Advanced Materials Research Vols. 255-260

Abstract: Collapse safety is the most important objective of performance-based seismic design. Buildings should have enough safety margin to avoid collapse during severe or mega earthquake. However, current Chinese seismic design code does not have explicit design specification or quantitative evaluation for collapse-resistant capacity. Take a two-story masonry building as an example, an equivalent frame model for pushover and incremental dynamic analysis are established, and the comparison are also studied. In addition, the fragility curves can also be obtained. The analysis results show that the results of plastic hinge mainly appear in ground floor wall between windows and doors. Moreover, the analysis result has good uniformity with seismic damage. Judging from the failure mechanism, pushover and incremental dynamic analysis have very good similarity. In addition , they show elastic deformation is very small and brittleness is very apparent of the masonry building.Seismic vulnerability analysis shows that the significant damage and the near collapse curves are very close to each other .This mean that , once the significant damage limit state is reached ,only small PGA increments are need for reaching the near collapse limit state.

Abstract: Two 1:4 scale wall specimen was tested under cyclic load to determine its seismic behavior, the responses of the steel frame with GRC lath are studied such as the failure modes, hysteretic behavior, ductility, energy dissipation, and the experimental results were compared with the steel frame. The testing data analysis indicated that bearing capacity, lateral stiffness, ductility and energy dissipation of the steel frame with GRC light hollow lath are superior to the steel moment frame, the steel frame with GRC lath is an ideal lateral resistant system. The prolapse of GRC lath from the frame did not appear, so the steel frame with GRC lath could be better used in the earthquake zone. Due to the collapse of connection of lath with frame, the ductility coefficient of the system is generally between 2 and 3, it is less than requirement of the seismic design specifications, and therefore a suggestion is that the seismic design of steel frame with GRC lath can be according to non-filled wall frame structure.

Abstract: Continuous Beam Bridge was widely used, while seismic problem of it was prominent in meizoseismal area. According to mechanism of DSB, seismic performance of DSB was studied and the parameters of DSB were analyzed later, based on non-navigable bridge of Hong Kong-Zhuhai-Macau Bridge in deep water. It was found that DSB was an effective seismic-isolation device which could significantly reduce the seismic force although seismic displacement of bridge was increased. Yielding force and post-yielding stiffness were two main parameters of DSB.

Abstract: This paper presents a seismic reinforcement approach to a frame structure, which was added from four-storey to six-storey, and is located at degree-8 earthquake intensity zone and type-II site, by using the Friction Damper. Firstly, the dynamic performance of the original structure had been tested and the performance parameters had been gotten, which were used to build up the F.E. model and to check its accuracy. Secondly, the structure simulation analysis was conducted by using the constructed F.E. model. Finally, the seismic strengthening of the frame structure being added to six-story was analyzed and calculated by using Friction Damper. This has effectively improved the structure seismic performance and the seismic performance of the reinforced structure meets well with the seismic code requirements. This approach will be helpful for the structural design engineers and the researchers.

Abstract: Inter-story drift ratio is a general damage index which is being used to detect damaged stories after severe ground motions. Since this general damage index cannot detect damaged elements also the severity of imposed damages on elements, a new real-time seismic damage detection method base on artificial neural networks was proposed to overcome this issue. This approach considers nonlinear behaviour of structures and not only is capable of detecting damaged elements but also can address the severity of imposed damages. Proposed algorithm was applied on a 3-story concrete building .The obtained results confirmed accuracy and robustness of this method.

Abstract: A performance-based seismic design approach for reinforced concrete beam-column joints has been proposed in this paper. Instead of adopting empirical analysis such as in ACI 318M-08 building code, the proposed approach is based on rational analysis of the stress-strain state of the joint. Two limit states are considered in the design: serviceability limit state and life safety limit state. Performances of the joint at these two levels are determined respectively, with due considerations of capacity design philosophy and post-earthquake repair requirements. Then stress/strain analyses of the joint panel using the Mohr circle in conjunction with the softened stress-strain relationship of concrete are adopted simultaneously to design the joint to achieve the predetermined performance level. Effectiveness of proposed method are validated by using the model to interpret the behaviors of joints observed in previous experiments.

Abstract: Control devices can be used in structures to attenuate undesirable vibration on engineering structures. In order to mitigate the response of structures during the earthquakes and high intensity winds semi active control has been widely used. Semi-active control need less energy in compare with active control. So they are more reliable and more effective in mitigating the effects of earthquakes. MR damper are semi active control devices that are managed by sending external voltage supply. The inducing current monitoring of MR dampers are intelligently managed by fuzzy logic control (FLC). Validation of fuzzy logic controller that is optimized by a particle swarm optimization(PSO) is pursued in this study. Finally, optimal fuzzy logic controller is identified and validated through numerical simulation for seismic excitation. In 3-storey benchmark building, results showed that optimized fuzzy logic controller was robust and effective in reduction of both displacement and acceleration responses.

Abstract: The intersection of the transverse traffic tube and main tunnel is the weak link in the tunnel, as its structural forms are changed greatly and stiffness is discontinuous, so it does not help resist the seismic action. Based on the soil-structure interaction model and the use of visco-elastic boundary conditions and of time history analysis method, this paper, in combination with the Menglian tunnel engineering on the Bao-Teng Highway in Yunnan, has made a research of seismic dynamic response in the aforesaid intersection by analyzing its seismic dynamic characteristics and stability upon acquiring its displacement, stress, acceleration of dynamic response and distribution characteristics, and then put forth some disposal measures by seismic reinforcement, which can serve as reference to seism-reducing design of the weak link in the tunnel as well as other similar projects in a highly seismic region.

Abstract: According to the disadvantages of the effects that base isolation was limited to high frequency components of seismic wave, smart base isolation system consisting of rolling isolation bearing and magnetorheological damper was applied to structural vibration control. Based on magnetorheological damper employing a Sigmoid model, a semi-acive fuzzy control strategy suitable for smart base isolation was presented. Simulation analysis was carried out to a two-story steel frame structure employing smart base isolation in the action of different kinds and magnitudes of earthquake wave. The results show that smart base isolation system is reliable and effective, and seismic response can be controlled effectively by semi-active fuzzy strategy.

Abstract: This paper presents an analytic solution for the diffraction of plane P waves by a cylindrical inclusion in half space by Fourier-Bessel wave function expansion method, in which the flat surface of half space is approximated by a large curved surface. The equation can be constructed by the continue boundary and the free surface condition. Based on parametric analysis, the impact of the inclusion on surface displacement amplitude is discussed. It is illustrated that there is large difference of the diffraction characteristics between the hard inclusion and soft inclusion. The displacement response depends strongly on the incident angle and frequency. The diffraction effect can be ignored with large embedded depth of the inclusion.