Analysis and tests of bonded insulated rail joints subjected to vertical wheel loads

In traditional railroad tracks, joint bars are being used to connect the en ds of adjoining rails. Because the vertical bending stiffness of two bars i s generally much lower than of the rails, the passing wheels generate large r deflections in the joint region. This in turn leads to larger wheel force s caused by the dynamics of the passing vehicles and to accelerated track d eterioration. In recent decades these expansion joints are being eliminated by the introduction of the continuously welded rails (CWRs). However, the retention of the automatic block signaling system created the need for elec trically insulated joints which utilize joint bars. A shortcoming of many o f the presently used insulated joints is that the bending stiffness of the insulated joints bars is even smaller than of the non-insulated bars that a re being eliminated. There are very few published analyses of joints in tra ck; especially of insulated joints. The purpose of this paper is to contrib ute to a better understanding of the mechanics of rail joints. At first an analysis is presented for the joint tests to;be conducted. Then a test prog ram is described that utilizes actual bonded joints. The obtained test resu lts are then compared with the corresponding analytical results. The agreem ent is good. This confirms the validity of the assumed joint model and of t he presented analysis. The paper concludes by analyzing the effect of a rai l joints in a CWR track caused by a vertical wheel load. (C) 1999 Elsevier Science Ltd. All rights reserved.