Applied Mechanics and Materials Vols. 501-504

Abstract: Taking Magunyan landslide located in Beichuan County as a typical example, the stability influence factors of bedding slopes under the action of seismic load were analyze by using the ANSYS software in this study. The influence factors include excavation, interlayer cohesion and friction coefficient, earthquake magnitude and vibration direction. The related analysis showed that significant influences of excavation existed on the deformation and failure of slopes. And the bedding slopes stability increasing with the interlayer cohesive, the interlayer friction coefficient and earthquake magnitude increases. The analysis also showed that horizontal vibration is the most detrimental on the stability of slopes.

Abstract: In this paper, the influence of topography on ground-motion intensity parameter, response spectrum, peak ground acceleration (PGA) and the ratio of response spectrum were studied based on the measured data from large scale shaking table test and observation stations in XiShan park for Wenchuan earthquake. The results show that: in the EW direction, the height do not affect PGD, SMA, VSI and HI, while V_RMS decreases slightly at the middle of the slope, the other intensity parameters increase with the increase of height. In the EW direction, the height has no influence on PGD, V_RMS, SMA, SED, A_RMS, VSI and HI, while other parameters increase as the height increase. In the UD direction, the height has no influence on SMV, PGD, V_RMS, SMV, ASI, VSI and HI, while A_RMS decreases at the middle of the slope, and the other intensity parameters increase as the height increase. Ignoring the local topographic effect, the amplitude of response spectrum increases with the increase of height at the part of short period (T1s), the part of long period (T>1s) is not effected by height. The ground motion will be amplified by local canyon topography, and the influence of local topography is larger than height. The research carried out in paper will deepen the understanding of topographic effect. 0 Preface Earthquake often cause extensive rock slope failures and various types of mass movement in mountainous areas. Catastrophic seismically-induced landsides are among the Earths most powerful geomorphic events, causing sudden and dramatic changes to the landscape, creating high risks to both infrastructures and life, and reputedly causing large economic losses. Seismic waves interacting with topography lead to amplification and deamplification of resulting ground motion. In the western mountainous areas of China, the topography is extremely complex, many large hydropower stations were built in narrow valleys and many large bridge piers were built on valleys and hillsides, so the research about topographic effect is essential to the seismic design of large-scale projects. Topographic effect is always analyzed with following three approaches: motion observation, analytical analysis and numerical analysis. The motion observation is regarded as the most efficient and common approach [1]. Long time ago, the researchers found that the intensity of buildings built on local convex topography was abnormal, in order to reveal the reason of abnormal intensity, array stations were constructed specially to study the effect of local convex topography on ground motion, some observation data were obtained. Some L-7 type strong motion seismographs were installed at the crest and foot of Kagel and Josephine mountain, California, by Lawrence L. Davis and Lewis R. West, the 2 array stations had recorded several aftershocks record of SanFernando earthquake, which occurred on February 9, 1971[. Some L-7 type strong motion seismographs were also installed at the crest, hillside and foot of Butler mountain, Nevada, to record blasting vibration in test site. In 1984, in order to observe the topographic effect of rocky mountain, 8 observation stations were installed by B. E. Tucker, five stations were placed in two tunnels with different elevation, the other three were placed at the surface of outcropped rock [. After the 1989 Loma prieta earthquake, dense array stations of seven digital and triaxial seismographs were mounted on Robinwood Ridge, which is located at 7.3km northwest of epicenter, to analyze the reason of seriously damage on high-strength buildings and cracks of ground [4,. In China, a earthquake observation station was constructed in XiShan Park, ZiGong, SiChuan province in 2007, which recorded the main acceleration time history of WenChuan earthquake perfectly, the establishment of this station offers valuable data to researchers for exploring the local topographic effect on ground motion [6]. In 2010, a research was conducted by Wang Haiyun and Xie Lili with traditional spectral ratio method, some significant conclusions were drawn about the influence of topographic effect on ground motion [7]. In this paper, WenChuan seismic wave was analyzed in time and frequency domain to explore the influence of topography on ground-motion intensity parameters, response spectrum and spectrum characteristic.

Abstract: It is common for using light steel structure as an upper layer to alter the multi-layer frame structure. But it is easy to form vertical irregular structure of rigid upper and flexible bottom. And the mass, stiffness, period and damping ratio are change after layer-adding. So it should take a holistic analysis of the structure. By using sap2000 to simulate a two-layer steel frame with a portal frame added, the seismic performance was analyzed. The result shows: transfer floor was relatively weak, it requires attention when seismic design; damping ratio has a great influence to seismic, it should been chose reasonably.

