Editor’s Note

The March 2010 issue of the ASCE Journal of Bridge Engineering begins with three technical papers on long-span bridges. “Experimental Investigation of Bending Fatigue Response of Grouted Stay Cables” by Wood and Frank presents outcome on an experimental investigation to determine the susceptibility of grouted stay cables to bending fatigue damage. Fretting of adjacent wires within a single strand has been found to be the dominant cause of bending fatigue damage in the grouted stay-cable specimens. This damage tends to be concentrated at the ends of the specimens and at locations where concentrated loads were applied to the stays. The laboratory tests indicate that the risk of bending fatigue damage was low at the tension rings, along the free length of the stays, and in the vicinity of unintentionally crossed strands. “Operational Requirements for Long-Span Bridges under Strong Wind Events” by Cheung and Chan presents a simulation approach to estimate the operational driving speed limit on bridges subjected to different road conditions and wind intensities by considering the interactions between wind, vehicles, and the bridge. By applying the proposed approach to the Confederation Bridge in Canada, the authors show that similar to high-sided vehicles, light-weighted vehicles are also likely to suffer from instability problems on bridges even under relatively low wind velocity. The authors show that different types of vehicles can undergo different instability mechanisms under the same wind condition and these vehicle instability mechanisms vary with the wind velocity. “Engineering the Tower and Main Span Construction of Stonecutters Bridge” by Morgenthal, Sham, and West describes the fabrication and erection procedures for the bridge towers and the main span superstructure of the Stonecutters Bridge, the second longest cable-stayed bridge in the world upon completion and the first major bridge with a twin-box girder superstructure. The authors outline studies undertaken to achieve an effective construction, ensure structural adequacy of all erection stages, ascertain an acceptable aerodynamic performance of the bridge, and exercise full control over the bridge geometry throughout the erection process.

The next five technical papers are in diverse areas of bridge engineering. “Long-Term Wireless Structural Health Monitoring of the Ferriby Road Bridge” by Hoult, Fidler, Hill, and Middleton evaluates the potential of wireless sensor networks (WSNs) for use in bridge management through installation on the Ferriby Road Bridge, a three-span reinforced concrete bridge. Three displacement transducer nodes were placed across cracks on the soffit of the bridge to measure the change in crack width. Three inclinometer sensor nodes were mounted on two of the elastomeric bearing pads to measure the change in inclination of the bearing pads while a final node-monitored temperature in the box that contained the gateway. The deterioration data from the sensor network so far has shown little variations in measured quantities because of short duration of the data collection. “Comparison of Block-Shear and Whitmore Section Methods for Load Rating Existing Steel Truss Gusset Plate Connections” by Higgins, Senturk, and Turan focuses on the design of gusset plate connections in truss bridges. In this paper, differences between rating outcomes from block shear analysis at strength conditions with designs that employed allowable stresses on the Whitmore section method have been identified and expected outcomes for LRFR rating of gusset plate connections are proposed. “Higher Level Evaluation of a Reinforced Concrete Slab Bridge” by Jáuregui, Licon-Lozano, and Kulkarni proposes a method of load rating for reinforced-concrete slab bridge by determining a more accurate value for the equivalent strip width using higher level evaluation techniques. By analyzing a continuous reinforced-concrete slab bridge by the AASHTO Load and Resistance Factor Rating (LRFR) analysis, carrying out a diagnostic test to measure live-load strains and analyzing by finite-element method, this paper shows that the equivalent strip widths for positive moment are 26.1 and 22.1% greater than those calculated by the AASHTO approximate method for the exterior and interior spans, respectively. The refined widths for negative moment are greater than AASHTO by 13.1 and 11.1% for the exterior and interior spans, respectively. This increase in the equivalent strip width reduces the live-load effects, which proportionally increases the rating factors. “Optimum Design of Bridge Abutments under Seismic Conditions: Reliability-Based Approach” by Basha and Sivakumar Babu focuses on the reliability-based design optimization of gravity wall bridge abutments when subjected to active condition during earthquakes through an analytical study considering the effect of uncertainties in the seismic analysis of bridge abutments. Their analysis provides the optimum proportions of the abutment needed to maintain the stability against three modes of failure—sliding failure of the wall on its base, overturning failure about its toe (or eccentricity failure of the resultant force), and bearing failure of foundation soil below the base of wall—by targeting various component and system reliability indices. “C. Shaler Smith” by Griggs highlights the contributions of C. Shaler Smith, one of the premier bridge builders of the post-Civil War period. The paper discusses major viaducts, swing, and fixed-span bridges in the United States, Australia, and Peru, and innovative cantilever bridges over the Kentucky, Mississippi, and St. Lawrence Rivers designed by C. Shaler Smith.

The technical note “Importance of the Tail in Truck Weight Modeling for Bridge Assessment” by OBrien, Enright, and Getachew, based on extensive WIM measurements from two European sites, shows the sensitivity of the characteristic traffic load effects to the fitting process of statistical distributions to histograms of weight measurements. The authors propose a semiparametric fitting procedure by making a direct use of the measured histogram with reliable and sufficient data and parametric fitting to a statistical distribution in the tail region where there are less data.

The final three articles include two discussions and one closure. In the discussion of “Live Load Radial Moment Distribution for Horizontally Curved Bridges” by Woo, Laman, and Linzell, the discusser Abrahams points to confusion in the paper over the application of trucks and lane loads as per AASHTO Standard Specifications and the AASTHO LRFD code. The authors have provided a closure to the discussion on “Live Load Radial Moment Distribution for Horizontally Curved Bridges.” In the discussion of “Damage Localization and Finite-Element Model Updating Using Multiresponse NDT Data” by Sanayei et al., the discussers Yi and Wang raise several issues about the damage localization and finite-element updating approaches using multiresponse NDT data, including the differences between stiffnesses identified by using static and dynamic data, lack of data quality check, objective error function not including the weights on the level of different measurements errors, and grouping of connections into “outer” and “inner” connections.