Research On The Nonlinear Instability Of The Thin-wall Hollow Pier

With the construction of the vehicular bridges in mountain area,more and more bridges which cross over deep valley generate.The land form in mountain area is various,with deep ditches and steep slopes,therefore,many piers are requested to be built in the high form.Inorder to reduce the volume of mason,save the consumption of materials,or to reduce the self-load of piers,make sure they have relatively low inertia forces in earthquake,low down the stress acting on the basement,the pier shaft are often built in a hollow form.This type of pier is called hollow pier.Thin-wall hollow pier is a form of hollow piers.Since this type pier has a relatively low stiffness,it is allowed that the pier is capable of deflecting sideways larger,guaranteeing the stability of the bridge,while possible to effectively save materials and reduce their self-load.In recent years,as the preferred form in the piers of continuous rigid frame bridges,thin-wall hollow pier is widely used. Thin-wall hollow pier has been used in many bridge structural engineering,so as its stability behavior should be payed high attention to in engineering circles.The problem of stability has equal significance to that of strength of material.Since long span bridges often use high-strength materials and thin-wall structure, the problem of stability became more important.For the bar or plate in compression,the structure may be instable overally or locally,if the treatment in technique is not appropriate.This article focuses on the investigation of the effect that the slenderness ratio,aspect ratio of cross section and ratio of thickness have on the overall and local stability of the thin-wall hollow pier with single cell box girger.For each facter,which is relative to the stability of thin-wall hollow pier,mentioned above,the critical load for linear instability and the ultimate load,or collapse load for non-linear instability of the thin-wall hollow piers with various of scale will be solved,based upon two sets of completely distinct theories,the theory of stability for compression bar and the theory of stability for compression plate.With the critical load and the ultimate load calculated,we should obtain the safety coefficient for two types of stability.Furthermore we will analyse,under two sets of theories mentioned before,the rule that the stability safety coefficient of the thin-wall hollow pier varies with the slenderness ratio,aspect ratio of the cross section and ratio of thickness.Finally,the respective realm for application of the theory of stability for compression bar and the theory of stability for compression plate will be determined,owing to the foregoing results.