Editor’s Note

This issue of the Journal of Bridge Engineering leads off with a timely paper on an emergency bridge-replacement case study. “Rapid Bridge Replacement under Emergency Situation: Case Study” by Bai, Burkett, and Nash presents the results of a research project that was conducted to identify strategies and technologies for quickly restoring a damaged bridge. One of the tasks was to do case studies of previous bridge replacements that were performed following such extreme events as explosions and fire following vehicle impact, vessel collision with a bridge, and damage caused by floods and earthquakes. By using these cases, the authors identified the solutions that worked well and those that did not, on the basis of the circumstances of the incident. This information provides valuable information for engineers who need to develop and implement emergency response plans.

The next two papers are on the subject of permitting and overload vehicles. “New Methodology: Permit Checking of Vehicular Overloads,” by Correia and Branco, presents a new methodology for permit checking of vehicular overloads on the basis of an initial statistical study performed to characterize these vehicles. By employing a vehicular overload database and a GIS representation of the highway network, the authors use software that performs a simplified structural safety analysis of the bridges crossed by the overload vehicle. As a result, prompt, economical, and safe permit decisions can be provided.

In the second overload paper, “Approximate Analysis of Bridges for the Routing and Permitting Procedures of Overweight Vehicles,” Vigh and Kollár present a method for comparing the mechanical effects of overweight and design-load vehicles on bridges. To date, the method has been a reliable tool for the permitting process of overweight vehicles and has been verified by several thousand comparisons.

In “Full-Scale Measurements to Investigate Rain–Wind-Induced Cable-Stay Vibration and Its Mitigation,” Phelan, Sarkar, and Mehta present observations from selected full-scale data and compare them with wind-tunnel test results as well as with results found in publications. The authors determined that wind-tunnel tests indicate that a distributed passive mitigation device installed on one of the cable stays to control rain/wind vibration is very effective.

The fifth and sixth papers discuss steel bridges. The first one is titled “Optimal Inspection Scheduling of Steel Bridges Using Nondestructive Testing Techniques.” In this paper, Chung, Manuel, and Frank propose a probabilistic approach for selecting the most suitable nondestructive inspection technique and optimal schedule for fracture-critical member/detail fatigue inspections for a specific steel bridge. The authors formulate a cost function that is based on combining probability calculations by using a probability-of-detection function with numerical Monte Carlo simulations of crack propagation of the fracture-critical detail. The selection of a nondestructive inspection technique with an associated inspection schedule is formulated as an optimization problem that will yield a minimum total cost. A case study for a box girder is used to demonstrate the proposed method.

In “Fatigue Damage of Steel Bridges Due to Dynamic Vehicle Loads,” MacDougall, Green, and Shillinglaw look at the fatigue damage that occurs in steel bridge girders because of the dynamic tire forces that occur during the crossing of heavy transport vehicles. The paper quantifies the difference in fatigue life of short-span and medium-span bridges that is attributable to successive passages of steel-sprung or air-sprung vehicles. The modal properties of the bridge are obtained by modeling the bridges as beams. The responses of the bridge are predicted by using a convolution method by combining the bridge modal properties with the vehicle wheel force. The crack growth is predicted with a linear elastic fracture mechanics model. The work found that the steel-sprung vehicle caused fatigue failure up to 6.5 times faster than an air-sprung vehicle for short-span bridges. For medium-span bridges, the steel-sprung vehicle caused fatigue failure up to 277 times faster.

“Torsional Design of Hybrid Concrete Box Girders” is the first of two papers on concrete bridges. Mo and Fan use a previously performed series of systematic tests to present a step-by-step procedure for the torsional design of hybrid concrete box girders constructed with prestressed concrete slabs and corrugated steel webs, as opposed to the traditional concrete box girders. This type of construction significantly reduces the weight of the girders and allows the span length to be increased. A sample girder is checked by using the proposed design procedure, and is shown to satisfy structural codes.

The second concrete-bridge paper is “Long-Term Behavior of Precast Segmental Cantilever Bridges.” In this paper, Iglesias presents an investigation that was performed to quantify long-term effects on four similar precast segmental bridges. Of particular interest were the effects of long-term deformations of concrete.

Aidoo, Harries, and Petrou discuss an experimental study of the behavior of eight reinforced concrete bridge girders retrofitted with three different carbon-fiber-reinforced polymer (CFRP) systems in “Full-Scale Experimental Investigation of Repair of Reinforced Concrete Interstate Bridge Using CFRP Materials.” They found that intermediate crack-induced debonding was the dominant mode of failure for monotonically loaded beams and that fatigue degrades the CFRP-to-concrete interface.

An additional paper on composite materials is the tenth paper in this issue of the Journal of Bridge Engineering. In “Seismic Performance of Concrete-Filled FRP Tube Columns for Bridge Substructure,” Zhu, Ahmad, and Mirmiran present an investigation on the construction feasibility and seismic performance of structural joints for concrete-filled fiber-reinforced polymer tubes used in the construction of bridge substructures. The investigation employed a control reinforced-concrete column and three composite columns supported on similar reinforced concrete footings. The columns were loaded with constant axial load along with pseudostatic lateral load. The proposed joints proved to be feasible to construct and functioned well when exposed to extreme load conditions. The composite columns demonstrated that they were a significant improvement over the reinforced-concretecontrol column for both ultimate strength and ductility.

The last paper in this issue of the Journal is “Property Modification Factors for Seismically Isolated Bridges” by Warn and Whittaker. The authors investigated how changes in the mechanical properties of individual seismic isolators affect the response of isolated bridge structures subjected to an earthquake. Analysis using nonlinear response history was performed with recorded earthquake ground motion. Twenty bilinear isolation systems were used in the study so that the work would be applicable for the design of seismic isolation systems across the United States. Threshold values are determined for the property modification factors that engineers could use to perform preliminary design and assessment of an isolation system before performing bounding analysis, as currently required by bridge and building design codes.

This month, two discussions and one closure paper cover previously published papers in the Journal of Bridge Engineering. In a discussion of “Fatigue Performance of Stringer-to-Floor-Beam Connections in Riveted Railway Bridges,” W. G. Byers offers his observations of the types of rivet failures that he has observed in railway bridges, as well as the changes in past versus current practice in the design and detailing of the connections. In addition, he offers an additional failure mechanism for this connection, as well as a possible explanation for the problem.

In a discussion of “Impact Factors for Horizontally Curved Composite Box Girder Bridges,” D. Huang indicates that the vehicle model and some assumptions used by the authors warrant further discussion, particularly the vehicle-bridge interaction and the impact factor used for the support reaction.

In the closure to “Impact Factors for Horizontally Curved Composite Box Girder Bridges,” Sennah, Zhang, and Kennedy clarify the issues of vehicle/bridge weight, as well as the impact factor used for the supports.