Journal of Bridge Engineering

Accelerated bridge construction using precast bridge substructures can enable reduction of traffic disruption, increased worker safety, and increased quality through controlled conditions at the time of fabrication. A largely unrealized benefit of precast substructures is the use of pretensioned bent caps that can provide superior performance to that of reinforced concrete bent caps. Full-scale experimental tests of reinforced concrete (RC) and pretensioned, prestressed concrete (PSC) bent cap subassemblies were conducted to verify the improved performance of pretensioned caps. Flexural reinforcing bars and strands were distributed along the sides of the bent cap to accommodate a pocket connection designed to provide large construction tolerances. Results showed superior performance of the pretensioned cap, including delayed initial cracking, smaller average flexure crack widths, and absence of shear cracking. Removal of live loads resulted in full closure of cracks, validating the design philosophy of zero tension under dead load.

In this paper, an analytical algorithm, based on the bilinear resistance model, was proposed to analyze the track-bridge interaction on long-span steel bridges under thermal action. Calculation results show that the proposed algorithm is more accurate than previous analytical algorithms and can achieve nearly the same accuracy as the finite-element method (FEM), but is more efficient than FEM. Based on the algorithm, this paper explained why the longitudinal force (LF) in the middle of the bridges doesn't increase as bridge length increases, then proposed a manual LF calculation formula. Researchers and engineers can use this formula to easily estimate the maximum LF on bridges which have rail expansion devices (REDs). A parametric study was performed. The result shows that LF is not a matter of concern on the bridges with REDs. Besides, the relationships between track resistance distribution, track-bridge relative displacement and boundary conditions were revealed, and the difference between LF on bridge and on embankment were discussed. The outcomes of this paper can be applied to long-span centrosymmetric continuous bridge as well as cable-stayed bridges.

The installation of an external damper on a cable of a cable-supported bridge is often associated with attachments or support devices that trigger vibration restraints at the damper location. This paper investigates the effect of rotational restraint at the damper location on additional damping of a taut cable with an installed viscous damper. An asymptotic solution is employed to derive the asymptotic form of cable complex eigenfrequencies and its damping ratio, in which the flexural rigidity of the cable and those damper restraints including rotational stiffness, damper stiffness, and support stiffness are taken into account. The investigation by a numerical example indicates that by considering rotational restraint, the additional damping of a cable is always lower than its values in the case of no rotational restraint.

Seismic design principles of highway bridges across the globe have undergone significant modifications over the last decades, from little consideration of seismic effects to adoption of modern ductile detailing principles. The existence of bridges with such diverse design methodologies renders vulnerability assessment for future earthquakes particularly challenging. Consequently, robust analytical models are required to capture varied failure mechanisms of differently designed bridges to aid the systematic impact assessment of design code evolution on seismic fragility. This study addressed the need by developing high-fidelity nonlinear finite-element models that can simulate different structural failure modes (shear, flexure-shear, and flexure). Following analytical model validation with past experimental results, this paper presented a framework for the methodical assessment of design code evolution on seismic performance and failure probability of bridge piers. Results revealed significant improvement in seismic performance under successive design code revisions and highlighted the necessity to account for shear modeling in vulnerability assessment of older designed bridge piers. Lastly, the latest code provisions of leading international seismic design guidelines were compared to highlight key differences among code provisions that need attention for possible harmonization of various codes across the globe.

This study determined an explicit tolerance for bottom flanges of tub girders giving computed first yield moment including the strength reduction due to initial out-of-flatness of tub girders higher than the flexural design capacity for the limit state of bottom flange local buckling in current standards. Finite-element analysis (FEA) was used to construct flexural strength–reduction curves for tub girders with various out-of-flatness magnitudes covering a range of girder cross sections and spans. Tub bottom flange slenderness ratios between 25 and 120 were modeled as covering the practical range. Models were built with coexisting out-of-flatness in both webs and flanges. The appropriate residual stress pattern was created using heat analysis. Models were laterally supported to ensure the local buckling limit state controls. Both 344.7-MPa (Grade 50 Steel) and 689.4-MPa (Grade 100 Steel) yield steel plates were considered with elastic-perfectly plastic material behavior. Large deflection theory was used to iteratively capture the secondary moments due to out-of-flatness. The current tolerance of $D/150$ out-of-flatness for the fascia web of an I-shaped plate girder was shown to implicitly accept a 20% strength reduction. Results showed that compressive flexural design formulas for tub girders in current standards conservatively reduce the strength to account for local buckling. Code adoption of $b_f/200$ is recommended for the tub girder bottom flange out-of-flatness tolerance, where $b_f$ represents the bottom flange width.

Located over the St. Lawrence Seaway, the new Samuel De Champlain Bridge was designed and constructed in 48 months despite the severe winter of Montreal. Many factors, including a deteriorating existing bridge, limited construction periods, and severe weather constraints on large infrastructure projects such as this, often require the use of an accelerated bridge construction (ABC) approach. All the aforementioned factors were primary challenges for the new Samuel De Champlain Bridge project. To meet the fast-tracked schedule, design decisions for the signature cable-stayed bridge included maximizing the use of segmental construction, choosing steel over concrete for the pier caps, and adjusting the cable-stayed bridge closure joint location. Concrete elements, including pier legs and portions of the tower, were precast in modules and assembled using post-tensioning. Precasting allows work to continue through cold winter periods—when pouring in situ concrete would otherwise be very difficult and time consuming. Precasting also allows casting and erection to be carried out in parallel, rather than in series—as in conventional construction. The superstructure utilized precast deck panels to expedite deck construction. Steel elements were prefabricated at multiple shops to minimize field welding. Along with innovative erection sequencing, on-site construction time was minimized and the overall bridge construction was accelerated.