Stable Bearing Capacity Analysis Of Some Kind Of Simple Constructed Shallow-arch Roof Truss

The application of steel tube truss arch is becoming more and more popular in recent years, especially the truss in shallow arch type has been widely used in depot, small factory, and public facility, so the stability of the steel shallow arch truss becomes more important. Combining with the inspection date of some un-regularly designed steel shallow arch truss, this paper made the research of whole stability and defect affection about the simple constructed roof truss with unfamiliar weak stiffness.Base on the analysis of the spot inspection data, weak stiffness of arch ring is the most important character of the simple constructed shallow arch truss, and it makes the truss easier to lose stability, so this paper will proceed with the stability analysis of the roof truss to make the research. The content of this research divide into three aspects as follows:①By generalizing the former stability research of the arch structure, this paper induce the buckling character of weak stiffness shallow arch truss, analyze the in-plane and out-plane stability of the shallow arch truss by using theoretical and numerical analysis to confirm the ultimate stable bearing capacity.②Analyze the disadvantage affect of defect to the bearing capacity by using numerical analysis, and find the main disadvantage factor.③Analyze the stress status under the basic combinational load effects, and get the stable security evaluation of the simple constructed shallow arch truss by consulting some reliability appraisement materials.This paper obtains the following main research results:①Due to the weak bending stiffness, the shallow arch truss appear great in-plane bending deformation and out-plane bending-torsion deformation in the nonlinear buckling analysis.②With the weak stiffness the fixed base and hinged base nearly have the same affect to the bearing capacity of the roof truss.③The lower chord near the arch springing yield first in the loading course, and after its strength failure the stress in the truss redistribute, the truss still can bear loads, but the bearing capacity after the lower chord yielded is so weak that the intensity and stiffness can not be used.④The stiffness between the chord and brace is quite different that stiffness of the joints can be ignored, and the brace can be see as axial compressive bar to analyze its stability.⑤Initial bending, corrosion and the broken of welding seam can greatly weaken the bearing capacity of the roof truss.⑥With the analysis of the stress status under the basic combinational load effects, the roof truss is very close to the ultimate state, and the safety reserve is seriously not enough, it is not suitable for the roof truss still to bearing loads.This paper studied on the whole stability and defect affects of this kind of un-regularly designed simple constructed shallow arch truss, and it afford a theoretical reference for this kind of roof truss with some referenced value in test and appraisal engineering.