Journal of Bridge Engineering

The abutments of integral bridges are traditionally supported on a single row of steel-H-piles that are flexible and that are able to accommodate lateral deflections well. In Hawaii, steel-H-piles have to be imported, corrosion tends to be severe in the middle of the Pacific Ocean, and the low buckling capacity of steel-H-piles in scour-susceptible soils has led to a preference for the use of drilled shaft foundations. A drilled shaft-supported integral abutment bridge was monitored from foundation installation to in-service behavior. Strain gauge data indicate that drilled shaft foundations worked well for this integral bridge. After 45 months, the drilled shafts appear to remain uncracked. However, inclinometer readings provide a conflicting viewpoint. Full passive earth pressures never developed behind the abutments as a result of temperature loading because thermal movements were small and the long term movements were dominated by concrete creep and shrinkage of the superstructure that pulled the abutments towards the stream. In the stream, hydrodynamic loading during the wet season had a greater effect on the abutment movements than seasonal temperature cycling. After becoming integral, the upright members of the longitudinal bridge frame were not vertical because the excavation and backfilling process caused deep seated movements of the underlying clay resulting in the drilled shafts bellying out towards the stream. This indicates the importance and need for staged construction analysis in design of integral bridges in highly plastic clays. Also, the drilled shaft axial loads from strain gauges are larger than expected.

The majority of integral abutment bridges (IABs) in the United States are supported on steel H-piles to provide the flexibility necessary to minimize the attraction of large lateral loads to the foundation and abutment. In Hawaii, steel H-piles have to be imported, corrosion tends to be severe in the middle of the Pacific Ocean, and the low buckling capacity of steel H-piles in scour-susceptible soils has led to a preference for the use of concrete deep foundations. A drilled shaft-supported IAB was instrumented to study its behavior during and after construction over a 45-month period. This same IAB was studied using the finite-element method (FEM) in both two- (2D) and three dimensional (3D). The 3D FEM yields larger overall pile curvature and moments than 2D because in 3D, the high plasticity soil is able to displace in between the drilled shafts thereby “dragging” the shafts to a more highly curved profile while soil flow is restricted by plane strain beam elements in 2D. Measured drilled shaft axial loads were higher than the FEM values mainly due to differences between the assumed and actual axial stiffness and to a lesser extent on concrete creep in the drilled shafts and uneven distribution of loads among drilled shafts. Numerical simulations of thermal and stream loadings were also performed on this IAB.

Integral abutment bridges (IABs) with short steel H-pile (HP) supported foundations ( $⩽4\text{m}$ of pile depth) are economical for many environmentally sensitive sites with shallow bedrock. However, such short piles may not develop an assumed, fixed-end support condition at some depth below the pile cap, which is inconsistent with traditional pile design assumptions involving an equivalent length for bending behavior of the pile. In this study, the response of an IAB with short HP-supported foundations and no special pile tip details such as drilling and socketing is investigated. Instrumentation of a single-span IAB with 4-m-long piles at one abutment and 6.2- to 8.7-m-long piles at the second abutment is described. Instrumentation includes pile strain gauging, pile inclinometers, extensometers to measure abutment movement, earth pressure cells, and thermistors. Pile and bridge response during construction, under controlled live load testing, and due to seasonal movements are presented and discussed. Abutment and pile head rotations due to self-weight, live load, and seasonal movements were all found to be significant. Measured abutment movements were likely affected by both temperature changes and deck creep and shrinkage. Based on the field study results presented here, moderately short HPs driven to bedrock without special tip details appear to perform well in IABs and do not experience stresses larger than those seen by longer piles.

One of the main components in girder-type bridges is bridge girder. This paper presents experimental data on the behavior and shear strength of concrete bridge girders reinforced with carbon fiber-reinforced polymer (CFRP) stirrups. A total of four large-scale reinforced concrete beams with a total length of 7,000 mm and a T-shaped cross section were constructed and tested up to failure. The test variables were the type and ratio of shear reinforcement (stirrups). The test beams included three beams reinforced with sand-coated CFRP stirrups of 9.5-mm-diameter spaced at $d/2$ , $d/3$ , and $d/4$ (where $d$ is the beam depth) and a control beam reinforced with conventional steel stirrups of 9.5-mm-diameter spaced at $d/2$ . The geometry of the test prototypes were selected to simulate the New England Bulb Tee (NEBT) beams that are being used by the Ministry of Transportation of Québec, Canada. As designed, three beams failed in shear due to CFRP stirrup rupture or steel stirrup yielding. While, the forth one, reinforced with CFRP stirrups spaced at $d/4$ , failed in flexure due to yielding of longitudinal reinforcement. The test results were compared to predictions provided by different codes and design guidelines. The current ACI 440.1R-06 design method provides conservative predictions; however, the CAN/CSA S6-06 and JSCE 1997 underestimate the contribution of the FRP stirrups due to low strain limits.

Recent research has culminated in the development of moment redistribution design and rating procedures based on a “rotation compatibility” procedure. The key aspects of the rotation compatibility method are presented herein along with the resulting series of simple equations that may be used for both design and rating of straight continuous-span steel I-girders. This procedure has several advantages over the previous moment redistribution procedures. Most significantly, the rotation compatibility method provides a rational basis for removing the current restrictions on girder geometries permissible for use with moment redistribution provisions. Thus, sections that are more slender and/or have greater unbraced lengths, compared to previous inelastic procedures, may be considered. This is particularly beneficial for incorporating inelastic methods into rating specifications because many existing bridges have geometries such that they have previously been outside the scope of applicability of inelastic procedures. A second key advantage of the rotation compatibility procedure is that maximum allowable redistribution moments are specifically computed, which justifies the use of higher levels of moment redistribution and consequently greater design economy in some cases.

