ABSTRACT
The additional construction procedure is also straight forward and can be synchronized with the general construction procedure so that no extra construction period is required. Table 1 shows the general construction sequence of the TPSM. First, the steel girders are erected, ready for casting of the deck concrete (Stage 1). Then the heating plates are attached to the lower flanges of the predetermined heating regions before the deck concrete is poured. As a result of heating, the lower part of the girder becomes hotter than the upper part, forming a temperature gradient in a heated section, which causes downward deflection at the midspan of the steel girder (Stage 2). During the curing
process of the deck concrete, the temperature gradient is maintained at a predetermined level, which can be achieved without difficulty by using an automatic controller (Stage 3). The heating plates are removed after the deck concrete is cured to a proper strength, which may require 3 to 7 days depending on the type of concrete and its long-term behavioral characteristics. After the girders are cooled down to the ambient temperature, the restoring force of the deformed steel girder induces initial stresses in the concrete deck (Stage 4). Simple equipment and construction procedure will allow considerable reduction in both initial construction cost and the lifetime cost.
