Advanced Materials Research Vols. 243-249

Abstract: The deformation calculation formulas under long-term and different loading of prestressed steel reinforced concrete beams are built up by using age adjusted effective modulus method according to internal force equilibrium and strain harmony of section. Based on that, numerical methods are applied to calculate and analyze stress redistribution of steel and concrete, deformation of beam in different time slice, as well as the curves about how concrete strength, axial force, moment, volumetric percentage of steel and volumetric percentage of tendon affects mid-span deformation of long-term loading beam.

Abstract: On the assumption that the concrete is a multi-phases composite material composed of matrix, aggregate and the bonding interface, the failure progress of concrete is simulated. It requires that numerical method not only can simulate forces and stresses, the failure growth and contacts, but also can simulate the discontinuities such as joints and cracks，the large deformation after the failure and the propagation of multi-cracks. By adding the function of tracing the propagation of cracks，the Numerical Manifold Method proposed by Shi Genhua is developed which can simulate both the discontinuity of block system and the tensile or shear failure of intact block. The random aggregate model according to the Monte Carlo method and Fuller Graded Formula is carried out, and the concrete fracture process is simulated by the NMM. The strength and failure pattern are in good agreement with the experimental data, which shows that the method put forward and the program developed in this paper can effectively simulate the fracture process of concrete composed of multi-cracks.

Abstract: To large span spatial structures, the displacements and internal forces caused by temperature loads and support settlements cannot be ignored. Beijing Jiangtai winter garden mainly consists of reticulated shell and glass curtain wall. The reticulated shell is composed of 9 spatial arches and other common frames, thus it can be seen as arch-reticulated shell hybrid structure. The two ends of the arches are supported at the top of steel columns and concrete walls separately. The glass curtain wall is fixed to vertical cables. This paper chose eight load cases including temperature loads and support settlements, and used ANSYS to analyze static responses of the structure under such load combinations. The comparative results showed that temperature loads had more effect on the structure’s load bearing capacity than support settlements. And the superiority of hybrid structures was fully embodied in the conclusions of this paper.

Abstract: The 3D nonlinear FEM models of concrete-filled square tubular column with internal diaphragms and steel beams with reduced beam section bolt-weld joints, involving geometric, materials and contact nonlinear were founded. The results of FEM are agreed to that of tests, so we can conclude that FEM in this paper is correct. Then the bearing capacity behavior of joints under cyclic loading are analyzed, including P-Δ skeleton curves, P-Δ hysteretic curves, the dissipating energy ability and destruction form. The analysis results show that the plastic hinge in the joint with reduced beam section is removed to the reduced beam region. The joints that studied in this paper present excellent ductility and dissipating energy ability, therefore, all of them have a good seismic behavior.

Abstract: On the basis of previous experimental research, the nonlinear finite element analysis of the eccentric in-plane beam-wall joint is made with nonlinear bond-slip constitutive relation between steel and concrete. The mechanical behavior of the joint is studied in detail, and parametric analysis is carried out for mechanical behavior of the joint. Results of experiment and nonlinear analysis proved that: the important guarantee for mechanical behavior of the eccentric in-plane beam-wall joint is macro resistance capability, which is a precondition of local force transmission of the joint. In addition, the length of beam plunging wall, eccentricity of the joint and the stirrup ratio of beam within wall are the main factors influencing on mechanical behavior of the joint.

Abstract: Soilbags have been understood to have the effect of vibration reduction and can be used as a kind of base isolation in building foundations. In this paper, a series of cyclic simple shear tests were carried out on soilbags filled with three kinds of soils under different vertical stresses to investigate the damping and stiffness characters of the soilbags. The results show that soilbags have a relatively high damping ratio and variable horizontal stiffness so that they can be used as base isolation materials.

Abstract: The steel structure of Hefei Xinqiao International Airport Terminal was taken as a background of this article. The large-span frame is a typical frame of the structure. The curved box-girders are the critical parts of the whole frame. This paper focused on the mechanical properties of the curved girders, as well as the influence on box-columns connected with them. Stability problem is a key problem in the steel structure design, and effective length factor is a way to reflect the stability problem in code for design. In this paper, the whole model of the airport terminal was established to conduct eigenvalue buckling analysis to obtain effective length factors of the box-columns connected to the curved box-girder. In the finite model, a unified axial force was applied on the end of the box-column, and the elements of the box-columns and the adjacent members were refined. Then the effective length factors were derived through the buckling models. In this paper, the curved box-girders of Hefei airport building were studied using finite element software ANSYS. The local model of the curved box-girders were set up to study the mechanical properties of the curved girders including the ultimate capacity analysis. Parametric analysis of the girders was carried out, and the results could be used to guide the design. The results show that finite element method is a convenient way of calculating effective length factors for members with complex boundary conditions, and analysis of local models provides reasonable suggestions for design.

Abstract: Based on the experiments of four bond-retarded prestressed concrete continuous beams, an unbounded prestressed and a bonded prestressed concrete continuous beams, this paper analyzes the ultimate bearing capacity and the deflection of the continuous beams by comparing the theoretical and experimental results, shows that the bond-retarded prestressed beams has the same character with the unbonded prestressed beams when retarding mortar is not hardening; while the bond-retarded prestressed beams has the same character with the bonded prestressed beams when retarding mortar is hardening.

Abstract: The present standards for designing of ultra-long pile exist the contradiction between theory and practice; By combining the projects and finite element calculation and analyzing the characteristics of force and deformation, we can get the conclusion that there is asynchronous nature between the side resistance and the tip resistance in different soil layers. Meanwhile, the pile tip resistance has not been fully realized. To solve the above problems, I put forward reasonable proposals in order to make up for the deficiencies in designing. Introduction

Abstract: The cyclic loading pushover method which can simulate the real ground motion are suggested, and the target displacements of cyclic loading are discussed to overcome the drawbacks of traditional Pushover method which cannot consider the important seismic response of plane frames under earthquake, such as cyclic loading history, duration of strong motion, and the cumulative damage of structures. Through the comparison analysis of the story drift and hysteretic energy of plane framed structures gotten by adopting cyclic loading pushover method, traditional pushover method, and dynamic elastic-plastic time-history analysis method respectively, the conclusion that cyclic loading pushover method can better reflect the loading process with ground motion and the cumulative disruptive effect caused by hysteretic energy of structure can be obtained ,which provides some references for performance evaluation of elastic-plastic analysis of seismic structures.