MASTERING MOVEMENT: SEISMIC PROTECTION AT PAKSEY

Seismic protection was an important consideration to the design of the new Lalon Shah Bridge in Bangladesh. The 1,8 km long highway bridge consists of 15 spans of precast segmental construction supported on 16 concrete piers and it carries two lanes of traffic in each direction. Some of the largest shock transmission units ever manufactured for a bridge have been installed on the Lalon Shah Bridge. The pier attachment bracket and its anchors were designed to be cast into the concrete after the installation of the pins, so that adjustments could be made easily. Life expectancy of each unit is a minimum of 50 years; the medium in the cylinder is a silicone putty compound that can not leak past the hydraulic seals, and these seals have been tested for hundreds of thousands of cycles without wear. Since each unit will experience only a few cycles per year, the life expectancy of the design is at least fifty years.