Advanced Materials Research Vols. 243-249

Abstract: Double layer stirrup confined concrete columns use two layers of stirrup, inside and outside, to constrain the core concrete. In this paper, in order to analyze the effect of double layer stirrups on the axial compression characteristics of concrete square columns, to determine the strength and deformation characteristics of double layer stirrup confined concrete square columns, and to establish the bearing capacity calculation equation for double layer stirrup confined concrete square columns, we designed 16 specimens to conduct axial compression test, from which a series of test data were obtained for double layer stirrup confined concrete square columns. We built the bearing capacity calculation equation for double layer stirrup confined concrete components on the basis of analysis and study and compared the calculated values with the test ones, and these data fit well; therefore, the study can provide reference for design and application of double layer stirrup confined concrete square columns.

Abstract: Compared to the ordinary strength steel extensively applied in structures currently, high strength steel, a new kind of construction material, has many differences on mechanical properties. Though high strength steel has been applied in several projects in the world, which has obtained good effects, there is a lack of the design method for high strength steel structures and researches on the loading capacity of high strength steel members. To study the local buckling behavior of high strength steel members under axial compression, finite element models are developed to predict the loading capacity of high strength steel welded I-section and box-section stub columns under axial compression in this paper. With accurate simulation of 17 high strength steel specimens, the finite element analysis results agree well with the corresponding test results, and the average deviation of the ultimate loading capacity of 17 specimens is about -3.1%. It’s verified that the finite element models developed in this paper can accurately simulate high strength steel members with the initial geometric imperfections and residual stresses, and analyze the local buckling behavior of high strength steel members under axial compression. In addition, it provides a basis for the parametric study of high strength steel members under axial compression in future.

Abstract: The present paper is to analyses the key parameters of multi-reflection in GPR Survey. At first, it introduced the theory and methods for GPR result explanation. Then it proposed the necessity to work on multi-reflection analysis. For the complexity of multi-reflection, it emphatically worked on secondary reflection. According to the distinction of travel routes, the secondary reflection was divided into two cases. In the first case, the incident wave reflected twice at every interface and in the second case, the incident wave reflected for twice at every layer, meanwhile, the second reflected wave penetrated into the next layer as new incident wave. In these two cases, the amount of received waves was different and their corresponding transmitting parameters were deduced in the present paper. According to the deduction, in the situation of multiple reflections, the two-way travel time increases gradually; the energy decreases sharply and the profile curves are similar to each other.

Abstract: Steel fiber reinforced shotconcrete are widely used at home and abroad, compared to the ordinary modelconcrete, this process is not only convenient, fast, and often used in places with poor geological conditions. In this paper, we use mercury intrusion method to test pore structure of steel fiber reinforced shotconcrete, and analyze the change of pore structure under different construction techniques, and then from the microscopic point of view, analyze the effect on the mechanical properties and durability of steel fiber reinforced concrete under thus different construction technology.

Abstract: Connectors are the key element in steel and concrete composite structure. To research and develop new type connector for steel and concrete composite structure, a new type connector, corrugated rib connector, was developed. The base mechanical properties of this connector were tested by push-out tests. The test results shown the mechanical properties of this connector are excellent. Comparing to the push-out test results of perfobond rib connector, the shear strength of corrugated rib connector increased 24 percent than that of the perfobond rib connector, and the shear stiffness of corrugated rib connector is larger than that of the perfobond rib connector, Especially the ductility of corrugated rib connector is 1.9 times that of the perfobond rib connector when they reach the ultimate load. Based on the load-slip relation of corrugated rib connector by push-out tests, relative stiffness expressions under normal service state and ultimate bearing capacity state are obtained.

Abstract: A general analysis method of curved bridge, pure twist theory, which is based on the bar structure mechanical, has been introduced in this paper, by analyzing the basic assumptions of the theory, the limitations of application of the theory is indicated, while the ratio between the width and span of the curved bridge is out of the rang prescribed in the theory. The prestress effect is studied by the method of numerical simulation based on the finite element software ANSYS . According to the result, it can be indicated that, under the prestress, a horizontal and vertical displacement of the curved beam have occurred. The whole beam appears the tendency of turning outside, and there has been wavy distortion in the outer cantilever slab of the box girder along the span. The analysis result shows that, the method of the force analysis of spatial entities should be adopted when the ratio of width/span is small, and the difference between the inner vertical resistant reaction and the outer one caused by the prestressing force should not be ignored.

Abstract: Reasonable strong seismic motion records are selected according to the applicable Code of Seismic Design for Railway Engineering. By using FEA software, the FEA model of one double-column pier of passenger dedicated line is established with considering the effect of flexible base effects and seismic characteristic. Based on Park-Ang seismic damage model and nonlinear seismic response analysis, the seismic damage analysis on double-column pier of passenger dedicated Line is carried out. The study results are obtained as follow: 1) The seismic damage of bridge mainly happen during the early and middle stage of seismic motion. 2) There are still major discrepancies in the seismic damage made from the seismic records which come from the same site condition and have the same PGA. 3) Although PGA has a great effect on the seismic damage index, it has nothing to do with the happening time of max seismic damage index.

Abstract: The responses of a long span concrete filled steel tubular (CFST) arch bridge subjected to spatially correlated ground motion are analyzed. By using the stochastic vibration method, the time history of ground motion on the bridge site is simulated. The influences of spatial variation of the ground motion, such as uniform excitation, wave passage effect and partial correlation effect on seismic responses are studied based on the dynamic equilibrium equation for multi-support excitations. The calculated results show that the wave propagation influences the internal forces of the arch significantly. The effect of partial coherency is more complex compared to that of the wave propagation, yet it can be neither neglected. For long-span CFST arch bridges, it is critical to consider the effects of the spatial variation of ground motion.

Abstract: In this paper, we report on an analytical solution for beam-type skewed highway bridges subjected to truck loading. To confirm the analysis derivation and the solution obtained, the moment and shear responses to the design truck load are acquired using the analytical method for a number of typical US highway bridges and compared with those from numerical finite element method (FEM) analysis. In addition, the lateral distribution factors for moment and shear used in routine design are investigated based on comparison of the analytical approach and FEM. The analytical solution is shown in good agreement with the FEM result. Furthermore, the relevant provisions in the American Association of State Highway Transportation Officials' (AASHTO's) LRFD Bridge Design Specifications are also discussed here for comparison. It is observed that the design code specified load distribution factor may not predict well, especially for shear and/or severe skew.

Abstract: The large-span bridges always employ high-pile foundations, and its seismic response will take an important responsibility to affect the dynamic characteristics of whole bridge. In order to understand the effect of pile-soil dynamic interaction on dynamic characteristics and plastic development of the whole cable-stayed bridge system, the elasto-plastic seismic response of an actual cable-stayed bridge engineering considering material nonlinear was analyzed. And for reflecting the effect of pile-soil interaction, there were two modals applying to calculation. The results show that after considering pile-soil interaction, the structural actual dynamic characteristics can be more accurately reflected; pile-soil interaction performs a great influence on bending moment and shearing force of main girder and tower and the development of plastic zone get decrease. Meanwhile, Seismic wave chosen can greatly affect the response of structure. It will provide a basis for ensuring the ductility of structure and improving the seismic performance of structure.