreased in the process of the fire. FEA was also conducted and its predictions of the fire endurance, the temperature field and the failure process are all in good agreement with the test results. ©, 2015, Science Press. All right reserved.


Xie Q.-F.,Xian University of Architecture and Technology | Du B.,Xian University of Architecture and Technology | Zhang F.-L.,Shaanxi Institute of Architecture Science | Zheng P.-J.,Xian University of Architecture and Technology | Xu Q.-F.,Shanghai Key Laboratory of Engineering Structure Safety
Gongcheng Lixue/Engineering Mechanics | Year: 2014

Based on the analysis on the force mechanism of dovetail joints, their rotational moment was analyzed and a moment-rotation calculation formula was deduced. The existed test approved that the formula is accurate and the calculated result agrees well with the test result. According to the moment-rotation calculation formula, the factors affecting the rotational stiffness of dovetail joints were analyzed. The results show that: the rotational moment and initial rotational stiffness are increased as the increase of friction coefficients; the increase amplitude of initial rotational stiffness is reduced when the friction coefficient is more than 0.5; the rotational moment and initial rotational stiffness are improved with the increase of the length and angle of a tenon; the rofational moment is improved with the increase of the height of a tenon, but the initial rotational stiffness very little. The conclusions could provide a theoretical basis for the mechanics analysis of ancient timber structure buildings. ©, 2014, Tsinghua University. All right reserved.


Xie Q.,Xian University of Architecture and Technology | Xie Q.,Shanghai Key Laboratory of Engineering Structure Safety | Du B.,Xian University of Architecture and Technology | Xiang W.,Xian University of Architecture and Technology | And 3 more authors.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2015

In order to investigate the seismic performance of the mortise-tenon joints, considering the influences of vertical load, Pubofang, sparrowbrace and size effect, the low-cycle reversed loading tests were carried out. Seven mortise-tenon joints were made as the fabrications methods of Song Dynasty. The seismic behavior and their change laws, such as failure patterns, hysteretic behavior, bearing capacity, degeneration of stiffness and energy dissipation, were compared and analyzed. The results show that the failure patterns are mainly partial evulsion of tenon and extrusion deformation of mortise and tenon, and the beams and columns are intact. The tenon slips longitudinally along the length of the column without vertical load; under the influence of Pubofang, the evulsion of the tenon is smaller and shear deformation occurs on the edge of the connection between Pubofang and Mantou mortise. As the rotation rises, the sparrow brace separates from the beam gradually. The hysteretic loops are Z type, and have obvious gathering effect. The hysteretic loops become fuller when the vertical load increases. The hysteretic loops of the joint with Pubofang is smoother and the symmetry is better, while the loops with sparrow brace shows evident asymmetry. With the increase of the vertical load, the opposite bearing capacity is higher, but the forward bearing capacity is lower. Pubofang increases the bearing capacity dramatically in both directions, while the sparrow brace only works in the forward. The rigidity of the joint with Pubofang improves greatly, but the energy dissipating capacity becomes weaker. The sparrow brace improves the energy dissipating capacity just in the primary stage. The bearing capacity and rigidity of the joints are all against the similarity relationship, and the theory basis could be provided according to the fitted formulas. ©, 2015, Science Press. All right reserved.

Discover hidden collaborations