Editor’s Note

This issue of the Journal begins with two companion papers on transverse cracking in bridge decks. “Transverse Cracking of Concrete Bridge Decks: State-of-the-Art” by Hadidi and Saadeghvaziri presents the results of a comprehensive literature review of the causes of transverse deck cracking. Experimental and analytical research results are included, as well as survey studies on the effects of different factors affecting deck cracking. The literature review revealed that material and mixed design and construction practices have been heavily investigated in the past, but little work has been done to investigate the effect of structural design factors on deck cracking. In the second paper, “Transverse Cracking of Concrete Bridge Decks: Effects of Design Factors,” Hadidi and Saadeghvaziri present results of a comprehensive finite-element study of deck and girder bridge systems. The purpose of the study was to understand and evaluate crack patterns, stress histories, and the relative effect of different design factors on transverse deck cracking. The authors conclude with recommendations on preventive measures that can be adopted during the design stage that will minimize the potential for transverse cracking.

Cheng, Mo, and Yeh, in “Evaluation of As-Built, Retrofitted, and Repaired Shear-Critical Hollow Bridge Columns under Earthquake-Type Loading” investigate the seismic performance of as-built, retrofitted, and repaired hollow bridge columns with insufficient shear strength. Two full-scale columns were tested, repaired with CFRP jackets and dog-bone shaped bars, and then retested. Two other identical columns were retrofitted using only CFRP jackets. Test results and analysis showed that the CFRP composites can effectively strengthen shear-critical hollow bridge columns and successfully shift the failure mode from shear to flexure.

In the fourth paper, “Reliability-based Load and Resistance Factor Rating Using In-Service Data,” Bhattacharya, Li, Chajes, and Hastings present a probability-based methodology for load-rating bridges using site-specific in-service structural response data in a load factor and resistance rating format. Using site-specific structure response eliminates a substantial portion of modeling uncertainty in live-load and results in more accurate live-load ratings. Results from the proposed methodology are compared to ratings developed from traditional methods.

“Simplified Method for Calculating Lateral Distribution Factors for Live Load Shear,” by Huo, Wasserman, and Iqbal, presents a simplified equal distribution factor for live load shear. This study provides a careful examination and modification of the method by comparing shear distribution factors with those obtained from a finite-element analysis and other code-specified methods for actual bridges. Twenty-four bridges were studied and the authors determined that with proper modifications, the simplified method can produce very reasonable and reliable distribution factors for live load shear.

Lehman, Roeder, and Larsen, in “Design of Cotton Duck Bridge Bearing Pads,” investigate the engineering response to cotton duck bearing pads. These pads are constructed of alternating layers of elastomer and fabric. Although it is a versatile, economic, and widely used type of bearing pad, its engineering behavior has not been studied in detail. An extensive experimental research study was conducted to obtain this information. The results indicated that these bearing pads have significant stress and deformation capacities, and the study investigated various types of failure modes. The authors conclude with proposed quality control provisions in order to ensure adequate engineering performance of the pads.

In the next paper, “Using Inclinometers to Measure Bridge Deflection,” authors Hou, Yang, and Huang present a simple, practical, and inexpensive method for measuring static and dynamic deflections of bridge spans under loads. The inclinometer method is a promising bridge deflection measurement method for situations where it is difficult to directly measure bridge deflection. In contrast to other deflection methods, this method does not require fixed observation positions. The authors feel that this technique offers significant potential and present the results of their work using this methodology.

The last three papers are by Manko and Beben and address the subject of flexible load-carrying bridge structures that interact with soil. In “Tests during Three Stages of Construction of a Road Bridge with a Flexible Load-Carrying Structure Made of Super Cor Type Steel Corrugated Plates Interacting with Soil,” the authors measured the actual displacements and strains at selected points of the steel shell and found them to be smaller than the computed values. The results of this work can be useful in determining the interaction between the steel shell and the backfill for these types of structures. In “Research of Steel Shell of a Road Bridge Made of Corrugated Plates during Backfilling,” the findings for research conducted on a backfilled shell structure constructed of corrugated steel plates are presented. In “Static Load Tests of a Road Bridge with a Flexible Structure Made from Super Cor Type Steel Corrugated Plates,” Manko and Beben present the results for three static load schemes.

There is a technical note in this issue of the Journal—“Locality of Truck Loads and Adequacy of Bridge Design Load” by Lindt, Fu, Zhou, and Pablo. This technical note discusses the difference between the actual moments and shear in primary members of randomly selected bridges against the values that would be used by the current risk-based practice codes. The authors found that the reliability indices varied significantly among the bridge sites and types selected. In addition, they found that the results would be an inadequate design load for the Detroit area.

This issue of the J. Bridge Eng. concludes with a discussion and closure on “Simplified Method of Lateral Distribution of Live Load Moment” by Huo, Wasserman, and Zhu. In the discussion, Mr. Peter Kocsis provides his comments on the method as well as other issues relating to the lateral distribution of loads. In their closure, the authors respond to Mr. Kocsis’s comments and observations.