Construction Mechanic Analysis And Control Study Of Large-span Steel Roof Of Yongqiang Airport

Large-span steel structure is the main construction form of public building structure.It is mainly used in large-span space structure in public buildings.It has the advantages of beautiful,light weight and a simple style of force.As a plenty of large-span spatial structure come out,which lead to the study of construction mechanics,construction force is a synthesis of a series of mechanical problems,which is different from the design force,Its analysis process is dynamic change,its load also has time-varying characteristics,Its analysis process involves different analysis theories,different modeling processes,different construction conditions and the influence of the process,different software platform,so it is necessary practical research si in this time.This paper based on the T2 terminal of Yongqiang airport of Wenzhou,Zhejiang,combined the advanced calculation theory,calculation method and the software analysis platform now,go on a analysis and study to the sunroof of the terminal,put forward to feasible construction control method and construction suggestions.Its main is as follows:1.Summary the main construction methods now in truss structure,in which we abstract the construction mechanic problems.Combined the style of truss structure,the nonlinear finite theory of bar structure is listed,as well as the mathematical calculation methods.2.The modeling method of the pre-stressed stringed beams in ANSYS are detail introduced,which contain how to deal with boundary condition,the choice of element in ANSYS and the setting of parameter in software which used to accelerate the convergence.According to the construction plan of the pre-stressed stringed beams in the airport,there are three methods to be choosed.The different construction methods are modeling in ANSYS used reversed methods,which are totaling different from the construction order.The first pre-stress loss rate is used as the index to compared the three pulling method,according to the result in the software show that the rate pulling from two sides to the middle is the least.3.In the process of modeling,two methods are introduced to simulate the pre-stress in the bar,one is the cooling method and the other one is the initial strain method,a comparison was done to these two method.Another problem is the convergence method,degradation compensation method and hybrid method are compared to model the spatial pre-stressed steel structure.The result show that degradation compensation method is suitable to simulate single stringed beam under a bigger error,but hybrid method is suitable to simulate under a lower error.To certificated space structure,the divergence is easy to occur if we model with hybrid method,but degradation compensation method is easy to convergence under bigger error,such as 5%,two methods are not suitable to simulate certificated space structure.We use all the method above to simulate the stringed structure in the airport,we set a goal given by the design apartment if all the beams are pulled finally.According to the results,we put forward a passive tension method which is different from the traditional method,which pull the steel bar by the equipment.Two index are applied in the passive tension method,one is force in the first stage,the other is displacement in the second stage.We adopt the passive tension method to the airport,through the data getting from the structure,we found that the method is feasibility in actual engineering.4.This paper explain the whole lifting technology in large span steel structure,in modeling,how to deal with boundary conditions,how to deal with the force,how to choose the element,how to show the process of construction are all important to accuracy simulate the structure.the variable superposition method are used to simulate the whole stage.As un-synchronized lifting are exist in actual lifting,we discuss this by lifting discontinuous points or adjacent points in the software.Based on this we put forward to unfavorable load combination and measures of reducing the un-synchronized lifting.According to the calculation,we replace the bars which exceed the value we set in advance.All the work ensure the safety of the engineering.