IV. BRIDGE ENGINEERING

B. ON GOING PROJECTS
8. Distress Diagnostics, Performance Evaluation and Bridge Management System for Concrete Bridges. (A collaborative project with DST, New Delhi)
Date of Start

March 2004
Central Road Research Institute, New Delhi (R)

 

Scope and Objectives

To develop a suitable technology in terms of methodologies/algorithms (for development of software) and necessary hardware (instruments/techniques) applicable to different concrete highway bridges in the country, for Bridge Management System.

 
Methodology

Concrete bridges are prone to distress due to deficient design, detailing and construction practices, exposure to aggressive environmental condition, overloading etc. Identification of causes of distress is an essential step prior to rehabilitation and distress of bridges. Being a techno economical issue, this can be easily tackled by implementing a Bridge Distress Diagnostic System by the owners or maintenance departments of bridges in our country.

A comprehensive methodology has been adopted to evolve the distress diagnostics and the serviceability performance of the RC T-girder bridge superstructure bridge, which could be a module of bridge management system for a highways network. The

Thorough visual inspection - to help creation of data bank

Nondestructive testing to arrive at causes of distress both in terms of extent and qualitatively and

Rating of the bridge and Estimation of remaining life (residual strength).

Development confines to one number of bridges of type T-beam girder which is most commonly employed on highways in India.

 
Present Status and Progress

After the preliminary design of the bridge Inspection system, a detailed design of the system including the joints has been undertaken in collaboration with MERADO, Chandigarh and CMERI, Durgapur.

A Bridge Distress Diagnostic System has been developed to identify the distresses in RC T-girder Bridge superstructure with the help of analysis of inspection data and subsequent confirmation of cause of deterioration in bridge elements with results/data of appropriate non-destructive and destructive tests. Interactive software has been developed In Visual Basic as front end and the SQL as back end for storage of database and Crystal software for report generation.

The Software comprises two main modules namely Bridge Inventory Module and Bridge Inspection Module.

The Bridge Inventory Module is capable of taking data inputs related to bridge such as administrative data, general data, technical data, geometric Data, hydraulic data for bridge over rivers, geotechnical data, environmental exposure conditions and photographs.

The Bridge Inspection Module in turn calls eight sub modules pertaining to elements such as WEARING SURFACE, DECK SLAB, T-GIRDER, APPROACH SLAB, PARAPET/ RAILINGS/CRASH BARRIER, FOOT PATH ,BEARING and EXPANSION JOINT


The coding of these modules has been carried out based on the checklist of data to be collected during the inspection of the bridge superstructure components. The inspection of bridges is classified as routine inspection, detailed inspection and special investigations after natural calamities such as flood, cyclone, earthquake, land slide etc.

While preparing the checklist of data to be collected during the inspection of a bridge, apart from relevant literature the prevalent IRC codes and special guidelines have been referred.

Some of the above modules in turn calls the relevant subroutine from the list of eighteen subroutines such as POT HOLES, POP-OUTS, WHEEL TRACK RUTTING, WEAR AND ABRASION, SCALING, SPALLING, HONEY COMBING, DELAMINATION, UPV-Soundness, UPV- Crack width, UPV-Delamination, CONCRETE RESISTIVITY TEST, CORROSION OF STEEL, OCP/HCP, -CARBONATION, CRACKING, RCT etc.

These subroutines are capable of taking the data obtained by inspection and analyse the severity of damage. Depending on the severity of damage decision on further investigations required are specified by the software. The appropriate NDT/ DT tests included in the program are selected such that they are simple, readily available in our country, economical and give reliable results. These tests have been selected based on their application in some of the bridges rehabilitated in India.

Also, for the distress diagnostics in bridges, a dedicated BDI system has been procured from M/S Bridge Diagnostics Inc. USA. It has been used to evaluate the performance of the RC slab and T- beam girder bridge.
 
Significance/Utilization Potential
The software developed being unique in nature, after incorporating other types of bridges would be very useful in distress diagnostics, rehabilitation and management of highway bridges in India. BDI system will be very useful in performance evaluation of bridges quickly with least interruption to traffic.
 
Limitations
The software developed addresses the distress in RC – T girder superstructure only.
 
Reports/Publications
1. G.K. Sahu, R.K. Garg, “Field test on Lyons Bridge (USA) and Slab Bridge at Hapur (India) using Structural Testing System, Report No: CRRI/BAS/CLP 4413-STS II, December, 2005.

2 . R.K. Garg, Ram Kumar (2006), “Strength Assessment of Existing Bridges for Bridge Management System”, National Conferences on Advances in Bridge Engineering, IIT Roorkee.