Methods Of Determining The Equivalent Support Stiffness Of Brace Fram For Deep Excavation

At present, in usual practice of design of retaining structures for deep excavation is plane finite element method .But the equivalent support stiffness of brace structure is determined by experience, therefore, that will bring mistake for the design. So, it's necessary to find a way to compute the equivalent support stiffness reasonably. In this paper, the deformation behaviour of brace structure is systematically studied. The main contents in this paper are as follows:1. Study the deformation and internal loading of the brace structure under uniform loading, and propose tow methods of computing the equivalent support stiffness under uniform loading.2.Study the deformation and internal loading of the brace under local loading, and Preliminarily propose a methods of computing the equivalent support stiffness under local loading.3.Preliminarily discuss a methods of computing the equivalent support stiffness under uniform loading and local loading.4.Corresponding finite element analysis programs of these methods are developed.5.Analyse the distribution of equivalent support stiffness on brace structure, and study the influence of internal brace on distribution of equivalent support stiffness.Some conclusions obtained are as follows:1.Propose tow methods of computing the equivalent support stiffness under uniform loading. The results from these tow methods are nearly the same.2.The equivalent support stiffness under uniform loading is highly affected by brace type. Strengthening one part of the brace can enhance the equivalent support stiffness of this part, but also can weaken other parts'. Conversely, weakening the stiffness of overly strength part can enhance other weak parts. It's the best way of enhancing the bracing-system's stiffness to choose a reasonable brace system.3.Preliminarily propose a methods of computing the equivalent support stiffness under local loading. Rigid body's rotation and plane move under local...