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In order to study the mechanical properties of defect-free thin walled elbows (TWE), and evaluate impacts of the intermediate principal stress effect, tension/compression ratio, and strain-hardening of materials into logical consideration, this research, in the framework of finite deformation theory, derived the computational formula of burst pressure for defect-free TWE according to unified strength theory (UST). In addition, influences of various factors on burst pressure were analyzed, which include strength disparity (SD) effect of materials, intermediate principal stress, curvature influence coefficient, strain-hardening exponent, yield to tensile (Y/T) and thickness/radius ratio. The results show that the greater the tension/compression ratio is, the higher the burst pressure is. The influence of the SD effect of materials is more obvious with the increase of elbow curvature and intermediate principal stress. The intermediate principal stress effect can bring the self-bearing capacities and strength potential of materials into a full play, which can achieve certain economic benefits for projects. Moreover, the burst pressure of defect-free TWE increases with the growth of yield ratio and thickness/radius ratio, while decreases with the rise of curvature influence coefficient and strain-hardening exponent. It is also concluded that the Tresca-based and Mohr–Coulomb-based solutions of TWE are the lower bounds of the burst pressure, the twin shear stress (TSS)-based solution is the upper bound of the burst pressure, and the solutions based on the other yield criteria are between the above two. The unified solution in this paper is suitable for all kinds of isotropous materials which have the SD effect and intermediate principal stress effect. As the deduced formula has unified various burst pressure expressions proposed on the basis of different yield criteria for elbows of any curvature (including straight pipelines), and has established the quantitative relationships among them, its applicability is broader. Therefore, the unified solution is of great significance in security design and integrity assessment of defect-free TWE.

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In order to improve the management and control level of bridge construction and understand the real-time dynamics of bridge construction in real time, a set of cloud 3D visualization information management and control system is created based on the Internet platform. In view of the characteristics of high precision and great difficulty in the construction control of corrugated steel webs bridge, a set of construction control and control software based on B/S (browser/server) architecture is developed to help managers know the site structure state more intuitionistic and improve the efficiency of construction control and control. The system deeply integrates the two-dimensional plane information with the three-dimensional entity, and realizes the three-dimensional display of information flow by highly restoring the real bridge construction state in the three-dimensional scene. The results show that the system can assist the management personnel to carry out construction management and improve the engineering efficiency through linear prediction. The system can realize the dynamic demonstration of the long span CSW-PC continuous rigid frame bridge 3D model and the graphical display of the construction measurement and control data and progress information.

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