Advanced Materials Research Vols. 243-249

Abstract: Based on bending fiber reinforced concrete beam, through the nonlinear analysis, the paper discuss the constitutive models of concrete and reinforcement, the properties of their element and the models of concrete beams reinforced with FRP bars. Using nonlinear analysis and comparing numerical results with experimental results, the fiber reinforced concrete beam bending terminal numerical model constructed in this paper can simulate the entire process of internal force and deformation of fiber reinforced concrete beams, and describe cracks in the formation and extension and the failure process and failure form, which also can provide enough precision to the practical engineering and scientific research. Meanwhile, the finite element computation model verified by test can provide more reactive information to effective structure computation model.

Abstract: A nonlinear finite element model of fixed ended cold-formed steel stiffened lipped channel short columns with and without perforations was developed and verified against experiment results. Material and geometrical non-linearities were included in the finite element model. It was proved by comparison analysis that using weighted average tensile yield stresses of the flat and corner areas and the mean geometrical imperfections along the length of the specimens was suitable for predicting the failure mode, ultimate load and load versus displacement curves of the channel short column. The results got by FEA coincided with the experimental results.

Abstract: According to liquid-solid coupling vibration analysis model of reinforced concrete rectangular liquid-storage structure on Winkler elastic foundation, and assuming that liquid is ideal. According to existing literature, for the sake of engineering application, the influence of dimensionless parameters on liquid-solid coupling vibration frequency of rectangular liquid-storage structure is discussed. And so a theory base about the design calculation of rectangular liquid-storage structure is provided for subsequent engineering structure.

Abstract: Nonlinear properties of materials will be automatically ignored while structural dynamic analysis in ANSYS. And the energy method principle is used to analyze. So it can not be used to calculate the frequencies and modals of prestressed concrete structures directly. Accordingly, prestressing force applied to beam with initial strain method in ANSYS calculate in this paper. The perstressing force influence of the beam is changed to the impact of element materials elastic modulus. Analyze the frequencies and modals of prestressed concrete beams with ANSYS computational procedure by modified ANSYS model. The calculated natural frequencies at all levels prestessing force fit close with the experimental results. It shows that modified ANSYS finite element analysis model is feasible.

Abstract: The unbonded prestressed concrete slabs is usually used in big span high-rise buildings. Due to the existence of stairs, elevators, piping shafts and washroom etc，（hole drilling is usually encountered in the floor of unbonded prestressed concrete structures）, which weakens the rigidity of concrete slab, and it has different influences on the slabs with openings in different locations. Based on the contrast experiments of the unbonded prestressed concrete slab with openings in different locations subjected to uniform load, this thesis investigates and analyzes mechanical behavior of the unbonded prestressed concrete slabs with openings in different locations (central，around edge and corner) subjected to uniform load. Using the yield-line theory to calculate the ultimate bearing capacity of pre-stressed slabs with openings, and comparing from experimental results to theoretical ones, this paper puts forward some conclusions of how different opening locations impact the ultimate bearing capacity of pre-stressed slabs with openings

Abstract: In order to investigate the failure mechanism,failure mode and hysteresis curves of the low strength row-lock cavity walls strengthened with HPFL(High Performance Ferrocement Laminate), eight pieces of rowlock cavity walls subjected to low-frequency cyclic loads and a constant-amplitude vertical load on top were tested, and the results showed that the bearing capacity, ductility and energy intensity all were greatly improved on the basis of comparison and analysis of the seismic behavior influenced by different strengthening methods. In addition, this article proposed the calculation formulas for reinforcement design reference .

Abstract: In this paper, beginning with the mechanism of secondary moment, the calculated difference of secondary moment between slab-column structure and skeletal structure is indicated, and the secondary moment distribution of prestressed slab-column structure is provided by finite element analysis. The effect of edge beams setting or not and arrangement types of prestressing tendons on the magnitude and distribution of secondary moment is analyzed, and the magnitude relation between secondary moment and external load moment is compared. It can be served as reference to understand the distribution of secondary moment and design slab-column structure reasonably.

Abstract: Cracking is the most common damage in the secondary lining concrete because of its continuous thin-walled structure, potential surrounding rock pressure and poor curing conditions. In order to improve the fatigue and gas perimeability resistance of concrete and to reduce the responding costs, four series modern concretes including ultra-fine pozzolanic powder and organic fibers are prepared and investigated. The optimized modern secondary lining concrete is determined as the concrete including 0.08% or 0.1% volume fractions of ultra-fine organic fiber (UF), based on the test results of fatigue life and coefficient of gas-permeability under fatigue loading. The result show fiber concrete is positive for enhancing the fatigue and gas permeability resistance and can apply for the tunnel secondary lining.

Abstract: Fire resistance design of Reinforced concrete wall is one of the important issues for structural safety. The sequentially coupled thermal-stress analysis method in ABAQUS software is used to calculate the fire resistance of walls. The results of a parametric study to examine the influences of parameters, such as axial load level, lateral load level, height-to-thickness ratio, wall thickness, material strengths, steel reinforcement ratio and concrete protection thickness to reinforcements on fire resistance of RC walls are presented.

Abstract: There are plenty of pipes to be arranged in subway station platform. Optimizing the air-conditioning system ducts is especially important because of its large size. Due to the location of stairs and the size of ducts, the platform exhaust ducts of a Shanghai subway station were laid out within the range from the stair to the end of the platform which probably can’t exhaust smoke effectively in fire. In reconstruction plan, air supply ducts and discharge ducts are connected and valves are added. Air supply pipe can be changed into discharge duct by controlling the valves. The smoke extraction performances of the original plan and the reconstruction plan are analyzed with the CFD numerical simulation. The results show that the reconstruction plan can make up the shortcoming of the original plan and contribute to the layout of pipes in new platform.