Advanced Materials Research Vols. 919-921

Abstract: Rammed earth structures are widely used as farmers dwellings in the southwest of China, however, they are extremely vulnerable to earthquake loadings. An economic, environmental-friendly and less-intervention seismic retrofitting technique is required to reinforce these dwellings so as to increase regional seismic capability. A preliminary laboratory testing was conducted to investigate the enhancement of the seismic behavior of the rammed earth wall with externally bonded fibers. Different retrofitting materials and adhesives were tested to characterize their mechanical properties and bonding performance when externally glued on rammed earth blocks. The most suitable and practical retrofitting material and adhesive were chosen based on the experimental results. Furthermore, a numerical analysis was performed to investigate the improvement of the shear capacity of the rammed earth wall with the proposed technique. It was verified that the proposed retrofitting technique is a promising option for seismic retrofitting of rammed earth walls.

Abstract: Numerical simulation of the entire process of HRBF RC pile tip under the low cycle fatigue tests were carried out by nonlinear finite element software ABAQUS. The simulation results included hysteretic curve, skeleton curve, the equivalent plastic strain cloud, the concrete damage cloud and etc. On this basis, it is simulated and calculated by changing the strength of concrete, reinforment ratio, axial load ratio, strength of longitudinal reinforcement and stirrup ratio, to gain the effect of skeleton curve. FEA results show that: the results wear agreed well with the experimental results, and this method was proved feasible; high-strength steel could improve the bearing capacity of components, and its members had good energy dissipation capacity.

Abstract: The post-earthquake reparability of structures serves a crucial role in modern performance-based seismic design. However, due to intrinsic defects, traditional reinforced concrete structures continuously undergo significant residual deformation during earthquakes. As a result, the repair of these structures can be either technically challenging or economically inefficient. This paper contains a state-of-the-art review of post-earthquake residual deformation. Several technical methods to enhance the reparability of new and existing structures, which incorporate unbonded prestressed tendons or FRP (fiber reinforced polymer) materials, are introduced in this paper.

Abstract: In this research, analytical fragility curves for three existing structures are presented. Structures are 2-story, 6-story and 10-story residential reinforced concrete structures designed under dead ,live and seismic loads of zone 3 according to Egyptian code (2008). The design acceleration is 0.15g. The fragility curves are developed based on nonlinear incremental dynamic analysis of three dimensional structural models using SeismoStruct under twelve historic ground motions. Four performance levels are considered; fully operational, operational, life safe and near collapse.

Abstract: The focus of this research program is T-shaped CFT central column to steel frame beam connection. 3 joints with strong columns-weak beams and 1 joint with strong beams-weak columns 1:2 scale specimens were tested under constant axial loads and cyclic horizontal loads. Overall impact of axial force ratio and beam to column linear stiffness ratio on joint failure mechanism, hysteretic behavior, deformation ductility, and energy dissipation capability was investigated. Results showed that the failure mechanism for specimens with strong columns-weak beams was local buckling of the steel beam flanges and formation of the plastic hinges. There was minimum damage on the concrete column and joint panel zone. For a specimen with strong beams-weak columns, there was local buckling fracture on steel tube above and below the joint panel zone. Crushing of the core concrete was also observed with formation of the column hinges. It was found that both axial forces and beam to column linear stiffness ratio had impacts on joint capacity and ductility behavior of the specimens. Experiment results showed that the joint models had deformation ductility factor between 3.39 and 3.91 and viscous damping ratio between 0.46 and 0.51.

Abstract: Based on the design of the large-scale shaking table test of an underground pipeline under three dimension seismic excitation, the dynamic response of the soil-structure is analyzed by using ANSYS. In the numerical simulation, Drucker-Prager constitutive model is adopted to simulate the soil, the interface between soil and pipeline are simulated with zero thickness contact elements, size effects of test box are diminished by defining viscoelastic boundary around soil, the acceleration time history curve of the original earthquake wave is compressed and processed according to using the model scale similarity and energy duration which is presented by Trifunac-Brady [1] , and then the characteristic of seismic response of the pipeline can be found. The results show that the top of pipeline is the seismic response intense regional, deformation displacements of the central areas at the bottom and top of pipeline are always larger than others, the entrance and exit are the weak positions of anti-seismic structure; moreover, the dynamic response and interactions of soil-pipeline in the model experiment can be more accurately simulated by the methods presented in the paper. Thus, it can be served as reference for the design and construction of subsurface structures.

Abstract: The rapid development of modern seismic isolation technology has opened up new avenues of bridge seismic. For the bridge structure in highly seismic region,seismic isolation devices reduce the effects of the earthquake damage to bridges, but also reduce the ability of the bridge structure to resist other loads along with the increase of the displacement under seismic action. Nowadays, there are few engineering examples of the composite bridge with corrugated steel webs using seismic isolation technology. In this paper, we use Bridge Xiaoshagou as an example to study isolation technology with nonlinear time history analysis.

Abstract: Based on the horizontaldisplacements and loads of column at top end deduced according to sectionalbalanceable conditions at yield of high-strength frame columns, the lateralmaximum loads of column at top end calculated according to the Chinese currentconcrete code and involved regressive formulas, the resilience model ofhigh-strength concrete frame columns were established. The main results show:the resilience models of high-strength concrete frame columns proposed in thispaper consider influenced multi-facts and conveniently applied to engineering.

Abstract: Equivalent linearization method is widely used in seismic response analysis. For Chinese engineers and researchers, LSSRLI-1 and SHAKE2000 are good choices for seismic safety evaluation. There is large difference between the results of these two programs in moderate weak sites, which directs ways to improve them. The average spectrum ratio increases with response spectrum peak value of inputting wave moving from long period to short period. The shear strain obtained by the programs exceeds shear capacity, which is impractical. In the type III site, the weak foundation exacerbates the error. In the way to improvement, frequency components of inputting wave should be taken into account, and a further study on computation method of strain should be launched. For security purposes, seismic safety evaluation for major projects needs multiple method for reliability, especially constructions sensitive to shear strain.

Abstract: In the analysis of dynamic coupling interaction between wheel and rail, there are two kinds of models be widely applied, the Simplified dynamic model and the non-simplified dynamic model. And the calculation principles of these two models have been given in this thesis. At the same time, the calculation advantages and disadvantages also have been introduced. On the other hand, all the various factors which will affect the traffic safety have been summarized in this article, some measures also have been emphasized to avoid the derailment accident when the disaster is taking place.