ASSESSMENT TECHNICS FOR EXISTING ROAD BRIDGES

2015

Bridges play a vital role in road infrastructure networks. According to Statistics Canada, bridges and overpasses accounted for 8% of total public assets in 2007.. Ontario ranked as the third among provinces in terms of having old bridges. In 2007, Bridges in Ontario accounted for 7% of its public infrastructure, while in Alberta, bridges account for 9% of total public infrastructure. Bridge condition assessment is conducted to determine load rating capacity for bridge elements. The identification of current condition of each element provides early warning of necessary maintenance. Condition rating is performed during the inspection process. This paper provides a comparative study of current practices in bridge condition rating worldwide, with emphasis on the United States and Canada. The study includes 4 main criteria: inspection levels, inspection principles, inspection frequencies and numerical ratings for 4 provinces in North America: Alberta, Ontario, Quebec and state of Oregon and 5 countries outside North America: United Kingdom, Denmark, Portugal, Sweden and Australia. The Limitations of current practices are discussed and recommendations for improved inspection are provided. The study is expected to assist professionals and inspectors in selecting feasible method/s for effective bridge condition assessment.

Journal of Civil Engineering and Architecture, 2012

Due to the substantial role of bridges in transportation networks and in accordance with the limited funding for bridge management, remediation strategies have to be prioritised. A conservative bridge assessment will result in unnecessary actions, such as costly bridge strengthening or repairs. On the other hand, any bridge maintenance negligence and delayed actions may lead to heavy future costs or degraded assets. The accuracy of decisions developed by any manager or bridge engineer relies on the accuracy of the bridge condition assessment which emanates from visual inspection. Many bridge rating systems are based on a very subjective procedure and are associated with uncertainty and personal bias. The developing condition rating method described herein is an important step in adding more holism and objectivity to the current approaches. Structural importance and material vulnerability are the two main factors that should be considered in the evaluation of element structural index and the causal factor as the representative of age, environment, road class and inspection is implemented as a coefficient to the OSCI (overall structural condition index). The AHP (analytical hierarchy process) has been applied to evaluate the priority vector of the causal parame

2009

Condition assessment and safety verification of existing bridges and decisions as to whether posting is required currently are addressed through analysis, load testing, or a combination of methods. Bridge rating through structural analysis is by far the most common procedure for rating existing bridges. Load testing may be indicated when analysis produces an unsatisfactory result or when the analysis cannot be completed due to lack of design documentation, information, or the presence of deterioration. The current rating process is described in the American Association of State Highway and Transportation Officials (AASHTO) Manual for Bridge Evaluation, First Edition, which allows ratings to be determined through allowable stress methods (AS), load factor methods (LF), or load and resistance factor methods (LRFR), the latter of which is keyed to the new AASHTO LRFD Bridge Design Specifications, which now is required for the design of new bridges, effective October, 2007. The State of...

Engineering Sciences, 2020

Changes in properties of concrete bridges, during their usage, demand careful monitoring, registration of defects and damage, and corresponding repairs. Therefore, the serviceability mostly depends on the quality of their maintenance. Maintenance of structures is a big problem due to lack of money for repairs. Safety and functionality of concrete road bridges are of a special importance for the traffic flow continuity in different circumstances including after earthquakes, floods, as well as after vessel or vehicle impact on piers. This is why almost all countries use Bridge Management Systems (BMSs). They include the bridge inspection manuals, guidelines, report writing, bridge condition evaluation and determination of priorities (rating) for maintenance work or rehabilitation to achieve the design service life of bridges. This paper presents a comparative analysis of some documents of certain countries and associations, related to BMSs and their main components.

2011

Due to the substantial role of bridges in transportation networks and in accordance with the limited funding for bridge management, remediation strategies have to be prioritised. A conservative bridge assessment will result in unnecessary actions, such as costly bridge strengthening or repairs. On the other hand, any bridge maintenance negligence and delayed actions may lead to heavy future costs or degraded assets. The accuracy of decisions developed by any manager or bridge engineer relies on the accuracy of the bridge condition assessment which emanates from visual inspection. Many bridge rating systems are based on a very subjective procedure and are associated with uncertainty and personal bias. The developing condition rating method described herein is an important step in adding more holism and objectivity to the current approaches. Structural importance and material vulnerability are the two main factors that should be considered in the evaluation of element structural index and the causal factor as the representative of age, environment, road class and inspection is implemented as a coefficient to the overall structural index. The Analytical Hierarchy Process (AHP) has been applied to evaluate the priority vector of the causal parameters.

Strength assessment of bridges is an important activity in the Bridge Management process. Various aspects related to assessment of current strength as well as in future are discussed. Methodology suggested by IRC is also discussed with the help of a case study. The discussion would provide to adopt appropriate methodology for assessment of load carrying capacity of the bridge(s) for the purpose of Bridge Management System suitable to Indian conditions. INTRODUCTION

STRENGTH ASSESSMENT, REPAIR, STRENGTHENING AND HEALTH MONITORING OF EXISTING BRIDGES FOR OVERLOADING A METHODOLOGY AND A CASE STUDY, 2015

A systematic methodology is presented for the process of assessing and temporarily upgrading the load carrying capacity of existing bridges to carry loads heavier than their design loads. This methodology includes: analytical and experimental evaluation of the bridges; design of repair and strengthening works; and monitoring the condition of the bridges, before and after the transportation of the specified loads, using modal tests to address any damages caused by these heavy loads. A case study is presented to illustrate the application of this methodology. In this case, one segment of Cairo ring road, Egypt, was chosen for the transportation of new four units for northern Cairo power station. The new units were extremely heavier than the design load of existing twenty one bridges allocated along this segment. Different site tests were conducted in conjunction with analytical checks to help in assessing the load carrying capacity of the bridges. The existing bearings were temporarily supported by jacking up the bridges and adding temporary steel seats. Temporary supporting towers were constructed to support the bridge decks in some areas. New independent foundations were built under these towers. All cracks above 0.3 mm wide were injected. The corroded reinforcement was cleaned up and damaged concrete was repaired. Dynamic modal tests were used before and after the transportations to determine if there was any damage caused by these specified overloads

Improved and more continuous condition assessment of bridges has been demanded by our society to better face the challenges presented by aging civil infrastructure. Indeed, the recent collapses of the Hintze Ribeiro Bridge that killed 59 people, in Portugal, and the I-35W Bridge in the United States, that killed 13 people, pointed out the need for new and more reliable tools to prevent such catastrophic events. Besides those events, the financial implications and potential impact through optimal bridge management are vast. For instance, facing an ageing infrastructure, the United Kingdom Government’s 2010 Infrastructure Plan signaled the need for enormous investments in infrastructures, equivalent to £200 billion over the next five years. On the other hand, the American Society of Civil Engineers reports the cost of eliminating all existing US bridge deficiencies at $850 billion. These values clearly show that planned bridge maintenance can lead to considerable savings. In the last ...

Recently a bridge on Savitri River Mumbai-Goa Highway near Mahad, about 170 km from Mumbai collapsed due to heavy rain and flood which was built in British era. The age of bridge is approx 100 years. Similar examples have been seen around which result in heavy loss of lives and public property. As a structural Engineer it is a need of the hour to maintain existing structure with rehabilitation and strengthening as per the requirement for safety. This paper reviews the literature of various approaches for condition / damage assessment of structures. Damage assessment initiates to adopt the most efficient approaches to ensure the most effective method. In this paper an attempt for selection of methods for condition assessment of bridge structures.