Ultrahigh performance concrete (UHPC) has been used in several bridges and other structures throughout the world and is beginning to gain more exposure in the United States. For UHPC to continue to gain acceptance for bridge design in the United States, design specifications and procedures must be established for bridge engineers to utilize. The flexural behavior at the ultimate limit state for an UHPC girder is still a significant design concern. Therefore, this research examined three analytical approaches to evaluate the ultimate flexural strength of UHPC girders. In addition, Monte Carlo simulations were performed to account for the variability of several parameters and to determine reliability indices using the three analytical methods. The analysis results show that using typical AASHTO procedures, acceptable levels of reliability can be achieved while allowing the use of familiar and noncomplex equations.

Elastomeric bearings are widely used in bridge supports to accommodate thermal and other movements. The study presented in this paper extends an earlier investigation of two-dimensional bearing performance to three dimensions. Large-deformation rubber hyperelasticity is reviewed and a theoretical model is described with the steel-reinforced bearing subjected to compression in the direction through the thickness followed by shear in various lateral directions, including bridge longitudinal and transverse directions. Computations are carried out using the general-purpose, finite-element analysis computer program, ABAQUS. Conclusions are drawn regarding the effects of shear direction on bearing behavior.

This paper presents experimental and analytical work conducted to explore the feasibility of using an innovative technique for seismic retrofitting of RC bridge columns using shape memory alloys (SMAs) spirals. The high recovery stress associated with the shape recovery of SMAs is being sought in this study as an easy and reliable method to apply external active confining pressure on RC bridge columns to improve their ductility. Uniaxial compression tests of concrete cylinders confined with SMA spirals show a significant improvement in the concrete strength and ductility even under small confining pressure. The experimental results are used to calibrate the concrete constitutive model used in the analytical study. Analytical models of bridge columns retrofitted with SMA spirals and carbon fiber-reinforced polymer (CFRP) sheets are studied under displacement-controlled cyclic loading and a suite of strong earthquake records. The analytical results proves the superiority of the proposed technique using SMA spirals to CFRP sheets in terms of enhancing the strength and effective stiffness and reducing the concrete damage and residual drifts of retrofitted columns.

The paper presents the static loading of four long-span deep-corrugated steel box culverts with spans of 14 and 8 m. The tests, which were part of a series of full-scale tests, involved strain and displacement measurements carried out at different cover depths under the load of a truck. Two of the culverts were stiffened at the crown. The test results showed that the stiffening applied on the culverts is quite effective and that plain structure is more sensitive to cover depth compared to stiffened structure. The crown stiffening is more effective under shallow soil covers. The maximum displacement of plain structure is approximately twice the maximum displacement of the stiffened structure measured at 45-cm depth of cover. The Swedish and Canadian design methods are conservative when estimating live load moments but they underestimate live load thrusts. The measured maximum thrusts are up to four times larger than the calculated design values where the variation depends on the size of the culverts and the depth of soil. The culvert size has considerable influence on the thrusts and moments generated at the crown centerline, which could be implemented in the design models.

This paper develops a simplified method using a summation procedure and a related computer program to calculate the time-dependent behavior of a concrete filled steel tubular (CFST) arch bridge based on the geometric compatibility principle, a step-by-step time incremental process, and self-equilibrium equations. An experimental test on a scaled (1:5) segmental model of the main arch ribs of the Maocaojie Bridge was used to confirm the effectiveness of the proposed calculation method for evaluating the long-term behavior of CFST arch bridge under sustained load. It is concluded that: (1) the numerical results were in good agreement with the experimental results, demonstrating that the proposed analytical model is capable of predicting long-term effects for CFST arch bridges; (2) the stresses in the steel tubes increased, and the compressive stresses in the concrete decreased due to the effects of concrete creep and shrinkage. The maximum relaxation of the compressive stress in concrete due to concrete creep was 52.7% of the initial concrete stress, and the maximum increase of stress in the steel tubes was 27.3%; and (3) more than 90% of the total creep of the concrete took place in the first year. Subsequent creep of the concrete was limited because of the lack of water exchange between the structure and atmosphere and the reduction of compressive stress in the concrete.

The primary focus of this paper is to develop an understanding of temperature changes introduced by hydration heat release in the first few hours after casting in the thermal movements and stresses of the concrete deck and girders. Temperature and strain measurements from a simply supported, single-span, steel girder bridge with a composite concrete deck are presented. It is shown that setting occurs during the temperature rise and partial strain compatibility between steel girder and concrete deck is initiated at the end of the concrete temperature rise. Full strain compatibility between concrete deck and steel girder is achieved at the end of the cooling period following the initial temperature rise. The stresses in the steel girder associated with temperature changes are interpreted using an analytical model. It is shown that the concrete deck gains sufficient stiffness at the end of the temperature rise to restrain the movement of the top flange. Concrete deck movement in the period associated with cooling following the initial temperature rise is restrained, which could potentially produce tensile stress in concrete. The magnitude of tensile stress at the end of the cooling period depends upon the difference in the temperatures of the concrete deck and top flange and on the temperature gradient in the steel girder at the end of the heating period.