Applied Mechanics and Materials Vols. 501-504

Abstract: Structural columns are very important members in steel buildings. An evaluation of fire resistance performance of the column is essential to sustain the structural stability in a fire situation. However, the length of columns is dependent on various architectural design variations. Therefore, the fire resistance can be different according to the length of column. In this study, to suggest the adequate fire resistance performance of structural columns by difference of length, an analysis was done based on an ordinary structural steels, SS 400, and hinge to hinge boundary condition. The result showed that the longer the column was, the less the fire resistance.

Abstract: This paper focuses on the structural analysis of concrete canoes. It firstly introduces the background of the concrete canoe competition and some typical FEA methods for concrete canoes. Then the paper establishes and analyzes an FEA model with SAP2000. Considering the similarity between concrete canoes and strip foundations under column, the paper uses the foundation engineering theory of strip foundations under column to determine the support conditions, and the applied loads of concrete canoes under 2 key loading cases. The result is proved to be accurate according to the experience of Tongji University Concrete Canoe Team. Finally, a conjecture of partial plane cross-section assumption of concrete canoe is proposed according to the result of FEA.

Abstract: The compressive capacity of composite foam sandwich tube is influenced by the fabrication process. Foam sandwich composite tube is made with technology of filled foam precut and curing molding together with prepreg ply. In order to clarify the interface to the bearing capacity, dynamics finite element software LS-DYNA was used to simulate the model whose interface is polished and waxed or not. The delamination was observed by the deformation cloud picture and displacement difference curve. The simulation showed that the composite foam sandwich tube which interface was polished and waxed before it was formed has relatively higher carrying capacity than that none-polished and none-waxed.

Abstract: Studies on size effect around deformation performance of RC members are carried out relatively fewer at present. This article evaluated bending deformation capacity and size effect characteristics of RC cantilever beams by means of test method. And decomposed various deformation components with size effect factors considered, including bending, shear and bar-slip deformation and so on. The article focus on discussing bending deformation components at different loading stage and putting forward corresponding distribution functions. Calculation and experimental results show that bending deformation characteristics have significant differences on specimen dimensions, especially in nonlinear loading stage after longitudinal reinforcement yielding. Large size members have a significant concrete crushing process. ductility reserves show a growing trend with specimens size increasing. Bending deformation ability depends on average stiffness along overall beam before longitudinal reinforcement yielding. After plastic hinge forming, its bending performance will be decided by average stiffness within hinge region equivalent length.

Abstract: Crack coalescence, which was responsible for some engineering disasters such as rock burst, and so on, was studied by one new numerical method-lattice cellular automata. A cellular automaton is made up of cell, lattice, state, neighbor and rule. It has advantages of locality, parallelization etc. Lattice cellular automata are presented which have the advantages of both cellular automata and lattice model. In this model cell will be connected with its neighbor cells in virtue of beams. The basic thoughts of LCA can be expressed as below. The heterogeneity of rock is introduced by randomly assigning the mechanical parameters of beams following Weibull distribution. According to equilibrium equations, deform equations and the constitute equations the local rules of cells can be constructed. Then lattice cellular automata were used to study the coalescence of two cracks with different geometries. The influences of arrangement and spacing of two cracks on the coalescence were studied. The numerical simulation results were in good accordance with the experimental results.

Abstract: According to the limit values of axial compression ratio of steel reinforced concrete given by technical specification for steel reinforced concrete composite structure (JGJ138-2001), the axial force of steel reinforced concrete sandwich nodes calculated by MIDAS and the axial bearing capacity calculated by limit values of axial compression ratio are compared with an actual project. The results show that steel concrete columns with designed strength of C60, the strength more than of column concrete strength higher than C50 is the least requirement as to meet the axial compression ratio. The result provides a theoretical basis for the future of safety work and the sandwich joint construction.

Abstract: This study presents an evidential uncertainty quantification (UQ) approach for dynamic response spectrum analysis of a structural system with epistemic uncertainty. The present method is performed using an evidence theory to quantify the uncertainty present in the structures parameters such as material properties. In order to alleviate the computational difficulties in the evidence theory based UQ analysis, a differential evolution (DE) based interval optimization for computing bounds method is developed. With comparison of probability theory and interval method, the computational efficiency and accuracy of this approach method are also investigated.

Abstract: Cable-braced grid shell is new single-shell form that is preferable to structural characteristics of glass skylight. Due to the cross diagonal cables arranged in the grid plane, the whole structure becomes a hybrid structure with superior mechanical properties, which combines advantages of rigid structure and advantages of flexible structure. Through finite element analysis, a circular steel tube cable-braced grid shell that has a span of 50 meters and with initial imperfections, is taken as an example in the paper. Numerous effects on the stability of cable-braced grid shell, such as load distribution form, height-to-span ratio, cross-sectional area of component and prestressed cable, are taken into comparison. The main factors which have effects on the stability of cable-braced grid shell are demonstrated, as a practical research reference for the future development of cable-braced grid shell.

Abstract: To study the seismic behavior of short pier shear wall, 6 short pier shear wall specimens are tested under low cyclic loading with axial load ratio of 0.2. Hysteretic rules and stiffness degradation rate are determined base on test results and feature points are defined by theory, restoring force model that considers the effect of two loading direction to hysteretic characteristics is proposed based on test research, which could be applied to the nonlinear dynamic analysis of the structure.

Abstract: As a new type of steel-concrete composite structure, Concrete-Filled Double Skin Steel Tubes not only have the advantages of the traditional steel concrete structures, but also carried out cross-section and great bending stiffness. This structure is widely used in high-rise buildings, bridges and power facilities. During the whole life cycle, concrete-filled double skin steel tubes may inevitably suffer from various impact loads. In current the research about steel-concrete composite structure focuses on the performance about axial compression, bias, bending, and low cyclic loads. but the research about it under lateral impact is equally import. In this paper, the behavior of concrete-filled double skin steel tubes (CFDST) with fixed boundary condition was analyzed by Finite Element Analysis method ,to analyze the destruction modal, impact force (F) , deflection () as well as other dynamic responses of CFDST under different lateral impact energy. The work mechanic and full range analysis of concrete filled double steel tube under lateral impact were analyzed. The results show that the damage of CFDST with fixed boundary condition under lateral impact is in ductile manner. Analyzed the whole process of the dynamic response basically , laid the foundation for further parametric analysis and practical calculation method.