Advanced Materials Research Vols. 639-640

Abstract: In this paper, the elasto-plastic dynamic analysis on dynamic failure behaviors of steel double-layer grids supported by tridimensional truss columns used in a gymnasium with the function of earthquake victims shelter under disaster earthquake is carried out under EL-centro wave with SAP2000, and the appraisal results on their anti-failure performances are presented under strong earthquake action based on the plastic-hinge theory. In the analyses, the geometric and material nonlinear effects are considered simultaneously based on the plastic-hinge theory. The plastic development level of the rod, the deformed shape and the failure type and the ductility are estimated by plastic hinge principle. The results show that the failure model of the structure under the earthquake wave action is the complicated combination of strength failure and elasto-plastic dynamic local buckling in deferent areas of the structure; When the structure reached its failure critical limit, the development of the plastic hinges is not sufficient and only 9.99% of the rods enter into their plastic stage; The ratio of its maximal failure node vertical displacement and its short span is 1/331, which can meet the need for flexible non-structural attachment; The ratio of its maximal failure node horizontal displacement and its columns is 1/166; Its critical failure peak acceleration of EL earthquake wave when applied in the combination of three directions is 602gal, which is 1.5 times more than the official seismic fortification level of 8 degree (major earthquake, 0.2g) and can be served as earthquake victims shelter in the area of 8 degree seismic fortification; Its displacement ductility coefficient is 5.65,which shows the structure owns good energy dissipation capacity.

Abstract: Buckling-Restrained Brace (BRB) consists of energy dissipative core and a strengthening tube to prevent buckling when subjected to compression. Under cyclic loading, BRB exhibits elastoplastic hysteretic behavior, which leads to certain amount of permanent displacement in the structure after medium to severe earthquake. Residual deformations can result in increased cost of repairing. An innovative BRB device called Self-centering Buckling-Restrained Braces (SC-BRB) is devised to control maximum and residual drift of steel moment frame buildings subjected earthquakes. The SC-BRB is composed of the BRB energy dissipating cores which are responsible for energy dissipation, and the self-centering system which makes BRB energy dissipating core return to its initial position upon completely unloading. By exploring the mechanism of SC-BRB, it is found that to ensure fully self-centering capacity, the self-centering bar should have sufficient elongation capacity as well as considerably large elastic modulus which could afford stiffness in real structures

Abstract: It is commonly considered that liquefaction of sandy soils is the important reason for earthquake-induced landslides,but it has been reported liquefaction phenomenon can also occur in clayey soils in the recent research. In order to clarify liquefaction potential in clayey soils ,a deeper study was conducted on the basis of field investigation and a series of laboratory tests including undrained cyclic ring-shear tests on the clayey soil samples collected from the sliding zone of the Wenchuan earthquake-induced landslides. Results show that the liquefaction potential of clayey soils is lower than that of sandy soils given the same void ratio; the soil resistance to liquefaction rises with an increase in plasticity for clayey soils; It is useful to estimate the liquefaction potential of soil by means of plasticity index and the liquefaction potential of soil in practical engineering applications.

Abstract: Augmenting the flexural strength of columns in the seismic design of reinforced concrete (RC) moment resisting frames is a key measure among all the detailing procedures of seismic capacity design, which induces the desirable beam side-sway mechanism for the structure to dissipate energy during a strong earthquake. The objective of this paper is to assess the influence of various strong column factors which is employed to perform seismic vulnerability analysis to the seismic performance of a six-story deterministic RC frame structure. Seismic vulnerability analyses indicate that augmenting the flexural strength of columns is an effective measure to improve seismic performance of RC frame structures. Increasing strong column factor improves the displacement capacity of structure and induces the biggish grads between the different damage limit states, which provide caution to prevent the abrupt collapse of structure during a strong earthquake. Seismic vulnerability curves provide the quantitative criterion for evaluating the seismic performance of structure and choosing appropriate target strong column factor.

Abstract: The orthogonal polynomial expansion method expression of stochastic structure was deduced. Then, based on orthogonal polynomial expansion method, taking a 20-storey reinforced concrete frame structure as an example, the impact of the randomness of structural parameters on time history response was researched. Meanwhile, in order to verify the correctness of analysis program, the calculation results of orthogonal polynomial expansion method were compared with the Monte-Carlo method which based on Newmark integral. The results show that it can get relatively accurate results when the number of terms of the orthogonal polynomial is 5. Structural mass and stiffness have a greater impact on the structural dynamic response. And the greater number of random parameters, the greater the impact on structural dynamic response.

