System Reliability Of The Space Frame Of Radial Hydraulic Steel Gate

As a water-retaining structure,the steel arch-gate is widely used in water conservancy and hydropower engineering because it has many advantages such as few of embedded parts,water flow smooth,little switching power,flexible operation and so on.It is very important to ensure its safety and reliable operation.Therefore,many researchers use reliability theory to evaluate their safety.However,as a complex space structure,how to carry out an effective and accurate safety assessment based on reliability theory is particularly important to steel arch-gate.Accordingly,it is necessary that a research on the trend of the reliability of hydraulic steel gate and layout of the main frame structures should be carried out.This paper studies the system reliability of the main space frame structure of steel arch-gate.The main research work and results are as follows:Firstly,because the calculation method is restricted,the reliability analysis is for a major component such as beam and arm when researcher assessed the safety of steel arch-gate by system reliability theory.But it is difficulty to accurately evaluate the safety of main load-born structures with separated calculation.Therefore,this paper combines stochastic finite element method and system reliability theory to put forward a calculation method of system reliability considering the three-dimensional space structure effect,structure nonlinear characteristics and the correlation between failure modes in order to effectively and accurately evaluate the safety of steel arch-gate main space frame structure.Secondly,by the proposed system reliability calculation method,the main space frame structure of a traditional V shape arms steel arch-gate and a new Y shape arms steel arch-gate are computed to get the safety in form of reliability index in the state of ultimate bearing capacity and specification codes.And based on the calculation results,the safety and reliability of the two are compared and analyzed.Research shows as follows:Firstly,the proposed system reliability calculation method can calculate the reliability index of the main space frame structure in the state of ultimate bearing capacity under the standard and specification codes.And this method has simple and practical characteristics in the process of calculation of system reliability.Secondly,for the main beam in the main space frame,the system reliability index of V shape arms main space frame structure is 9.429 in the state of ultimate bearing capacity and3.834 in specification standards and the index of Y shape arms main space frame structure is9.277 and 3.383.The reliability index of V shape arms is larger than Y.But both of the target reliability indexes are far greater than the hydraulic structure reliability design codes(?_t).It shows that the main space frame designed according to the current code has a high level of reliability in the state of ultimate bearing capacity standard.Thirdly,for the main girder in the main space frame,the system reliability index of V shape arms main space frame structure is 9.489 in the state of ultimate bearing capacity and3.521 in specification standards and the index of Y shape arms main space frame structure is10.052 and 3.835.It shows that the reliability index of Y shape arms is larger than V when used the main girder frame structure.Furthermore,the Y shape arms used in steel arch-gate is feasible from the perspective of reliability index.