| In recent years,due to the prestressed steel structure advantages of reasonable stress,high rigidity,light weight,good seismic performance,short construction period,economic and beauty,its has been widely used.Some prestressed steel structure engineering in our country has serviced for nearly 30 years.The existing health status of the structure,the loss and variation of the prestress value,the degree of cable maintenance,the degree of structural damage and so on are mostly in the absence of monitoring and management.The residual life expectancy of the structure,safety assessment,repair and reinforcement,prestress loss compensation is very unfavorable.Therefore,it is very urgent to conduct systematic research on the safety assessment technology of prestressed steel structure,to take effective measures for the completed structure to conduct safety status assessment and reliability performance analysis,this has become a major issue facing the current structure of prestressed space in China and this is also a hot issue in the world.This subject is based on Beijing Science and Technology Rising Topic "Key Technology Research and System Development for Prestressed Steel Structure Safety Assessment" and takes the spoke truss structure as the research object,carries on the model test for the static loading and different damage conditions of the prestressed steel structure in service,Mainly include the following points:(1)Completeing self-weight load,a quarter of live load,semispan live load,three-fourths live load,full-span live load test;(2)Completeing length error and random error test for cable components separately;(3)Testing under the influence of applied temperature effect;(4)Completeing pre-stress loss of cable test.According to the theoretical model,the revised model obtained by three-dimensional scanning after the model is stretched and molded,the comparative analysis of the experimental model data,the influence and the sensitive components of the spoke damage truss structure with different damage conditions are obtained.Based on the reliability theory and ANSYS analysis software,the key technologies of the safety assessment of prestressed steel structure are studied about three damage conditions for loss of length,temperature,and prestress.Based on the response surface method,the corresponding calculation program is compiled,and the prestressing force The failure mechanism of steel structure,determine the damage limits under different damage conditions,calculate the sensitivity of each parameter,give the limit and impact of the error,damage and defects of the cable and other key components,Eventually determine the input variable material properties and applying prestressed input variables to output structure mechanics indexes such as the sensitivity of value and its change trend,summarizes the influence of various uncertainty damage on structure safety,to take the lasso prestressed structure in practical engineering of security service guarantee. |
