Author: Peng LouPublisher:
ISBN:
Category : Bridges
Languages : en
Pages : 255
Book Description
Highway agencies are responsible for the optimal expenditure of taxpayer dollars allocated to highway infrastructure. Truck size and weight are regulated by federal legislation and every state highway agency has its own legal load limits. Over the last two decades, both the frequency and weight of overweight trucks has kept increasing. Although the AASHTO Load and Resistance Factored Design (LRFD) Bridge Design Specifications mandates a design life of 75 years, the actual service life of bridges is lower and varies from one bridge site to another. Additionally, state agencies issue permits for trucks with gross vehicle weights that are above legal load limits. However, the effect of overweight trucks on the service life of bridge components is not explicitly quantified. This dissertation presents a rational approach to investigate the impact of truck loads on bridges in New Jersey through the utilization of bridge inspection reports, truck weight-in-motion (WIM) data, and the National Bridge Inventory (NBI) database. Actual bridge deterioration modes were identified from their respective inspection reports. Based on the condition ratings from NBI, the expected service life for each bridge component on various highways were estimated. In addition, WIM data in New Jersey were used to extract the loading on bridges. For bridge decks and prestressed concrete (P/C) girders, the correlation between the expected service life and truck loadings was performed and prediction functions for service life were proposed. For steel bridge girder, predicted service life was calculated through the remaining fatigue life assessment. Lastly, Bridge Life Cycle Cost Analysis (BLCCA) was conducted using two contrasting scenarios, one with and the other without overweight trucks, to quantify economic impact of overweight trucks on bridges. The results show that deterioration mode of prestressed concrete (P/C) girders was the corrosion near the beam-ends induced by cracking and spalling while the deterioration mode of reinforced concrete deck was the punching shear failure. Overall, P/C girders have better performances than steel girders. During the lifetime of the bridge, the deterioration of P/C girders would be accelerated once cracking is initiated. The expected service life of P/C bridges was greatly affected by the condition of the bridge deck. Lastly, the results indicated that overweight trucks caused more damage on NJ state highways compared with interstate highways due to a larger proportion of overweight trucks, heavy wheel loads from overweight trucks, and fewer axles per truck.
