Repair and Strengthening of Bridge Substructures

Deterioration of bridge substructures has been a serious concern throughout Wisconsin. Concrete, steel and timber members all require distinct repair methods which not only address the true causes of deterioration, but protect the member from future damage. Utilizing repair techniques that merely address the effect of the deterioration has proven costly and unreliable. Understanding the relationship between cost and service life of modern repair methods can help maintenance engineers make informed decisions that will maximize efficacy. A survey was sent to 90 maintenance engineers throughout the United States to determine the efficacy and cost of common repair methods. Unique repair procedures were also investigated based on the results of the survey. Eight bridges throughout the Southeast and Southwest regions of WisDOT were documented. These bridges displayed varying stages of deterioration as well as typical repair methods. By evaluating these bridges it was determined that the damage caused by deicing chemicals is extensive and varying. Expansion joint degradation has accounted for a large portion of deterioration throughout Wisconsin’s bridge infrastructure. Documentation indicating how long repairs had been in place gave the research team an estimate for longevity of repairs in Wisconsin. Repair methods were documented and analyzed for concrete, timber, steel and scour. They were considered for their longevity, relevance in Wisconsin’s climate, ease of completion and cost. Further organization highlighted repairs based on specific substructure element relevance, in an attempt to address unique deterioration by substructure member. After the repairs were analyzed, three separate decision matrices were created in order to compare differing repair methods. Decision matrices were created for concrete repairs, pile repairs and scour repairs. The pile repair decision matrix was created in lieu of separate timber and steel decision matrices, since those materials are typically only used for piles of modern substructures. These decision matrices can be used to design appropriate substructure repairs which will be both cost-effective and durable