Applied Mechanics and Materials Vols. 166-169

Abstract: The overall seismic performance of steel plate shear walls, including unstiffened SPSW, cross-stiffened SPSW, and SPSW with opening, SPSW with slits and holes, under low cyclic loading were tested. Contrastive analyze their hysteretic curve, loading capacity, lateral stiffness, ductility and energy dissipation coefficient. Results indicate that the unstiffened SPSW seem to be with high resistance lateral stiffness and carrying capacity; however its hysteretic curve show pinch effect obviously. When cross-stiffener was set on unstiffened SPSW, the resistance lateral stiffness and loading capacity can be significantly improved. However, the pinch effect of hysteretic curve does not distinctly change. The resistance lateral stiffness and loading capacity of SPSW with holes and slits is lower, however hysteretic curve is full. In addition, the energy dissipation capacity and the phenomenon which the thin steel plate shear wall shows the zero stiffness even negative stiffness at the point of zero displacement under cyclic loading are dramatically improved.

Abstract: In order to investigate the effect of steel fiber and polypropylene fiber on shear behavior of HPC deep beams, the shear tests were conducted on 18 different groups of deep beams with steel fiber and polypropylene fiber and 2 groups of HPC deep beams without fiber according to the orthogonal experiment. 6 factors, including the shape of steel fiber, the volume fraction of steel fiber, the aspect ratio of steel fiber, the volume fraction of polypropylene fiber, the ratio of web horizontal reinforcement and the ratio of web vertical reinforcement, were compared by direct-viewing analysis. Results illuminate that hybrid fibers greatly increase the diagonal cracking strength and shear strength of HPC deep beams. The aspect ratio of steel fiber plays the most important role in diagonal cracking strength whereas the ratio of web vertical reinforcement has minimum effect. Meanwhile the ratio of web horizontal reinforcement plays the most important role in shear strength whereas the volume fraction of polypropylene fiber has minimum effect. An anti-cracking capacity for inclined section calculation formula and a shear bearing capacity calculation formula for hybrid fiber reinforced HPC deep beams are put forward based on current code. Meantime test verification is carried out and the calculated results are satisfied.

Abstract: The taper work roll of the 1700 mm tandem cold rolling mills had some problems in the course of using, and the taper roll contour was ground difficultly and the difference between the designed contour and grinding contour was very big, and the work roll and backup roll had very serious and non-uniform roll wearing and even often had roll spalling, and above those problems affected the stability of rolling process seriously. After analyzing the structure and contour of the taper work roll, it was found that the work roll contour was designed unreasonably and the straight line part and the edge drop control part of roll contours were not connected smoothly, and so it lead to the local stress concentration easily in the transition region and a bigger contacting pressure peak between work roll and backup roll appeared. On basis of decreasing the contacting pressure peak and taking the width of rolled strip and the grinding contour length change into consideration, the design method of the edge control contour part of the taper roll was put forward. The finite element model was built with the software ANASYS9.0 to analyze the mill shape adjusting characteristics, and the simulation result showed that the newly-designed taper roll contour could improve the mill shape adjusting ability. It was shown in the rolling trial that the strip edge drop average was decreased from 14.9μm to 7.5μm and the edge drop fluctuation of strip was restrained to some extent and controlled within ±3μm.

Abstract: Existing models appropriate for design applications tend to overestimate the measured effective stiffness and are unacceptably inaccurate, because they generally neglect the influence of anchorage slip on the effective stiffness of the column. A three-component model that explicitly accounts for deformations due to flexure, anchorage-slip, and shear is shown to provide a more accurate estimate of the measured effective stiffness for the database columns. This model is simplified by neglecting small terms and approximating the results of moment-curvature analysis to obtain an accurate and rational effective stiffness model appropriate for design applications. Comparison the measured effective stiffness of reinforced concrete columns from the PEER Structural Performance Database with stiffness calculated following the FEMA 356. The FEMA 356 procedure substantially overestimates the stiffness of columns with low axial loads, in which there can be significant bar slip in the beam-column joints or footings. This model provides practical recommendations for improving estimates of effective stiffness.

