The expansion joints of the 1915Çanakkale Bridge

Abstract

<p>The recently opened 1915Çanakkale bridge 300 km south-east of Istanbul has a main span of over two kilometres and a total length of 4,608 m.</p><p>Based on the bridge kinematics, complex expansion joints at both main deck ends with movements of up to 2800 mm, low noise emission and highest durability were required.</p><p>In addition, the approach bridges to the main bridge, which are seismically isolated, requested large transversal movements.</p><p>So-called modular swivel joist expansion joints allow six degrees of freedom: displacements transverse, longitudinal and vertical to the direction of traffic as well as any kind of rotations can be compensated, to address the specific needs of a suspension bridge located in a highly seismic region. The expansion joint structure, consisting of bars supporting the lamellas, features a new low-friction, almost wear-free guiding system with a next generation of sliding material. This prevents restraints, provides a superior smoothly controlled movement mechanism, and increases the service life to at least 50 years.</p><p>Particularly, an approved sliding material (modified UHMWPE, pre-loaded and equipped with greased dimples within the moving components, which has been successfully applied for two decades in the bridge bearings, grants proper function for a certified accumulated travel path of 50+ kilometres even combined with high seismic displacement velocities. A more precise prismatic guide mechanism was developed to achieve a permanent contact between all relevant sliding elements.</p><p>In this way both the bridge bearings and the expansion joints systems can reach the same certified nominal life and durability while resisting major earthquakes without damage.</p><p>The expansion joints were additionally equipped on their surface with welded rhombic steel plates to remarkably reduce the noise, increase the driving comfort and assure a durable anti-skid resistant across the overpassing surface. Also, welded instead of bolted applications within the construction enhance fatigue-proof and durable service lifetime of the applied expansion joints.</p><p>The joints of the approach bridges were designed with special rhombic steel plates that allow also large transversal movements.</p>