Journal of Bridge Engineering

The concept of performance-based seismic design dates from the 1990s. Several complex bridges in seismic hazard zones were designed following this concept. The list includes but not limited to the New Carquinez Suspension Bridge, the New Tacoma Narrows Suspension Bridge, and the Gerald Desmond Bridge. This paper documents the fundamental issues that were considered in the seismic design of recent cable-supported bridges including the seismic performance-based criteria (PBDC). The paper also discusses how the local damage levels are employed through a deformation-based approach to achieve the global performance objectives of the bridge. The paper also explains the development procedure of spectrum compatible ground motions through probabilistic seismic hazard analysis. Issues such as foundation modeling, soil–structure interaction, and appropriate damping are also outlined. PBDC is an appropriate approach for the seismic assessment of this class of bridges, particularly if the damage is determined using a displacement-based assessment approach.

Wind barriers are nowadays commonly placed on bridges to protect vehicles from adverse cross-wind effects. In addition to this beneficial influence, wind barriers may adversely affect the bridge dynamic stability. This is particularly exhibited for long-span cable-supported bridges. It is therefore the scope of the present study to analyze the effects of wind barriers on aerodynamic and aeroelastic characteristics of bridge-deck sections of long-span cable-supported bridges together with the respective flow characteristics around bridge-deck sections. The focus is on various arrangements of wind barriers, i.e., (1) wind barriers placed at the windward bridge-deck edge only; (2) wind barriers placed at the leeward bridge-deck edge only; and (3) wind barriers placed at both windward and leeward bridge-deck edges. This was carried out experimentally on small-scale models in a boundary layer wind tunnel. Three typical bridge-deck section models were studied, i.e., Great Belt (Denmark), Kao-Pin Hsi (Taiwan), and Golden Gate (United States). The galloping susceptibility of the bridge-deck sections in all arrangements of wind barriers proved to be the same, as is the case for the empty bridge-deck sections without wind barriers; i.e., from this point of view, wind barriers do not adversely bridge dynamic stability. However, in configurations with the windward wind barrier only, as well as both windward and leeward wind barriers, the flutter susceptibility of the bridge-deck sections increases substantially; i.e., the critical flow velocity for the bridge flutter decreased significantly in comparison with the respective empty bridge-deck sections. For the leeward wind barrier only, the flutter susceptibility of the bridge-deck sections did not change and remained the same as it was for the empty bridge-deck sections. The empty bridge-deck sections do not exhibit any significant change concerning their susceptibility to flutter for various turbulence levels of the incoming freestream flow. The flutter susceptibility of cable-supported bridges equipped with wind barriers is lower in more turbulent incoming flows. The bridge decks with wind barriers are more resilient to flutter in more turbulent winds. Shear layers that separate from the top of the wind barrier may have an important role in the self-excited lift force and the pitch moment and, consequently, the dynamic behavior of bridge decks.

Ultra-high performance fiber reinforced cementitious (UHPFRC) and composite reinforcement techniques have great potential in achieving efficient structural resistance recovery and overall performance enhancement. The goal of this study is to confirm the reinforcement effectiveness by conducting test and analytical studies for three full-scale prestressed concrete hollow slab girders with insufficient bending capacity and stiffness. In this full-scale test study, four-point loading was adopted for one of the test girders before reinforcement to acquire the residual bending performance. Reinforcement measures were then carried out for all three test girders, including a composite concrete (or UHPFRC) layer for the top flange and a steel plate–concrete (or UHPFRC) composite reinforcement for the bottom flange, and bending tests were conducted after reinforcement. Based on the test results, simplified analytical models were developed and empirical equations were proposed for test girders after reinforcement. The present study has proved the effectiveness of UHPFRC and composited reinforcement measures in improving capacity, stiffness, and guarantee of durability comprehensively.

Bridge cables are often subjected to tensile stress variation, interior contact stress, and corrosion environment, resulting in premature failure of wires. This paper experimentally investigates the behavior of bridge wires under the coupled action of corrosion, fretting, and fatigue. A corrosion-fretting fatigue test system was developed, and its working principle and test method were introduced. Corrosion-fretting fatigue tests and comparison tests of cable wires with different test parameters were conducted based on the proposed test system. Damage process, fracture mechanism, friction coefficient, and lifetime of wires were further investigated. It is observed that the failure originated from micro surface cracks at the trailing edges due to morphology irregularity and tear stress. The crack propagation was dependent on the friction angle that affected the stress distribution in the contact area. During corrosion-fretting fatigue tests, corrosion facilitated the wear through damaging the wire surface and inner micro structure, and simultaneously fretting fatigue accelerated corrosion via promoting the contact between corrosive media and wires. Thus, the coupling scar can be even deeper than the sum of the fretting fatigue scar and corrosion pit. Larger friction angle and corrosion current aggravated failure and decreased the lifetime of wires.

