Editor’s Note

This issue of the Journal begins with two papers on old or historic bridges. In “Analysis and Solution to Human-Induced Lateral Vibrations on a Historic Footbridge,” Wilkinson and Knapton investigated a lateral vibration problem with the historic Cragside Bridge built in 1875. Like the recently constructed Millennium Footbridge in London, the Cragside Bridge was sensitive to lateral movement when it was lightly loaded. A computer model was used to determine the natural frequency of the bridge and to study various solutions to the problem.

The second paper on an old or historic bridge is Mammino, Tonon, and Tonon’s “Renovation of the 17th Century Ponte Lungo Bridge in Chioggia, Italy.” The paper describes the design and construction of the recent Ponte Lungo renovation. This renovation reconstructed a structure similar to the original bridge, but capable of supporting modern loads and needs.

In “Nonlinear Finite-Element Analysis of an FRP-Strengthened Reinforced Concrete Bridge,” Chansawat, Yim, and Miller developed three-dimensional nonlinear finite element models to examine the structural behavior of the Horsetail Creek Bridge strengthened by fiber-reinforced polymers. The results of these models were compared against field data of strains from trucks located on the beams at various locations. Using this information, the authors compared the structural responses of strengthened and unstrengthened bridge models in order to evaluate the FRP retrofit. The authors determined that the models predicted a significant improvement in the structural performance as a result of the FRP retrofit.

In the fourth paper, “Transverse Analysis of Strutted Box Girder Bridges,” Shushkewich presents the computer program STRUTBOX of the transverse analysis of strutted box girder bridges. Based on the folded plate method, the program allows the deck prestressing and other reinforcing to be proportioned for longitudinal shear and torsion and gives an indication as to the severity of shear lag effects.

Morano and Mannini’s “Preflex Beams: Method of Calculation of Creep and Shrinkage Effects” presents a method of calculation of creep and shrinkage effects for composite beams. The calculation is particularly important for preflex and flexstress beams in which the bottom flange is encased in concrete. The approach presented by the authors uses concrete age-adjusted modular ratio allowing the calculation of time-dependent stresses in the concrete flange due to creep and shrinkage. The results can be extended directly to the analysis of ordinary steel-concrete composite beams.

“Modified Skew Bending Model for Segmental Bridge with Unbonded Tendons,” by Huang and Liu, presents the results of analysis of the behavior of a prestressed segmental bridge with unbonded tendons under combined loading of torsion, bending, and shear. From experimental research, a modified skew bending model was developed to determine the load-carrying capacity of segmental bridges subjected to combined torsion, bending, and shear. Using the finite-element method, the authors investigated the deflection of the structure and checked the model. They found that the theoretical and REM results compared favorably with the test results, and the authors present suggestions for the design and construction of segmental bridges with external prestressing.

In the seventh paper of this issue, “Distribution of Compressive Stresses in Transversely Posttensioned Bridge Decks,” Smith-Pardo, Ramirez, and Poston conducted a parametric study of the significant aspects affecting the distribution of compressive stresses in transversely posttensioned concrete bridge decks. Alternative FEM techniques and alternative software was considered and analytical results were compared with the experimental results from previous investigations. It was determined that the distribution of compressive stresses is primarily affected by the support conditions of the girders and the axial stiffness of the diaphragms.

The next four papers are on steel bridges. In “Truck Models for Improved Fatigue Life Predictions of Steel Bridges,” Chotickai presents a new fatigue load model that was developed based on weigh-in-motion data collected from three different sites in Indiana. Using data from recorded truck traffic, loads were simulated over analytical bridge models to investigate the moment ranges. The models included simple and two equal continuous girder spans. Fatigue damage accumulations using Miner’s hypothesis were calculated at various locations on the bridge models and compared with the damage predicted based on the AASHTO fatigue truck, a modified AASHTO fatigue truck, and other fatigue truck models. It was found that the fatigue damage is overestimated for short girder spans. The author proposes two new fatigue trucks, one for typical highways and the other for heavy duty highways that have a significant percentage of its traffic composed of eight- to 11-axle trucks.

The next two steel bridge papers are companion papers by Chavel and Earls. The first is “Construction of a Horizontally Curved Steel I-Girder Bridge: Erection Sequence,” and the second is “Construction of a Horizontally Curved Steel I-Girder Bridge: Inconsistent Detailing.” In “Erection Sequence” the problems of fit-up problems are investigated. The authors show that the erection sequence used to construct these bridges should be comprehensively studied to ensure that the no-load condition assumed for detailing the members is achieved in the field. This paper presents research that investigated the erection of recently constructed horizontally curved steel I-girder bridge that had problems during erection. The results demonstrated that a condition that closely resembles the no-load condition can be achieved in the field through the use of temporary support structures. In the companion paper the authors investigate the problem of inconsistent detailing and its contribution to construction problems for horizontally curved I-girder bridges.

The last of the four steel girder bridge papers is “Characterization of the Material Properties of HPS-475 W (70 W) TMCP for Bridge Girder Application,” by Kayser, Swanson, and Linzell. The thermomechanical controlled processing (TMCP) method of production of HPS steel has certain advantages over the other method of production, quenching, and tempering. Unfortunately, while the TMCP method of production yields average ultimate strengths within acceptable limits, the average yield strengths are generally lower. Despite this problem, the TMCP method of production is a promising method for the production of steel for bridge applications.

This issue concludes with two papers on seismic-related issues. The 12th paper in this issue is authored by Kunde and Jangid. “Effects of Pier and Deck Flexibility on the Seismic Response of Isolated Bridges” investigates the seismic response of bridges isolated by elastomeric bearings and sliding systems under to horizontal components of real earthquake ground motion. The investigation concluded that the earthquake response of seismically isolated bridges can be effectively obtained by modeling it as a single-degree-of-freedom system supported on an isolation system in two horizontal directions.

The final paper, “Orthogonal Effects in Seismic Analysis of Skewed Bridges,” by Maleki and Bisadi, investigates the effects of seismic force direction on the responses of slab-girder skewed bridges. Various combination rules for orthogonal earthquake effects were examined. It was concluded that either the SRSS or the 100/40 percentage rule in the skew direction should be used in the response spectrum analysis of skewed bridges, and for time history analysis the application of paired acceleration time histories in several angular directions is recommended.

This issue includes a technical note, “Sensitivity of Live Load Distribution Factors to Vehicle Spacing,” by Patrick, Huo, Puckett, Jablin, and Mertz. The note investigates different live load placement configurations to determine the sensitivity of live load shear and moment to vehicle spacing.

Finally, there is a discussion and closure for “State-of-the-Art of Integral Abutment Bridges Design and Practice.” In the discussion by Kocsis, a simple method for computing the point of fixity for a pile is provided and discussed by the author. In the closure, original paper authors Arockiasamy, Butrieng, and Sivakumar respond to the discussion author’s points and provide additional clarification regarding their paper.