27 research outputs found
Effects of member loss on the structural integrity of tensegrity systems
Full text linkp. 2274-2285Tensegrity systems are statically and kinematically indeterminate systems. It may be
mistakenly believed that this inherent redundancy provides a large measure of safety
against collapse. However, a number of members are critical to system integrity, with the
loss of any of them likely to produce serious strength reductions. Furthermore, when these members are lost suddenly, their forces are shed into the structure in a dynamic manner, leading to yet more severe damage. This paper presents a numerical investigation into the static and dynamic response of plane tensegrity systems due to the gradual and sudden member loss. According to the results of this study, in some cases, the dynamic effect of member loss caused the occurrence of progressive collapse. It was shown that in several cases, static analysis cannot provide a correct and realistic picture of the behavior of the damaged tensegrity system and would lead to a significant overestimate of the load carrying capacity of the structure. The conclusions drawn from such a study can in turn, lead to the suggestion of some simple guidelines for the design of such systems.Abedi, K.; Shekastehband, B. (2009). Effects of member loss on the structural integrity of tensegrity systems. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/644
Seismic performance of bolted T-stub Beam-to-Box column connection
No full textUsing internal continuity plates in box columns due to accessibility problems and complicated detailing of connection was perceived as fraught with shortcomings and limitations. To overcome this deficiency, the effectiveness of external continuity plates in conjugation with T-stub connectors in I-beam to box-column connections under cyclic action is investigated in this study. Three damage control strategies based on the fuse action of T-stubs (T-F), strengthening the connections (T-S), and using reduced beam section (RBS) connections (T-R) are pursued and are compared to a corresponding end-plate connection (E). Nonlinear finite element analyses are conducted using the ABAQUS/STANDARD software on the connections under the qualification cyclic loading conditions to elucidate all the main seismic behavioral aspects, including the strength, initial stiffness, energy dissipation, ductility, von-Mises stress, and equivalent plastic strain distributions of models. First, the accuracy of numerical models is validated by a series of available experimental results. Then, a parametric study is performed on the effects of the moment ratio of the beam to column, the number of continuity plates, stiffeners embedded on the beam, and using high strength materials on the seismic performance of the connections. From the results, it is found that the T-S model was the most efficient among the different connections studied, supplying the stiffness, strength, energy absorption, and ductility increases by 2%, 21%, −17%, and 22%, respectively with respect to the E model, satisfying the requirements of AISC Seismic Provisions for SMF. Increasing the beam-to-column moment ratio and the number of continuity plates, had limited effects by less than 10% on the seismic performance of the connections. In the absence of continuity plates, the connections exhibited worse inelastic seismic performance with decreases in stiffness, strength, and energy dissipation up to 67%, 44%, and 74%, respectively. The T-F connection gained a 13% strength increase and satisfied the AISC requirements when high-strength T-stubs are used. Based on the numerical observations, design strength and rotational stiffness of the proposed connections on the component-based joint design strategies, are finally outlined.</p
INVESTIGATION INTO THE EFFECT OF INNER STEEL TUBE- CONCRETE COMPOSITE ACTION ON THE FIRE RESISTANCE OF CFDST COLUMNS
No full textAs an innovative type of composite construction, concrete-filled double skin steel tube (CDFST) has the potential to be used as columns in high-rise buildings. CFDST columns consist of two concentrically-arranged inner and outer steel skins with the annulus between the skins filled with concrete. Of prime features of CFDST columns is the interaction between steel tubes and concrete core. The confinement of the steel tubes on the concrete core benefits the interaction along the interfaces. However, when the interface interaction of steel tubes and concrete core vanish, the deformation starts to loom large. The deformation rate of the columns is increased under fire exposure. The current study aims to investigate the effect of interaction of concrete core and inner steel tube on the fire resistance of CFDST columns considering steel links (longitudinal stiffeners) embedded inside the concrete core welded to exterior surface of the inner tube. Finite element models for CFDST columns were developed using ABAQUS package in this study. A sequentially-coupled thermal-stress analysis procedure is conducted to evaluate the effects of inner steel tube- concrete interaction on the fire performance of these columns. The uses of stiffeners in the CFDST columns increase the fire resistance of the columns effectively. The specimens with stiffeners embedded in the exterior surface of the inner tubes exhibited excellent fire resistance. It can be attributed to the fact that interaction of stiffeners, inner tube and concrete core provides adequate bond and friction at the interface surfaces, contributing to the composite action improving strength during the process of
fire exposure. This implies that the interaction of concrete and steel components increases the fire performance of these columns significantly, a striking conclusion, which requires strategies to retain such performance. The conclusions, drawn from this study, can in turn, lead to the suggestion of some guidelines for the design of CFDST columns
Strength, stiffness, ductility, and dissipated energy reduction of semisupported steel shear walls (SSSW) due to a circular opening
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