Conventional designs for added damping in stay cables with a High Damping Rubber (HDR) damper are commonly carried out assuming perfect boundary conditions at the cable ends or a smooth transition between the damper and cable. This paper proposes an asymptotic formulation for the attainable damping in stay cables with an externally installed HDR damper that accounts for uncertain boundaries at the cable ends, which includes hinged, fixed, and rotational restraint ends. The results indicate that by adjusting supports at the cable ends with finite rotational restraint stiffness, the damper works more effectively. In addition, a reduction factor (R_rd) of the achievable damping caused by rotational restraint at an HDR damper location will be proposed and investigated for a clamped–clamped cable. In the design of an HDR damper with a rotational restraint between the damper and cable, the damping ratio is reidentified by multiplying the designed damping of a conventional case by the reduction factor (R_rd).

A partial-depth, diamond-shaped, ultra-high performance concrete (UHPC) connection with embedded transverse reinforcement between adjacent precast prestressed concrete voided beams (APPCVBs) has been developed by the Federal Highway Administration (FHWA) to overcome the disadvantages of longitudinal cracks within the connections. In this study, the shear behavior of 14 spliced panel specimens with the FHWA developed UHPC connection will be experimentally investigated. One monolithic specimen will be tested as a reference. The test parameters include surface preparation, the compressive strength of the filling concrete, lateral reinforcement details, and the lateral reinforcement diameter. The shear behavior will be evaluated from cracking patterns, failure modes, load–deflection responses, and ultimate load capacity. Formulas will be derived based on the elastic beam theory coupled with the dowel effect of transverse reinforcement. The derived formulas could generally predict the shear strength of the spliced panel specimens with the FHWA developed UHPC connection.

This paper studies the feasibility of replacing damaged deck of posttensioned concrete box-girder bridges without the use of falsework to support the superstructure span. Parameters of the study included straight, curved, and skewed bridges, and simple versus multispan bridges. Deck replacement in posttensioned box-girder bridges requires special attention because the deck forms an integral part of the load-resisting mechanism and large precompression has been locked in by the posttensioning in the superstructure. The potential unfavorable stress reversals or redistribution during deck replacement should be carefully considered. In this study, practical options for lane closure and traffic rerouting were incorporated into the replacement strategies, and these options included temporal longitudinal and transverse replacements. Additionally, time-dependent properties for concrete and steel representatives of current construction practice were included in the finite-element model. Results indicated that full-depth deck replacement may be difficult and undesirable because the current AASHTO stress limits were violated in all four of the posttensioned box-girder bridges selected for the study. Additionally, the increase in permanent deflections through deck replacement was relatively large for these selected bridges, which is likely to result in degraded ride quality, safety, and poor drainage condition for the bridge. As a general trend, critical stresses at the top of the web and downward deflection of the girders were found to accumulate as the deteriorated deck was removed and a new deck cast.

To enhance the structural performance and durability of a conventional reinforced concrete (RC) cover slab over a culvert as well as to improve its spanning ability, this paper presents a novel ultrahigh-performance concrete (UHPC)-RC composite cover slab with a clear span of 8 m. The inverted prefabricated UHPC single-Tee or double-Tee beam was placed at the bottom of the cast-in-place normal strength concrete to form the UHPC-RC composite cover slab. A full-scale experimental test on the UHPC-RC composite cover slab was conducted to explore and quantify its mechanical performance. The structural characteristics of the slab, such as failure mode, moment capacity, flexural stiffness, concrete strain distribution, and cracking behavior, were experimentally investigated. The results indicated that, compared to the conventional RC cover slab, the UHPC-RC composite cover slab exhibits a typical flexural failure with a higher cracking resistance, flexural stiffness, flexural capacity, and ability to restrain the propagation of the cracks. An optimized scheme is successfully applied to the practical project. Field testing during the construction process was conducted to investigate the flexural performance of the new composite structure. The results indicated that the structural behavior of the UHPC-RC cover slab aligned well with its predicted values, demonstrating the effectiveness and feasibility of using the UHPC-RC composite cover slab in practical engineering applications.