Editor’s Note

The November 2008 issue of the Journal of Bridge Engineering begins with a timely paper on the nation’s bridge infrastructure. “Impact of Commercial Vehicle Weight Change on Highway Bridge Infrastructure,” by Fu, Feng, Dekelbab, Moses, Cohen, and Mertz presents a new methodology for estimating the cost effects of truck weight limit changes on bridges in a transportation infrastructure network. Providing a tool to study the impacts of these changes, the authors found that the costs for relatively inadequate strength of existing bridges and the increased design requirement for new bridges were dominant in the total impact cost.

Hayworth, Huo, and Zheng in “Effects of State Legal Loads on Bridge Rating Results Using the LRFR Procedure” present the results of their research on the effects of different specified trucks on bridge ratings with the LRFR procedure. The rating trucks were applied on 16 selected Tennessee Department of Transportation bridges to obtain the LRFR ratings. The bridges represented four bridge types commonly used in the state. The research results revealed the validity of the LRFR tiered approach with regard to AASHTO legal loads. Some of the state’s heavier truck loads governed the HL-93 loads. Bridges with both high average daily truck traffic and short spans were more likely to be governed by state legal load ratings instead of HL-93 load ratings.

The third paper in this issue, “Dynamic Testing for Structural Identification of a Bridge.” by Morassi and Tonon, illustrates the advantages and indeterminacy characterizing structural identification problems for bridge structures.

Another timely paper, “Experimental Investigation of Multihazard Resistant Bridge Piers Having Concrete-Filled Steel Tube under Blast Loading,” by Fujikura, Bruneau, and Lopez-Garcia, presents the development and experimental validation of a multihazard bridge pier concept. The proposed concept consists of a multicolumn pier-bent with concrete-filled steel tube columns. The adequacy of this system is experimentally investigated under blast loading. It was found that the columns could be designed to provide satisfactory seismic performance and adequate blast resistance.

Sangree and Schafer in “Field Experiments and Numerical Models for the Condition Assessment of Historic Timber Bridges: Case Study” present two case studies that use a simplified approach to damage assessment. The importance of proper condition assessments, including both field observations and load tests and the creation of viable finite-element models that practicing engineers may use in the repair and rehabilitation of these bridges, is explored by the authors.

The next three papers are on the subject of concrete bridges. The first, “Flexural Behavior of an Ultrahigh-Performance Concrete I-Girder,” by Graybeal, presents the results of an investigation using testing and related analysis of a full-scale prestressed I-girder. Steel fiber-reinforced concrete was used to fabricate the girder containing prestressing strands and no mild steel reinforcement. Test results are compared to predictions based on standard analytical procedures, and a flexural design philosophy for this type of girder is proposed.

The second concrete-related paper, by Zhou, Li, and Imbsen, “Introduction of the Lateral Posttension Method for Prestressed Concrete Bridges,” describes a practical and inexpensive way of anchoring and applying the prestressing force for posttensioned concrete bridge superstructures. The method offers potential advantages for bridge rehabilitation and retrofit construction projects.

“Static Behavior and Theoretical Model of Stud Shear Connectors” by Xue, Ding, Wang, and Luo is the final concrete-related paper in this issue. The authors conducted 30 push-out tests on stud shear connectors to investigate the effects of stud diameter, stud height, concrete strength, stud welding technique, transverse reinforcement, and steel beam type on stud failure mode, load versus slip curve, and shear bearing capacity. Based on the tests, a new expression of the stud load-slip relationship is proposed, as well as a calculation model of stud shear-bearing capacity. The proposed changes yield results that more closely match the experimental results.

The final paper in this issue of the Journal of Bridge Engineering is a biographical piece on a bridge by Othmar Ammann. In their paper, “Bayonne Bridge: The Work of Othmar Ammann, Master Builder,” Thrall and Billington demonstrate the significance of the Bayonne Bridge as a work of structural art due to its efficiency, economy, and elegance.