Research On Reliability Of Spatial Beam String Structure Based On Response Surface Method

As composed with plane beam string structures, the mechanical characters of spatial beam string structure is similar with the plane structures in many aspects. Modern design theory and method is based on the theory of reliability, spatial beam string structure is a new type of structure style with its unique characteristics, SFEM is an efficient method to be applied into analysis of reliability.With the project of steel roof, reliability of structure under several interactional failure modes is studied, as well as the sensitivity of reliability index.With the combination of response surface method to reconstruct performance function and SFEM simulation, the ratio of construction resistance is defined as random output parameter to fit the state function and to calculate probability of failure. New state function is simulated through SFEM sampling based on the sampling center modified by linear interpolation.Research on spatial beam string structure considering several failure mode shows that, generally speaking, probability of failure under strength failure mode is rather low, the case of displacement control is highest, reliability of stability under half span load is a litter higher then under full span. The cable pre-stress of the spatial beam string structure will influence the displacement of structure in both initial and working state, but the stiffness of structure will not be effectted. As a result, for the mastering displacement failing mode, the cable pre-stress will make notable influence to the reliability index when controlling displacement under working state, while the index will not be effected when controlling increment of displacement. Consider several failure modes as a series system. Ignoring modes with very low failure probability will make no difference to system reliability, whereas modes with adjacent failure probability can't be ignored, through correlation coefficient matrix. A probability-weighing approach method foe calculating the reliability of structural system is worked out by taking into account of correlation among various possible failure mechanism in the system, as well as the effect of a single mechanism failure on the failure of the whole system.Research on reliability's sensitivity of spatial beam string structure shows that the most sensitive and insensitive factor of reliability are different considering different failure modes, take insensitive variable as constant can reduce sampling number and improve efficiency. Ignoring the...