Journal of Bridge Engineering

Method II of the American Association of State Highway and Transportation Officials (AASHTO) Guide Specification and Commentary for Vessel Collision Design of Highway Bridges focuses mainly on ship impact design. Consequently, the current specifications in Method II are limited mainly to bridges in maritime waterways. Bridges over inland waterways, though, are more susceptible to impact from barges. However, no inland waterway bridges are known to have been designed for barge impact using Method II due to the tremendous variation in flotilla sizes, barge types, and barge sizes. A method by which available barge and flotilla data may be utilized to develop the risk assessment procedures for vessel impact design problems in accordance with design Method II is presented. The methodologies presented in this paper are applicable to all navigable inland waterways in the United States and the world. For illustrative purposes, a design example is included which utilizes barge traffic data from rivers in Kentucky.

During the last few decades, composite steel-concrete structures have been used widely to form the basic superstructure for numerous bridges. Proper design of the deck slab for such bridges requires a proper estimate of their punching strength. Current codes of practice do not take into account the influence of skew and other factors on the punching strength of deck slabs in skew composite bridges. One code of practice suggested, but without substantiation, that for deck slabs in bridges with skews exceeding 20°, a reinforcement ratio of 0.6% should be used in the end portions near the supports. In this paper, the influence of several factors on the punching strength of deck slabs of skew composite steel-concrete bridges is examined. These factors include: reinforcement ratio, angle of skew, deck thickness, load position, shear connectors, size and spacing of longitudinal girders, and cross-bracing. An experimental study was conducted on seven simply supported skew composite steel-concrete bridge models to verify the analytical nonlinear finite-element solution. Based on a parametric study a formula is proposed, which permits the calculation of the punching strength of deck slabs in skew composite steel-concrete bridges, accounting for the various influencing factors.

The free vibration characteristics and the dynamic response to a multivehicle load moving across rough bridge deck of continuous and cantilever thin-walled box girder bridges are studied. The box girder bridge is divided into a number of thin-walled beam elements. Both warping torsion and distortion are considered in the study. The analytical vehicle is simulated as a nonlinear vehicle model with 11 independent degrees of freedom according to the HS20-44 truck design loading contained in the AASHTO specifications. Four different classes of road-surface roughness generated from power spectral density function for very good, good, and average roads are used in the analysis. One continuous and two cantilever three-span box girder bridges are designed based on the AASHTO specifications. The dynamic responses of the bridges are evaluated for single truck, three, and six trucks, with different speeds and road surface roughness. The analytical results show that the effects of different loading models, road surface profiles, and vehicle speeds on the dynamic response for different types of bridges are quite different. The most important factor which affects the impact of cantilever bridges is the vehicle speed.

This paper presents the comprehensive instrumentation program for the Sunshine Skyway Bridge, Florida, which has been carried out to monitor the bridge behavior during and after construction. The program includes the physical measurements of concrete compressive strength, modulus of elasticity, Poisson's ratio, coefficient of thermal expansion, shrinkage, creep, concrete strains, vertical deflections, and temperature distributions at selected locations of the Sunshine Skyway Bridge, Florida. A comparative study of the measured time-dependent strains of a typical pylon and segments of the bridge and the corresponding analytical predicted values are presented in a companion paper.

This paper presents a methodology for the analysis of stage-constructed prestressed-concrete bridges. The method uses the step-by-step superposition of strains and accounts for time-dependent effects including creep, shrinkage, and hardening of concrete and relaxation of prestressing steel. This analytical model has been developed as a synthesis of structural analyses and computations of time-dependent deformations. The predicted strains in the pylons show reasonable agreement with the measured time-dependent strains. The magnitudes of the predicted time-dependent strains in the box-girder segments, including the thermal effects, closely agree with the measured values. Time-dependent deformation relationships are derived for the strain variations for the pylon and segment erection sequence. The analytical model can be used to predict the behavior at any specified time during the construction stages. The methodology is demonstrated with a 10-yr prediction of the time-dependent strains by superposition of the effects of forces and moments resulting from the construction sequence.