Study On The Calculation Model Of Spacious Buildings With Space Trusses

The spacious building structures with steel trussess was a hybrid structural system ,which was comprised of steel space trusses in the upper part and reinforced concrete structural systems in the lower part. in patial simplied engineering design,it was usually divided into two parts to design respectively. It was one of the most important problems that a large amount of engineers usually concerned about how to Simulate reasonably their interaction between the steel space trusses and the reinforced concrete structural systems by using some simplied calculation model instead of each.Centring on above-mentioned problems,some different simplied calculation models and a calculation model of the accurate whole structure were established in this paper to evaluate the rationality and the effectiveness of each simplied calculation model based on the calculation results ,which came from the comparison between the simplied calculation models and the accurate calculation model of the whole structure. At the some time,a preliminary study on earthquake input was carried out when we analyzed earthquake action in the simplied calculation model for the steel space trusses in the upper part.Finally,a study on the effect of dynamic characteristics and horizontal seismic responses of structures between elastic floor hypothesis and rigid floor hypothesis was carried out.The conclusions are as follows:①When we analyzed the force for the reinforced concrete structural systems in the lower part, That the in-plane flexural rigidity of the steel space trusses in the upper part was assumed to be infinite or the spatial effect of steel space trusses in the upper part was neglected but load would be unsafe to some members of concrete structures on force.②The in-plane flexural rigidity of steel space trusses depend mainly on its plane dimension and can be equivalent to a cast-in-place reinforced concrete slabs with 1mm to 3mm thickness.③To the steel space trusses in the upper part, it is the most reasonable that the model with activity hinge support in vertical direction and elastic support in horizontal direction was used to simulate the effect of the structure in the lower part on it under the static load condition in vertical direction.The model with the fixed hinge support in the two end or the model with the simply support used to simulate the effect of the structure in the lower part on it would cause that the force of some members of steel space trusses were unsafe. To those members especially which were joined by the support immediately, the sensitive degree of them will be more obvious.④When we analyzed horizontal earthquake action in the steel space trusses in the upper part,the internal force value of the members of the model with the ground wave input would be less than its exact value.It was unsafe.However, the internal force value of the members of the model with the floor-topping wave input would be more than its exact value.It was safe.⑤Under the rigid floor hypothesis,the stiffness of the whole structrue will become more rigid and may lead to be larger than under the elastic floor hypothesis on the earthquake action of it. When we compered the horizontal seismic shear force of some columns between under rigid floor hypothesis and under elastic floor hypothesis,it was both more and less and the discreteness of them was large.It was suggested that dynamic analyses for these structures should not be based on the rigid floor hypothesis.