MAINTAINING BRIDGE SAFETY AND SERVICEABILITY UNDER INCREASING TRUCK LOADS Bala Sivakumar, P.E. 1 Abstract Though bridges compose a small percentage of total highway mileage, their costs, construction time, and traffic disruption upon failure or temporary closing significantly impact highway system performance. Bridge deterioration analysis shows bridge damages increase significantly with incremental weights. Competitive modern commerce is continuously demanding loads well in excess of the current standards Bridge owners need to control the loading on the bridges to limit the deterioration of the existing bridge infrastructure. Several truck weight studies have highlighted the problem of increasing truck weights and their impacts on infrastructure. Bridge design codes, which were once primarily focused on design for strength and stability, have evolved to incorporate consideration of bridge serviceability and durability. In this regard, understanding increasing traffic loads holds the key to our understanding of bridge serviceability and durability. This paper discusses the impact of increasing truck loads on bridge decks and supporting members, including the likely deterioration mechanisms and long term durability. Introduction The truck industry is faced with the demand of increasing truck weight in order to get more carrying capacity. The modern freight industry has been pushing the limits of traditional standards for truck size and weight. Competitive modern commerce is continuously demanding loads well in excess of the current standards established by various federal and state departments of transportation. On the other hand, bridge owners need to control the loading on the bridges to limit the deterioration of the existing bridge infrastructure in the United States and to keep the structures in a safe condition. Freight loads that exceed design standards are accelerating the deterioration of the pavement and bridge infrastructure. Bridge deterioration analysis shows bridge damages increase significantly with incremental weights. Though bridges compose a small percentage of total highway mileage, their costs, construction time, and traffic disruption upon failure or temporary closing significantly impact highway system performance. Moreover, the catastrophic nature of bridge failures in terms of fatality, property loss, and traffic disruption necessitates maintaining the structural integrity and serviceability of bridges and merits substantial consideration. Regulations are constituted to allow the truck weights to increase to a certain range while guaranteeing the safety and serviceability of the bridge system. Until the mid-1970’s, the legal limit on trucks was 73,280 lbs (33.2 metric-tons). Today it is 1 Bala Sivakumar, P.E., Vice President, HNTB Corporation, New York, USA.
MAINTAINING BRIDGE SAFETY AND SERVICEABILITY UNDER INCREASING TRUCK LOADS
Jul 01, 2023
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