The method of First Order Second Moment is used to establish the computational model of reliability index of each element, and reliability index of the globle structure is further obtained with the method of Point Eva...
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The method of First Order Second Moment is used to establish the computational model of reliability index of each element, and reliability index of the globle structure is further obtained with the method of Point Evaluation Technique. The statistical chracteristics of random internal forces of the structures is obtained using random perturbation methods, in which the random parameters of areas of cross sections of all the elements, area of cables , pretension of cables, external forces and stiffness of elastic restraint are considered. Some computational examples are put forward and the results are discussed to obtain some useful conclusions, which can be used as basis for design and safety evaluation of the prestressed steel structure. It is concluded that the randomness of restraint stiffness at boundary of the structure has great effect on globle reliability of the prestressed steel truss, and the effect decrease as the standard deviation of areas of cross section of steel cables becomes larger. Pretension of steel cables and area of cross section of the cables should be strictly designed for safety of the structures.
8 concrete filled circular CFRP-steel tubular flexural members and 2 concrete filled circular steel tubular flexural members are experimentally investigated. It is found that the load - middle span deflection curves f...
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8 concrete filled circular CFRP-steel tubular flexural members and 2 concrete filled circular steel tubular flexural members are experimentally investigated. It is found that the load - middle span deflection curves for members with longitudinal CFRP can be defined as the following stages: elastic, elasto-plastic and softening stage and that for members without longitudinal CFRP is similar to that of the concrete filled steel tubular flexural members. Within the factors scope of this test, 1 layer circumferential CFRP only has no significant influence on load bearing capacity of the concrete filled steel tubular flexural members. The ductility of the concrete filled circular CFRP-steel tubular flexural members is better than that of the concrete filled circular FRP tubular flexural members.
Fish bellied supporting system is a kind of supporting systems for point supported glass facades, which is popular with architects and widely used in many public buildings. Yet systematic research on its dynamic behav...
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Fish bellied supporting system is a kind of supporting systems for point supported glass facades, which is popular with architects and widely used in many public buildings. Yet systematic research on its dynamic behaviors still leaves much to be desired. Dynamic properties including influence of concentrative glass mass, wind and seismic responses of two types of fish bellied supporting systems are investigated herein. It is concluded that natural frequencies of vibration decrease apparently with the increasing concentrative mass, and the system becomes more flexible. The rise-to-span ratio and pretension in cables have more effects on frequencies of high order. Concentrative mass, pretension and rise-to-span ratio have great impacts on performance of the systems under wind loads. The node displacement and cable stress caused by earthquake is smaller than those caused by wind vibration. Earthquake has less effect on the fish bellied supporting flexible system.
A total of three interior diaphragm connections which had only three of the edges welded to the tubes for concrete filled square steel tube with different axial compression force ratios had been tested under low cycli...
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A total of three interior diaphragm connections which had only three of the edges welded to the tubes for concrete filled square steel tube with different axial compression force ratios had been tested under low cyclic reversed loading at the end of column to research the hysteric behavior, ductility, energy dissipation capacity and failure modes,. The only difference of all specimens was the axial compression ratio. Experimental results showed that the story drift ductility ratios are 3.38 to 3.48, the elastic and elasto-plastic story angular drift are 0.0075 to 0.0083rad and 0.0279 to 0.0286rad respectively, and the energy dissipation ratios are 2.674 to 2.903. The experimental results demonstrated that the local buckling of the beam flanges occurred before failure. The connection's strength, ductility and hysteretic behavior were analyzed, and the results indicated that all specimens had excellent energy dissipation capacity. And this kind of joint met the requirements of the current code GB50011-2001 for seismic design of buildings. The interior diaphragm connection, which have only three of the edges welded to the tubes, can be used for edge column connections. Additional seismic design recommendations were presented.
Some static performances for concrete filled circular CFRP-steel tubular flexural members were analyzed. It was found that the steel tube and CFRP tube could cooperate circumferentially and longitudinally from 0 load ...
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Some static performances for concrete filled circular CFRP-steel tubular flexural members were analyzed. It was found that the steel tube and CFRP tube could cooperate circumferentially and longitudinally from 0 load till the ultimate load bearing capacity. Circumferential strain does not distribute uniformly: circumferential tension strain at the point with the biggest longitudinal compression strain is the biggest and circumferential compression strain at the point with the biggest longitudinal tension strain is the smallest. For a same point, if it is compressed longitudinally, then tensioned circumferentially and vice versa. Steel tube longitudinal strain along the cross-section depth obeys the plain section assumption from 0 load till about 0.7 times the ultimate load bearing capacity. For members with the same steel tube outer diameter, steel tube longitudinal strain decrease as longitudinal CFRP layers increase at the same load level but their longitudinal strain are the same approximately when yielding. The deflection decreases as the longitudinal CFRP layers increase at the same load level and the longitudinal CFRP would enhance members' rigidity significantly. For specimens with the same steel tube confinement factor, the more the longitudinal CFRP layers, the larger the ultimate load bearing capacity. Ultimate load bearing capacity enhancement ratio increases as the longitudinal CFRP layers increase for members with the same steel tube outer diameter.
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