Structural Analysis: The Bridge Model Of The Bridge

The bridge model is a three span bridge with 60, 80 and 60. The carriageway is 7 m wide by 1.0 m wide sidewalks along each position. There are in situ diaphragm abutments and pier. The superstructure is built integral with the base. The foundations of the bridge are precast concrete piles with in-situ pile-caps. To avoid unnecessary reactions resulting from thermal expansion of the platform, the abutments are taken as small batteries and flexible enough. Although not enough to fill the back foot diaphragms to resist forces of longitudinal acceleration and braking.

The bridge, with a continuous three-span deck: 60 m - 80 m - 60 m, has a total length of 200 m. The deck has a constant depth along the whole length and its longitudinal axis is straight and horizontal.

The total slab width is

Checking the opening of cracks and stress limits, will not be required for concrete elements. When the tensile flexural stress exceeds the effective tensile strength fcteff, then a check for pre-stressed concrete is required. This should normally occur when sections do not have tendons near the tension face or there is no exposure to chlorides, so decompression doesn’t have to be checked. The analysis using uncracked section will be done in sections controlled for decompression and have tendons near the surface tension. As the cracked section analysis is done by computer, it solves the complexity of the calculations. However, this does not mean that pre-stressed cannot be calculated directly from a set of equations as with crack width checks for RC.

The transfer will govern the design, with decompression in service. It was found that eliminating small detachment of the tendons by using reinforcement in the top of the beam, resulted in savings. Another approach using strands near the top, but low enough that decompression requirement is achieved with a transfer, would limit the top stress