Abstract: Using two or more different fiber mixed form high-powered composite reinforcement, through the control of the amount of fiber bundles, to "hybrid excellent", can not only ensure the tensile strength, and can effectively improve the toughness of the FRP bar . The paper based on the theory of the composite material hybrid effect of carbon fiber and glass fiber hybrid form the CGFRP bar hybrid mode, mixed ratio, hybrid effect analysis and research, this paper expounds the influence of the main factors CGFRP bar ductility, puts forward the CGFRP bar effect positive hybrid fiber critical size, stress-strain curve, tensile strength and elastic modulus calculation method, ensure the use of performance under the premise, and put forward the CGFRP bar design idea of reinforced concrete structure FRP ductility design, improve the safety of the structure provides an effective way.

Abstract: Rock strength is closely related to composition and internal structure of water-bearing rock. By using scanning electron microscopy, This paper analyses limestone composition and micro-structural damage mechanisms in the water physical and chemical effects. Besides, By combining with triaxial compression test according to natural state and saturated state of rock samples, and by applying mohr-coulomb strength criterion based on the basic concepts of damage mechanics, The paper obtains the quantitative expression of micro-structural damage by using statistical methods. Finally, The paper establishes the relationship between compressive strength and micro-structural damage and discusses evolution laws of micro-structural damage in limestone under complex stress state, The results show that degree of micro-structural damage increase as the water affection, further more, The correlations between micro structural damage and the compressive strength of water-bearing limestone shows a nonlinear relationship according to different confining pressure.

Abstract: Based on the experimental study, summarizes the disadvantages of the test roof; On the same premise of the roof to keep the overall appearance, the structural system of the roof is optimized ; The content of the optimized structural system includes the layout of the structural system, the establishment of the calculation model, the optimization of internal support system, the calculation of kinds of members, etc.; The integrity of the roof are enhanced after optimization, and more accord with the concrete shell space structure characteristics, and provided a convenient for the big water construction. Compared to the traditional roof, the optimized roof save about 30% of the costs.

Abstract: According to the confined characteristic of square concrete–filled steel tubular(CFST) column, core concrete zone was divided into the weak confined zone and the strong confined zone.A formula is derived for estimating the bearing capacity of square CFST column by analogy RC column with spiral stirrup. The proposed formula was used to calculate the existing experiments,the results showed that the computing values agreed well with the experimental values. The paper can be seen as a valuable guide for computing the bearing capacity of square CFST column.

Abstract: According to the Autoregressive Model in linear filter, the procedure, which was used to transform frequency domain to time domain, was programmed to simulate time history wind load with spatial correlation at different height of the tower by dint of numerical analysis software MATLAB. And then in virtue of the finite element software SAP2000, the nonlinear dynamic analysis to the steel structural tower under the time history wind load was made to gain the time history displacement, time history velocity and time history acceleration. Finally the comparison between static wind load displacement response and time history wind load displacement response was made to analyze the error of the static wind analysis.

Abstract: Six specimens, including 4 ceramsite concrete beams(one of beams mixed into the polypropylene fiber ) and 2 normal concrete beams, were tested to investigate the flexural behavior. The test results show that cracking load of ceramsite concrete beams is slightly smaller than the ordinary concrete beam and cracking load of ceramsite concrete beams has significantly improved after mixing into the polypropylene fibers. The ultimate load of ceramsite concrete beams are no less than ordinary concrete beam,and fibers have not effects on the increase of ultimate load. Load-deflection curves were compared,and the results show that stiffness of ceramsite concrete beam is less than ordinary concrete beam. Ductility of ceramsite concrete beam is poorer than ordinary concrete beam. Fibers improve the stiffness of ceramsite concrete beam. Cover thickness of concrete beam has little effect on the performance of ceramsite concrete beam.