Abstract: The pseudo-static tests were carried out on seven steel reinforced recycled concrete columns. The main parameters of specimens were recycled aggregate replacement ratio, axial compression ratio and volumetric stirrup ratio. The results indicate that the incorporation of recycled aggregate doesnt reduce the horizontal bearing capacity, ductility and the energy dissipation capacity of specimens and has little effect on seismic performance. The seismic performance of steel reinforced recycled concrete column decreases significantly in the high axial compression ratio. The ductility, horizontal bearing capacity and the energy dissipation capacity of the steel reinforced recycled concrete column increase with a rise in the volumetric stirrup ratio. This study provides a reference on the application of the steel reinforced recycled concrete column.

Abstract: The seismic response of space structures has been widely studied in the past few years. It has been shown that space structures behave well under seismic loading. However there has been little attention given to the effects of geometrical non-linearity on the seismic response. In this paper, a double-layer truss model was created by finite element analysis program-Lusas. The analysis process took into account of geometrical non-linearity and a 3D seismic loading obtained from a real earthquake. Time-history method was used to investigate the axial forces and displacements of critical members of the model during the earthquake. The seismic behavior of the model and the effect of non-linearity were finally discussed for further applications and studies.

Abstract: This experimental program was designed for investigating the seismic behaviors and strengthening effect of pre-damaged RC frame columns retrofitted with sprayed BFRP and hybrid BF/CFRP. Four RC frame column specimens, among which one was unstrengthened and three was pre-damaged and strengthened with sprayed FRP, were tested under an incremental loading procedure of the pseudo-static, cyclic shear loads combined with constant gravity loads. The test results including the failure mode, ultimate bearing load capacity, load-displacement hysteresis curves and ductility of specimens were obtained and analyzed. It indicates that spraying hybrid BF/CFRP strengthening scheme can effectively improve the ductility and energy dissipation ability of pre-damaged concrete frame columns. Although the improvement of the peak loads and ultimate lateral deformation of damaged frame columns were not obvious compared with those of the reference column, but it should be pointed out that the strengthened columns were pre-damaged seriously with yielded steel bars and the recover of load bearing ability resulted from spraying FRP retrofit can not be neglected. It also shows that increasing the thickness of spraying overcoat can effectively improve the energy dissipation ability of damaged frame columns.

Abstract: Frame structure with infill-walls has been widely used in China, Many domestic experts and scholars have done a great deal studies on the seismic behavior of infilled frames and theorizes that the infill-walls greatly influences the frame structure on seismic behavior. In this paper, summarized the seismic performance of infilled frames from three aspects: the arrangement and structure of infill walls and their connection with frame beam-column.

Abstract: Multi-scale elastoplastic dynamic analysis of the welded connections is conducted under the strong earthquake excitation based on a steel frame engineering case. Two types of multi-scale model are built for the contrastive analysis, and the plastic deformation of the connection section is extracted to investigate the application of the plane-section assumption. The results indicate that elastic-plastic status makes the column and beam sections not meet the flat section assumption. Finally, the determination method of the refined modeling zone is studied based on the application of the plane-section assumption.

Abstract: 3 medium thick-walled cold-formed steel top-and-seat angle joints were designed. The ABAQUS nonlinear finite element analysis on earthquake resistance behaviors of the joints were conducted under low cyclic loading. The results indicate that the failure processes and failure modes of 3 specimens are basically the same, the destruction of joints derive from buckling deformation of the top-and-seat angle and buckling of the steel beam flanges; the shapes of hysteresis curves of all specimens are obvious pinch together and present spindle, the displacement ductility factors are greater than 5.5, the equivalent viscous damping factors are greater than 0.158, all the specimens possess good energy dissipation capacity. The secant stiffness variations are almost similar, each specimen represents significant degradation. Increase the thickness of angle and diameter of high-strength bolt can improve the mechanical performance of the joints. Increase the bolt diameter, the ductility, energy dissipation capacity and initial stiffness enhance obviously, however, there is no apparent effect while increasing the thickness of angle.

Abstract: Shear wall systems are the most commonly used lateral load resisting systems in high seismic zones because they provide significant lateral strength, stiffness, and deformation capacity. The work further investigates the seismic performance of different kinds of shear walls. Classified and brief comments about the seismic performance and the exist drawback of different kinds of shear walls and its application are conducted. Lastly, some useful suggestions and a new structure are proposed for the further research.