Safety Control In The Whole Process Of Long-span Cable Membrane Steel Truss Structure

Based on the Yueyang Sanhe Airport,the structural shape finding,wind-induced vibration response,identification and monitoring of key components and safety control technology in long-span cable-membrane-steel trusses are mainly studied in this dissertation The thesis included several contents as follows:(1)This thesis introduces evaluation method and its application using ANSYS in the form-finding method of finite element and parametric application for APDL in ANSYS,and which are used in initial form analysis for the large and complex of cable membrane structure.Initial form model of large and complex cable membrane structure is obtained when the influence of analysis of supporting structure through discrete method and fractional step method by course method are considered,and this study laies a foundation for the analysis response of the wind load(2)A distribution of wind load characteristics on the surface of this cable-membrane roof is studied,which bases on the wind tunnel test of large-span ridge-type scale model by a 1:100 rigid model.It is pointed out that the corner area should be strengthened in the design,in order to avoid the wind overload causing the local damage in the angle area under the worst wind direction load,and the recommended value of regional shape coefficient is given by the pressure measurement test of rigid model and the analysis of wind-induced response.In this paper,the contact angle of wind has been gotten when the most unfavorable equivalent wind load and as the wind-induced response appear,and the position of the most unfavorable load is also briefly analyzed in this paper with the increase of the span of cable-membrane structure.The wind pressure coefficient of corner area will be significantly larger than the value of wind pressure coefficient in the specification(3)The weak parts of the structure and the chain reaction characteristics caused by the local structural failure are analyzed,and the key members of long-span cable membrane-steel are obtained through the sensitivity analysis method,relying on the roof structure of Yueyang Sanhe Airport.The results show that the back cables on both sides and suspension cable are the key members in the system of cable based the coefficient of importance.A large change in structural response will be caused when the lower chords of the middle of truss girder and the mast fail,and thus they can be determined as key members.A reference is provided for the monitoring of key components or areas during construction and subsequent operation,as well as for the anti-continuous collapse design of similar long-span spatial structures.(4)The safety control of the whole process of cable-membrane structure construction are realized,and the cable tension during the process of upper and lower suspension cables,and the cable force during intimae construction and installation,and the stress and deformation of components are effectively monitored during the installation construction process of steel structure,based on chain reaction characteristics and the key components,weak parts and local structural failure determined by the research and determination of resistance to continuous collapse.The analysis results show that the theoretical calculation of cable force in each construction stage is basically consistent with design,the maximum difference is fifty-six kN(1.386%),the vertical cumulative maximum displacement of high mast is 26mm,and the vertical cumulative maximum displacement of low mast is 25 mm.The measured data of all working conditions are compared with the theoretical results,which are within a reasonable range,and the bearing capacity and safety performance of the structure can meet the design requirements.(5)A corresponding finite element model is established,and the static and dynamic responses of the structure under various load conditions are analyzed according to the cable membrane structure of Yueyang Sanhe Airport terminal.Secondly,A requirements of the monitoring system and the overall structure are studied,and the concrete implementing scheme of the structural health monitoring system is designed which based on the results of finite element analysis,providing a complete solution covering structure and load perception such as collection,transmission,storage,processing,analysis,evaluation and early warning.The proposed health monitoring system architecture has been successfully applied to the monitoring of long-span cable-membrane structure stations in Yueyang Airport,and the synchronous acquisition of grating fiber and speed sensor signals has been innovatively realized.The successful implementation and operation of the structural health monitoring system will provide guarantee and basis for ensuring the normal and safe service of the structure and the smooth development of the second phase of the terminal project.(6)A finite element model considering the construction deviation for discussing the influence of joint deviation and cable force uncertainty on the safety performance of the structure in the construction process is established,and the ultimate bearing capacity of the structural model without considering the construction deviation is compared with that considered.The ultimate bearing capacity factors are 2.22 and 2.70,respectively.The reliability index of the structure considering the uncertainty of cable force calculated by the multi-response surface method is 6.76,which is at a high safety level.The reliability analysis shows that the uncertainty of cable force has a great influence on the reliability of the structure,and the uncertainty of cable force on the upper chord cable and the back cable force on the land side have the greatest influence on the reliability,and special attention should be paid to it in the construction and operation stages.