Expert system technology has been successfully applied to bridge design. ES-PDLB is an expert system for the preliminary design of long-span bridges. It can simulate design projects including bridge type, span layout, outline dimensions of cross-sections and construction method, after given the conditions of topography, geology and hydrology at the site of a bridge toe built, and traffic requirement on and under the bridge. The detailed description of this system will be presented in this paper.

the present paper outlines the large deflection elasto-plastic analytical results for thin square plates with initial imperfections subjected to in-plane loads. The elasto-plastic rigidities are calculated using a rigorous multi-layer approach. The governing equations are solved in an incremental form by applying dynamic relaxation method (DRM) as proposed by the author M, 21. based on the computational results, the paper discusses the plastici zation history of the panels.

The present paper very briefly outlines the so-called Dynamic Relaxation Method (DRM)which is found to be suitable in analysis of both geometrical and material nonlinearities using personal computers, and discuss an approach recently at SWJT for the automatic selection of interaction parameters in the DRM. The solution of a nonlinear truss-spring, the analysis of plate bending problems with large deflections under transverse loading, and the calculation of the ultimate load of plates under an in-plane load, using DRM with personal computers, are described.

本文对动态松弛法提出一优化参数自动选择程序，使解题所用机时只是有限元法或有限差分法的1/8至1/10。这法可用以推算板在面外荷载或面内荷载作用下的极限承载力。对于面内荷载是以下五种情况：纯压，纯剪，纯弯，剪和压，剪和弯，经用此法研究了极限承载力和下列参数间的关系：板的宽厚比，板的初始几何缺陷，板的残余应力，边界条件。以所推算的结果和英国的成果（理论值和试验值）及英国桥梁规范BS5400的规则相比，它们符合得使人满意。