Shape Optimization And Mechanical Properties Of Large Span Steel-coal-shed

With the continuous expansion of domestic thermal power scale,coal shed,as a place for thermal power plants to store coal,presents a development trend of full closure and long-span.Prestressed pipe truss is one of the main structural forms suitable for long-span fully enclosed steel coal shed project.The steel consumption of long-span prestressed steel coal shed is often thousands of tons,which has a large space for steel consumption optimization.The shape optimization of the structure can obtain considerable economic benefits.This paper mainly studies and analyzes two typical super long-span steel coal sheds of 150 m and 200 m.The steel coal sheds with two spans are prestressed pipe truss structures with three center circular lines.The specific research contents and conclusions are as follows:(1)Based on a single truss string,this paper explores the influence of different three center circular alignment,cable form and cable position on the mechanical performance of a single truss string string,and establishes the design principle of optimization analysis of the overall structure of steel coal shed: if the truss height is certain,the minimum n / M value should be taken for design on the premise of meeting the internal working space;The form of prestressed flat cable should be adopted;On the premise of meeting the internal working space,the anchorage position of the cable shall be as low as possible.(2)From the perspective of overall structure optimization,the effects of geometric parameters such as main truss height,truss thickness,truss longitudinal layout spacing and truss width on the total steel consumption of steel coal shed are explored,and the optimal design parameters and economic indexes of 150 m and 200 m span prestressed pipe truss steel coal shed are obtained.(3)On the basis of shape optimization,the force finding criterion of prestressed cable in steel coal shed is further explored,the cable pretension is optimized,and the appropriate cable specification is selected according to the cable force envelope value.The control criterion of cable prestress should be: under the load state of "1.0 dead load + 1.0 prestress",the relative displacement of anchor nodes at both ends of the cable should be controlled to be zero.(4)The elastic and elastic-plastic stability analysis of the overall structure of steel coal shed considering initial defects is carried out,and the overall stability is judged.The research shows that the most unfavorable load mode of the overall stability of steel coal shed is "dead load + Half span live load";The stability bearing capacity of geometric material double nonlinear analysis is the lowest,which is only about 50% of the geometric nonlinear stability bearing capacity under the same load mode.(5)The middle truss is selected for the transient dynamic analysis of cable breaking,and the time history dynamic response in the process of cable breaking is obtained.Through the pseudo dynamic analysis(static response × Dynamic coefficient),the influence of different cable break truss positions on structural response is explored.The research shows that the end truss string has little impact on the structure after cable breaking,and the overall structure is safe.The cable pretension of the middle truss string is larger,and the dynamic effect after cable breaking is also stronger than that of the end truss string.(6)Finally,the construction scheme of steel structure assembly and cable tensioning is formulated for the long-span prestressed pipe truss steel coal shed.Considering the construction steps,the mechanical simulation analysis of the whole process of structural construction is carried out to verify the rationality and safety of the construction scheme.