Abstract: In order to study the mechanical characteristics and the shear failure behavior under earthquake action, a single-storey single-span RC frame structure strengthened with Y-eccentrically brace were designed and manufactured to be 1/3 scale. The pseudo-dynamic testing method was carried out under El-Centro earthquake action with different peak acceleration adjusted by Code for Seismic Design of Buildings in mainland China. The testing result indicates that RC frame structure strengthened with Y-eccentrically steel brace presents perfect seismic performance under strong earthquake action, at one time, the seismic performance maybe affected by the length of outsourcing steel at the joint between energy dissipation element of eccentric steel brace and RC frame beam. The joint should be considerably designed to make sure that shear failure can firstly occur in energy dissipation element.

Abstract: The probabilistic characteristics of the seismic performance indices for the compression-bending reinforced concrete columns were studied, which is important for the Performance-Based Seismic Design (PBSD) and seismic performance evaluation of civil engineering structures. First, five damage states with four limit states were defined for the seismic performance level of ductile reinforced concrete components, along with the strain limit definition for each limit state. Then, based on the mechanical behavior and statistical characteristics of reinforcement and concrete, the deformation characteristics of circular reinforced concrete ductile component were analyzed probabilistically for each performance level. Hereby the probabilistic distribution characteristics of the performance indices for each performance level were obtained, and the regression formula as well as its probability distribution model for the performance index of each performance level was proposed, which can be used in the probabilistic analysis of seismic performance of civil engineering structures.

Abstract: Suspended dome is a reasonable and novel type of long-span hybrid spatial structures based upon single-layer spherical lattice shell and tensegrity system. Based upon the structural force-bearing characteristics, the combined finite element model of beam elements, truss elements and cable elements is set up. A method taking the maximum displacement on nodes under earthquake acceleration of each level as dynamic response representative parameter is proposed to study the dynamic stable ultimate capacity of suspended dome by application of the incremental dynamic analysis in combination with B-R kinetic criterion. Furthermore, considering suspended dome has the clear advantage over Single-Layer Spherical Lattice Shell for a structure with a long span and a small ratio of rise to span, the influences of factors such as structural parameters, geometric parameters, and different earthquake input are investigated on dynamic stability for a kiewitt-type suspended dome with a long span and a small ratio of rise to span. Finally of suspended dome some conclusions are obtained such as the initial defects can clearly reduce dynamic stable ultimate capacity, and since the rise-span ratio, pre-stressing level and cross section area are not monotonous as variety to the structural dynamic stability, they should be optimized to enhance or improve the structural dynamic stability, which can be rules for engineering design.

Abstract: A certain amount of viscous dampers are installed in the 10-storey frame structure in line with different distribution strategies, and then 2 sets of strong earthquake records and 1 set of artificial acceleration time-history curve are selected to conduct the time-history analysis under both frequently and rarely earthquakes via ETABS software. Based on the comparison of the time-history analysis results in various working cases, the ideal energy dissipation results can be obtained when the dampers are installed in the lower stories with a larger storey drift, which also help to utilize the upper space of the structure. The time-history analysis shows that the viscous dampers installed in the lower part of a building have a better effectiveness of vibration isolation than those in the upper parts, and it is no necessary to install too many dampers, for the energy dissipation effects tend to be steady when the number of dampers has been increased to a level.

Abstract: In previous earthquakes, masonry structures, especially those masonry structures with prefabricated slab was damaged severely, and caused heavy casualty and property losses. In order to improve the seismic behavior of prefabricated slab, a new type of prefabricated slab with longitudinal and transverse joint steel bar was designed. By employing a numerical simulation procedure, LS-DYNY3D, models were established, and their seismic behaviors were analyzed .The results show that, the masonry structure of new type prefabricated slab with longitudinal and transverse joint steel bar is better than the structure with traditional prefabricated slab in structural integrity and stability. That is to say, its seismic behavior is better than the masonry structure with traditional prefabricated slab.