Key Engineering Materials Vols. 302-303

Abstract: Cracking behavior of reinforced concrete composite floor slab, which has a significant effect on durability of concrete structures, is studied. Crack resistance of one-way composite floor slab is analyzed during transfer stage, handling stage, construction stage and serviceability stage, and calculation formulas are presented. Precast prestressed plank and topping cast-in-situ concrete layer can be designed as composite floor slab. It is assumed that prestressed unit is in elastic stage under service loads and hence every stress subentry can be calculated on the base of linear elastic theory and can be added linearly. For two-way composite floor slab, principal tensile stress in concrete is deduced on the base of theory of three-dimensional stress state in material mechanics. In addition, two-way effect on stress and practical distribution pattern of moment and shear force are considered. A number of structure experiment and experiences from engineering practice show that cracking behavior of reinforced concrete composite floor slab is a necessary consideration in design and analysis method shown in this paper is convenient and effective.

Abstract: The use of composite materials in structural engineering is recent, and researchers need to investigate their behavior features. A new unit of multi-ribbed composite wall is introduced. A multi-ribbed composite wall is the main bearing-load member in multi-ribbed slab structures (MRSS). The bearing-load characteristics and seismic properties of the wall are different from those of other ordinary concrete members In order to study seismic behavior and durability of Multi-ribbed composite walls, experiments of 26 pieces of composite walls under cyclic loading were carried out, and then the hysteretic model of shear force–shear deformation is established. The hysteretic curves of typical composite walls are calculated. The calculated curves agree well with the experimental ones. The damage model is quantified. This study introduces a quantitative analysis means for evaluating seismic behavior aspects of damage and durability of multi-ribbed composite walls.

Abstract: Based on the creep model of CFST members constructed with the Elastic Continuation and Plastic Flow theory of concrete creep and the creep theory of concrete under multi-axial stresses, the paper studies the load-carrying capacity of eccentrically compressed CFST members with consideration of creep. Some eccentrically compressed CFST members’ long-term loadbearing capacity is calculated and corresponding results are compared with the load-carrying capacity without consideration of creep. According to the analysis of calculating results, it can be concluded that creep will decrease the load carrying capacity of eccentrically compressed CFST members, and it should be paid enough attentions in actual engineering.

Abstract: In the present paper, two kinds of thick-walled hollow cylinders are studied. One is the cylinder with multi-layers and another is functionally graded cylinder. Both the cylinders are made of piezoelectric materials. Based on the basic piezoelectric equations, the exact solutions for the elastic hollow cylinder with N-layers submitted to external voltage are obtained. For the graded hollow cylinder the exact solutions are obtained by using displacement method and three hypergeometric functions. Comparisons demonstrate that the limitation of the multilayer cases is consistent with that of graded cases.

Abstract: As a new structural system, MRSS (multi-ribbed slab structure) has some applications in multistory building. But theoretical investigation and application study on multi-ribbed composite wall in high-rise building should be developed with various factors composing shear resistant capacity of wall under complicated loads. By means of model test and numerical simulation with FEM (finite element method), shear resistant expression of slab in tall building is set up and reliability index of a representative wall under small earthquake is figured out. Sensitivity of each factor affecting shear strength is evaluated. These works disclose the wall’s load bearing mechanism and make the structure application more feasible and assure the new system safety in practice.

Abstract: The paper presents a finite element analysis and static-load experimental verification on stress performance of corroded prestressed concrete bridge at Bai-Kong bridge of Shijiazhuang City on Beijing-Guangzhou Railway. At first, calculation of the actual bridge is simplified, mesh of the finite element of the bridge model is introduced, including the mesh of the finite element of undamaged bridge and the corroded bridge. For the situation above-mentioned, the finite element calculation result of the actual bridge is also presented in this paper. The graphic of the static load on the actual bridge and the testing spots distribution are described in this paper. Finally, the contrast between the static test result and the finite element calculation result is presented in this paper too.

Abstract: In the present paper, a long thick-walled piezothermoelastic hollow cylinder under a symmetric thermal loading is studied. Based on the theory of elasticity, the mechanical and electrical as well as the thermal fields of the cylinder are obtained. Besides, the effects of both temperature change and the material difference between two layers on the mechanical responses and electric output of the cylinder are investigated in detail. For comparison, some discussions of numerical results are addressed at the end of this paper.

Abstract: This paper discusses the suitability of using several creep theories of common concrete for creep of high-performance concrete (HPC). Based on the Age-Adjusted Effective Modulus method (AEMM) for creep of concrete, Improved Dischinger (ID) method and the Elastic Continuation and Plastic Flow (ECPF) theory for calculating relaxation coefficient and considering characteristics of HPC, a method is set up for calculating the creep of HPC under changing stresses, and comparing results gotten by the method with some experimental data, it can be considered that the above methods are suit for the calculation of creep of HPC.

Abstract: In this paper, in order to do research on the characteristics of reducing vibration and declining noise of concrete floating slab track, the vertical dynamic analysis model of vehiclefloating slab track is established with the use of finite element analyses method. By using this model, dynamic responses of floating slab track are studied under different conditions of train’s speed, stiffness and damping of infrastructure, structure size, etc. On the basis of this research, some suggestions for design of floating slab track are put forward.