Advanced Materials Research Vols. 594-597

Abstract: In order to discuss the sensibility of influence line on the damage, a two-span continuous beam model is set up using the finite element method in the paper. The two damage positions at the middle span and 1/4 span are considered. And different damage degrees are simulated by the different crack depths. The shearing force and moment at four key positions of the beam are calculated under the moving unit load separately. Results show that the moment influence line at the middle support of the beam is very sensitive to the beam damage, while the moment influence line at other positions and the shearing force influence line at each position are insensitive. In the moment influence line of the beam middle support position, the obvious different values appear at the middle span when damage in the middle span. As damage in the 1/4 span, the obvious different also appear at the damage position, and the difference is increased unconspicuous up to the middle span, and then decreased soon. The conclusion is beneficial to determine the position of damage by means of comparing the moment influence line with that of undamaged bridge. Moreover, the difference value of moment influence line can also be used to estimate the damage degree.

Abstract: This paper is focused on the load distribution problem, which is especially concerned in design phase, for a long cantilever steel-concrete composite cable-stayed bridge with single tower and single cable plane. A large scale full-scale test is performed to make a systematical study on the load distribution coefficient under different conditions. A refined finite element model is gained by FEM software ANSYS to obtain the theoretical results, which are compared with measured data in model test. Finally, a suggested value of the coefficient is drawn through the test result.

Abstract: In China, the section 2.5.4 of《Technical Specifications of Urban Pedestrian Overcrossing and Underpass》CJJ69-95 stipulated: In order to avoiding sympathetic vibration and alleviate pedestrian’s sense of insecurity, the frequency of free vibration in the vertical direction of the upper part of the overcross should not be less than 3Hz[1]. Through discussing the rationality on this stipulation and analysing influencing factors of footbridges’ base frequency and its calculation method, limiting base frequency of simple supported beam footbridge with different span which Suits Chinese were drew up in this paper.

Abstract: With the human environment requirements gradually increase, besides the bridge construction in engineering structure function, the aesthetic requirements are also caused the wide attention, which hide different history and culture related with the current existing social reality. The history and culture are presented by many styles; the Chinese poetry is one of way in China bridge design and construction. This paper focuses on the aesthetic of Chinese poetry in the design of Chinese bridge construction and also points out the modern bridge design points.

Abstract: Based on summarizing three computational models of the rigid node model, the hinge node model and the model of semi-rigid node, the calculated length of scaffold are discussed. The application in the scaffold design of Tang Fang Ya Bridge with the resulting simplified formula shows that the hinge node model can ensure the overall stability of the structure effectively, but it is necessary to set oblique scissors appropriately to ensure the normal working of the structure.

Abstract: It is the same to structures on the ground, there’s many ways to reduce the damage which is caused by earthquake too. Mainly, there are two measures to absorb the shock on underground structures. The method of changing performance of underground structure will make construction cost enhance greatly, and the effect of shock absorption is not obvious also. The method of setting shock absorption layer can reduce the deformation and energy of surrounding soil transmits to the underground structure. It can solve the problem which earthquake creates danger to the underground structure essentially.

Abstract: In this paper, the elasto-plastic dynamic analysis on dynamic failure behaviors of steel double-layer grids supported by circumjacent steel 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: Along with the growth of the seismic wave peak acceleration (shorted as PGA), structure developed from elastic into the elastic-plastic. The failure model of the structure under the earthquake wave action is due to overall elasto-plastic instability of double-layer grids. When the structure reached its failure critical limit, the development of the plastic hinges is sufficient and 24.5% of the rods enter into their plastic stage; The ratio of its maximal failure node vertical displacement and its short span is 1/51, The ratio of its maximal failure node horizontal displacement and its columns is 1/49; Its critical failure PGA is 771gal, which is 1.9 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 7.6,which shows the structure owns good energy dissipation capacity.

Abstract: The traditional energy response spectra depend on the single-directional earthquake excitations and two dimensional dynamic analyses, in which the imbalance and coupled characteristics of multi-dimensional responses of structures are not considered. So, the energy spectra of constant ductility facotors are developed by considering the single-mass bi-degrees of freedom systems subjected to perpendicular bi-directional earthquake motions. The restoring force rule of single-mass bi-degrees of freedom systems is assumed as two dimensional yield-surface plasticity function. The relative energy spectra for input energy, hysteretic energy, kinetic energy and damping energy are presented and analyzed based on 34 pair earthquake motion records of hard soil site. Analytic results show that the energy spectra for hard soil site have their own characteristics, and the spectral forms and values are affected strongly by vibration period, ductility factor and period ratio of single-mass bi-degrees of freedom systems.

Abstract: The behavior of interfaces between coarse-grained soil and gravel-clay introduced by earthquake plays an important role in analyzing the stability of the impermeable structure in rock filling dams. Using the NGI-type simple shear apparatus, cyclic simple shear tests were performed to study the mechanical behaviors of the interface; shear deformations both along the interface and in the coarse-grained soil were analyzed. The test results indicate that: the cyclic shear strength of the interface was found approximately linearly proportional to the normal stress applied on the interface; meanwhile, the shear deformations reached their peak values in the first cycle, respectively; and the direction of initial shear stress significantly influenced the mode of relative displacement along the interface. In addition, shear shrinkage and shear dilation occurred alternately in each cycle. It also revealed that shear strength of the interface increases as the shear cycle increased and is approximately linear proportional to the normal stress level on the interface.

Abstract: Currently, losses throughout the disaster caused by the earthquake in rural areas represent a large proportion of the losses, and the probability of earthquakes occurred in rural areas is much higher than cities. Losses caused by earthquake disasters on rural are mainly the destruction of rural housing, which are about more than 80% per cent of total losses.Based on this, the research of mitigation measures,considering the new building materials and new seismic model,is carried out for the construction of new countryside in earthquake zone.The aim of the research is to strengthen rural areas of the seismic shockproof measures and provide new references to create harmonious security new countryside.