Bridge Structures

The concept of cold-bent shallow press-brake-formed steel tub girders was developed by a technical working group within the Steel Market Development Institute’s (a business unit of the American Iron and Steel Institute) Short Span Steel Bridge Alliance, led by the current authors. This working group consists of all stakeholders in the steel bridge industry, including mills, fabricators, service centers, industry trade organizations, universities, and bridge owners. The scope of this effort is defined by three separate tasks. First, singular composite girders were fatigue tested by simulating a 75-year life in a rural environment. Second, two slab edge treatment methods were evaluated to determine the optimal option for the Ultra-High Performance Concrete (UHPC) joint between modular tub girder units. Lastly, two composite modular press-brake-formed tub girders were connected longitudinally with a UHPC joint and the system’s fatigue performance was evaluated. Experimental results show press-brake-formed tub girders behave adequately with respect to fatigue. Longitudinal joints composed of UHPC behaved satisfactorily throughout testing.

In Europe, a deck of a concrete bridge usually consists of several layers with specialized functions. The concept where all the functions are integrated into one layer (called “unprotected concrete bridge deck – UCBD” in this paper) is popular in the North America. This paper deals with design, construction and monitoring of the pilot UCBD structure in the Czech Republic. Considering the requirements on the structure and the material, polymer fiber reinforced concrete (PFRC) was selected as the most suitable alternative. The composition of the material was optimized during an extensive experimental program. The developed material was then applied on a small-span bridge on a local road. The presented pilot structure is the first of its kind in the Czech Republic and according to the knowledge of the authors, PFRC has not been used for UCBD anywhere else in Europe before. A cost analysis was carried out to estimate the economic efficiency of the solution. Total direct savings reached 5% of the total costs of the project. The pilot structure will be subjected to long-term monitoring with the aim to verify the reliability of the new concept and to perform a more detailed life cycle cost analysis. The results of monitoring after the first year showed satisfactory performance of the structure.

 Bridges are of particular importance among the structures built by human beings. Therefore, the desired seismic behaviour of this type of structures during the earthquake is of utmost importance. The friction pendulum system is considered as a type of sliding isolator in which sliding motion and recursive force are combined by isolator’s geometry. The effects of the earthquake directivity and the span-length of two multi-span continuous steel girder bridges were investigated in this study. The base shear created in the bridges depends on the bridge span, so that more base shear is applied on the bridge with longer spans. In both bridges, the base shear under records of a side with directivity feature was more than the other side. Deck displacement in the bridges in the side with directivity feature was significantly larger than the other side. This increase in structural displacement can lead to the pounding of the bridge deck on abutments. For this reason, it seems necessary to embed the appropriate expansion joints considering the effect of directivity of the earthquakes.

This paper describes a probabilistic approach to estimate the conditional failure probability of the existing bridges in Assam based on the present condition inspected data. The bridges are categorized considering Indian Road Congress (IRC) Bridge Maintenance Inspection manual and National Bridge Inventory System (NBIS), through implementing visual inspection method leading to condition assessment of the bridges available in the study area. Condition rating of the bridges considered mainly concrete decks and diverse roadways such as both rural and highways that helps in analyzing time-in-condition rating, reliability, and hazard function of the deck components. The Anderson-Darling (AD) test was adopted to find the suitable probabilistic models and shown that Weibull distribution becomes the best fit. However, the main importance is given on the maturity of the bridge which helps in evaluating the time-dependent probability of failure. These estimates would help researcher and practicing engineers in carrying out service life in long term analysis for bridge design, maintenance policy, and replacement decision of the study area in a cost-effective plan strategy with appropriate direction or solution in the bridge management system considering safety aspects in the study area.