Research On Application Of Assembled Cable Supported Lightweight Concrete Composite Structure

The cable supported concrete floor structure is a new type of prestressed composite structure,which is suitable for the floor and roof structure of large columnless space.It can also be applied to urban large-span pedestrian overcrossings after reasonable design.It has a good application prospect.By improving the problems of low construction and assembling efficiency,heavy slab and complex fabrication of struts,a new-style assembled cable supported lightweight concrete composite structure is put forward.Depending on Hebei Natural Science Foundation of China《Theoretical and Experimental Study on Mechanical Properties of New Type Cable Supported Ribbed Beam Composite Bridge Structure》,the finite element analysis method will be used to refine the basic structure and propose a reasonable structural form.The basic mechanical characteristics are analyzed to reveal the mechanism of the force and the influence of the main design parameters,and the design method is determined.Finally,through the design cases,the assembled cable supported lightweight concrete composite structure is applied to the stadium building and the urban pedestrian bridge.The main contents of the research are as follows:(1)Based on the structural mechanical properties,the construction of this structure is researched in detail,and the reasonable prefabricated lightweight concrete slab,the connectors among the slabs,the cable-strut system and the connection joints are determined.(2)The finite element analysis of the force mechanism,mechanical state and natural vibration characteristics of the assembled cable supported lightweight concrete composite structure at different stages is carried out.(3)The influence of main parameters,such as sag-span ratio,slab thickness,ribbed beam depth and width,and concrete material changes on the mechanical properties of the structure is studied.(4)The theoretical analysis and reinforcement design of the upper prefabricated lightweight concrete slabs are carried out.The mechanical properties of the connectors between the slabs are studied and the influence of the main parameter changes on the mechanical properties of the structure is analyzed.(5)The structure is applied to a university gumnasium in Shijiazhuang City and a pedestrian bridge in North Second Ring Road of Shijiazhuang,and the structure is designed,calculated and stressed to verify the applicability of the structure.Through the above research,the main conclusions are as follows.The reasonable construction of the assembled cable supported lightweight concrete composite structure is proposed,the prefabricated trough-shaped lightweight concrete and steel truss composite slabs are employed,which ensures the large rigidity and light self-weight of the structure and significantly enhances the construction and assembling efficiency.The H-type short steel beams are adopted as connectors among the slabs,which can enhance the integrity of the structure during tensioning.The strut with one single vertical steel tube is adopted to simplify the construction.The force mechanism and mechanical properties of the structure are clarified,and the structural force transmission is simple and the mechanical efficiency is high.This structure is provided with low rigidity and its low order modes are mainly vertical vibration.The fundamental frequency of the structure is small,around 2.98 Hz.In addition,the sag-span ratio has little impact on the natural vibration characteristics of the structure,the ribbed beam depth and width have a relatively large impact,whereas the slab thickness has a greater influence,especially on higher order modes.The structural efficiency can be improved with the sag-span ratio appropriately increased.With the increase of slab thickness and ribbed beam depth or width,the global stiffness of the structure can be increased to a certain extent,but the self-weight of the structure will be increased as well.In addition,the internal force and deformation of the structure adopting light concrete are smaller than those adopting ordinary concrete,with the deformation reduced by within 5 mm and the internal force by 36.84%,which shows that the mechanical properties of the structure are significantly improved with the use of lightweight concrete.With the increase of the H-type short steel beams depth and width,the deformation of the structure tend to increase and decrease,respctively,while the maximum bending moment around Y axis in the plate decrease first and then increase.Increasing the H-type short steel beams flange thickness,the deformation of the structure and the maximum bending moment around Y axis in the plate are steadily decreasing,while the web thickness is the opposite;Applying the structure to astadium and overpass,the internal force and deformation meet the requirements of the specification,the application of the structure is reasonable.