| Because of the large span of space truss,the change of bearing form and the large size of buildings,the construction of large-span space truss needs to improve the complexity and refinement of space steel structure construction.Therefore,higher requirements are put forward for the analysis of construction process and the innovation of construction technology.According to the use requirements and design characteristics of the steel structure of the protection shed of Qingong No.1 at the site of Qinyongcheng,this paper elaborated in detail the key technology of sliding installation of large-span pipe truss across deep foundation pit,effectively solved the objective factors of the absence of large-scale lifting equipment around the foundation pit,and reasonably solved the installation and monitor of structure ensuring the safety and quality of construction.The main research work was as follows:(1)The SAP2000 software was used to check the process of truss system,and the force of truss slip process was calculated and analyzed from the calculation of displacement,stress and internal force of cumulative slip of truss.According to the stress and displacement analysis of the first to fifteenth slip element,the maximum stress ratio was 0.5,and the maximum deflection was 39.5 mm.The horizontal displacement was less than 5 mm,and the maximum deformation of the tension support was 6 mm upward,and the component needed not be replaced or reinforced.There was a deep excavation under the long-span roof.The stability of the slope around the deep excavation was analyzed and checked by Swedish slice method in the form of natural sloping.Under natural conditions,the safety factor of variable slope calculated by plane model was 1.055(Bishop Method),and the slope was basically stable.Under top loading condition,the safety factor calculated by plane model was 1.004(Bishop Method),which was in an unstable state.It was suggested that necessary reinforcement measures should be taken.(2)The main structure of the steel structure was 57.4m,and the span of the structure was relatively large.Underneath the main roof structure was a deep excavation.Due to the large span across the part of the grave way,steel structure construction was carried out in two construction sections from the site starting position.Each construction section was extended from west to east,and the structure was assembled into pieces by ground frame and subdivided into blocks by high-altitude frame.The construction method of cumulative slip was adopted to assemble the slider on the fixed tire rack,and the cumulative slip was completed after completion,thus reducing the high altitude mass operation.This paper solved the problem of difficult construction of the entire tomb chamber,and prepared for better protection of cultural relics.(3)The steel column of the frame structure of this project adopted double plates,and the roof system was a space pipe truss structure.Therefore,the accuracy and elevation control of steel column hoisting,sheet truss assembling,arch lifting,block assembling,truss sliding were relatively strict,especially for the construction of steel structure.The measurement of the project should follow the principle of global to local,and the total station should be used for measurement and control.Firstly,the elevation and specific position of the control points were obtained by theoretical calculation.According to the general arrangement of truss structure along the axis,the control points are laid on the steel column with the midline as the observation datum point.Through the study of the sliding construction technology of the large-span steel structure engineering of this project,we can better understand the construction sliding technology of the large-span steel structure engineering.At the same time,the understanding of slip technology in construction of structural engineering had certain reference and reference significance for similar large-span steel structure engineering construction in the future. |
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