| As the most advanced core construction equipment for super high-rise buildings,the integral steel platform has the advantages of simple operation,high load-bearing capacity and high safety,and plays a vital role in the construction of cores.However,due to its short history and imperfect theoretical system,the analysis of its force performance is an important theoretical guidance and practical application value to ensure its safe and stable operation.Based on a super high-rise steel platform project in Xi’an and Changsha,this project aims to analyse the stress performance of the steel platform under different working conditions and to monitor the stress and strain during the construction process,and to analyse the time-varying reliability of the core during the construction of the steel platform,taking into account the high-strength concrete material at the support and the time-varying and random nature of the reaction load.The main research work is as follows:(1)Relying on the steel platform project between Yunsong in Xi’an Qujiang New Area,the static analysis of the overall steel platform was carried out using Midas Gen software to explore the stress,displacement,stability and stress ratio changes of the truss and main column under the four working conditions of the platform in the construction,jacking,self-climbing and high wind stopping stages,and the calculation results and the site data were in comparative agreement.The analysis results show that the overall steel platform of the project meets the requirements of the code in terms of stress,displacement and stability,and the structure has the corresponding safety.(2)Relying on the data of two steel platform projects,namely Yunsong Room in Xi’an Qujiang New Area and Changsha Greenland V Island Star City Light Tower,the analysis of stress,deformation,stability and ultimate bearing capacity of the core shear wall in the standard floor construction under various construction conditions of the steel platform was completed,and a sensitivity analysis of the core shear wall during the construction of the steel platform was conducted.The study shows that the following three aspects should be considered in the design of the steel platform construction without affecting the construction demand: avoiding single piece walls and thin walls as far as possible in the leg arrangement,reducing the steel platform stacking load on the single piece walls,increasing the horizontal support at the corresponding position if necessary,in addition to ensuring dynamic stability as far as possible during the steel platform self-climbing and jacking process to avoid adverse effects of load surge on the walls.(3)Determine the random variables for the time-varying reliability analysis of the core shear wall,use LHS to sample the random variables,establish the limit state response surface through Kriging model,and carry out time-varying reliability analysis of the core shear wall structure system based on time-varying reliability theory for two steel platform projects in Xi’an and Changsha.The study shows that the wall of the attached steel platform may fail in the self-climbing and pre-topping stages,especially the probability of failure in the self-climbing stage is higher;the wall of the pivot less steel platform may fail in the self-climbing and topping stages,especially the probability of failure in the topping stage is higher.(4)By analysing the coefficient of variation of reaction load and the probability of failure of the system and reliability index of the two steel platform projects in the self-climbing and jacking stages,when the coefficient of variation of reaction load of steel platform is taken as 0.3,the reliability calculation result of shear wall is safer. |
