DESIGN ASPECTS OF THE PRECAST PRETENSIONED U-GIRDER BRIDGE FOR METRO RAPID TRANSIT SYSTEM

Abstract

Bridges are the utmost important part of human life and their requirements are increasing day by day in various aspects. Safety of life is the prime consideration for design and construction of bridges. For example, as in the field of tall buildings, different structural systems are required for different heights. Similarly, in the field of bridge engineering special type of bridge is required for depending upon the span length. Slab type, hollow slabs and RCC Tbeam bridges are preferred for smaller spans while box and truss type bridges are preferred for longer spans. This is due to their increased moment of inertia. But due to the increased depth of these structural systems overall height of the bridge is also increased to maintain the vertical clearance below deck slab. Thus, a separate study and comparison of various bridge types are required based on their application so as to make use of the most efficient structural system. This project report is prepared by studying the various design aspects of U-Girder bridges applicable for Metro Rapid Transit System (MRTS). The main advantage of the U-Girder bridges are reduction in the height, weight and time of construction of the superstructure so as to decrease the overall cost of the project. 2m depth of segmental box type of bridge is replaced by 250mm (approx.) thick deck slab of U-Girder, reducing the height of every pier by 1.75m. Longitudinal analysis is carried out to calculate the amount of prestressing required and transverse analysis is carried out to calculate the amount of reinforcement required. The section for U – Girder is taken from the standard drawings of DMRC for U-Girders.