Study On Basic Theory And Method Of Steel-Concrete Composite Tension Problem

Steel-concrete composite tension is a basic mechanical behaviour in both reinforced concrete(RC)structures and steel-concrete composite structures.Because the structures utilize both steel and concrete materials,and more important,the tension/flexure/shear/torsion issues can always be saw as a steel-concrete composite tension issue on the principle tensile direction.However,the steel-concrete composite tension issue hasn't been thoroughly studied because of the complex fracture mechanism of concrete and the behaviour of the steel-concrete interface.Thus,in this dissertation,the tensile mechanism of reinforced concrete(RC),concrete-filled steel tube(CFT),and steel plate-concrete composite(SPCC)panel are investigated theoretically,experimentally,and numerically.The main works and conclusions are as follows:(1)For the RC tension issue,an elaborate theory,named b-ellipse model,is proposed.The general formula for calculating crack width is proposed.The tension stiffening-tension softening fuzzy issue is cleared.(2)The RC tension theory is applied to the nonlinear crack width analysis of structures.On the MSC.MARC(2010)platform,A specific fiber beam-column element geared for the FEA-based nonlinear full-process crack width prediction is developed.The developed element is verified against totally forty-six specimens of various test results in the literature.The developed element is then applied to the elastic-plastic time-history analysis of a RC building,realizing the full-process prediction of complicate crack width distribution of the entire structure under earthquakes.(3)Six CFT specimens and two hollow tube specimens are tested.An elaborate theory,named c-ellipse model,is proposed.Design formulas,equivalent constitutive laws,and fractal cracking laws are developed.(4)The CFT tension theory is utilized in the lateral stiffness analysis of pier structures.On the MSC.MARC(2010)platform,A specific fiber beam-column element considering the confining effect of CFTs under tension is developed and verified.The developed elemet is utilized in the lateral stiffness analysis of pierstructures.(5)Six SPCC specimens are tested.The tension-stiffening,confining-stiffening,and tension-stiffening degradation are investigated.Equivalent constitutive laws are developed.(6)The SPCC tension theory is utilized in the shear analysis of SPCC structures.On the ABAQUS 6.10 platform,A planar membrane element is developed geared for the nonlinear shear analysis of SPCC structures.Six SPCC beams are tested and simulated by the developed elemnt,indicating that the developed planar membrane element that utilizes the SPCC tension theory is capable for the shear analysis of SPCC structures.