The Static And Reliability Analysis Of Prestressed Composite Grids That Its Bottom Chord Bar Was Replaced By Prestressed Cables

According to Prestressed combined Nets and cooperative grids composed of prestressed cables and pole members, it presented prestressed combined Nets that contains cables and concrete slab that its top boom of the Nets was replaced by concrete slab and the bottom chord bar was replaced by prestressed cables. The design and construction of this kind of structure was studyed. Connecting nodes of web member-slab and web member-cable are prestened. The arrangement and anchoring of cable were prestented, and construction technology was prestented. Static and reliability while it was nomarl used were studyed. The results show that the structure static distrubtion rules are reasonable, and structure reliability that it was normal used is exccellent when the structure was acted by presented random variables including geometry size, material properties, prestress, dead loads and live loads.The static characteristics of prestressed combined Nets that contains cables and concrete slab was analyzed with Ansys finite element software. When model was found, the structure was dispersed with slab elements, beam elements, pole elements and cable elements. Static characteristics of a 20m×20m square structure was analyzed. The results show that the node displacement reaches the largest value in the center of the structure. And the node position is farther away from the center, the less of the node displacements.Also some plate elements have tension and others have pressure, so as the belly bars.The tension and pressure elements'positions are alternative. When the structure is forced by prestress and external load, the cables have tension. In addition , static characteristics of the square structure was analyzed when it was affected by different size prestress. The results show that the initial prestress is larger, the stress status of slab and web members are better. A 30m×20m rectangle structure model was formed that the static characteristics can be studyed sufficently. The results show that the static characteristics of rectangle structure is similar as square structure.The reliability was analyzed while it was normal used. While analyzing reliability, a certain property of the structure was regarded as the limit. When the reliability was analyzed with Ansys finite element sofware, the property is respective displacement and web member stress. When the model was formed, the assumption was same as the static characteristics was analyzed. The results show that the reliability that it was normal used is exccellent when the structure was acted by presented random variables including geometry size, material properties, prestress, dead loads and live loads. And the influence degree of random variables that they affect displacement and web member stress was gained. The conclusion can be referenced when the design and construcion are implemented.