Journal of Bridge Engineering

Bidirectional shake-table tests were performed on two types of relatively large two-span continuous elevated-girder bridge models. One was supported on thin-walled hollow steel (HT) piers, and the other was supported on concrete-filled tubular (CFT) piers. The CFT piers were made by filling the hollow columns of the HT piers with normal concrete. One objective of the shake-table tests was to acquire basic data to establish an advanced seismic design method of the HT and CFT piers under bidirectional horizontal seismic accelerations, considering the interaction between the piers, rubber bearings, and a superstructure. The other objective was to experimentally confirm the effectiveness of upgrading the elevated-girder bridges with the HT piers by using CFT piers. It was shown by the present tests that the ultimate state of the respective HT piers in the bridge model was predicted reasonably well by the interaction equation expressed in terms of the multiaxial force and moment components acting at the top of the columns. As soon as all the piers reached their ultimate states, the entire physical bridge model with the HT piers started to collapse in the transverse (TR) direction. Because of the load redistribution between the HT piers in the bridge model during the shake-table test, the energy dissipation capacity of the piers increased considerably compared with that evaluated by the conventional shake-table test on single cantilever column models with a mass fixed to their top. The physical bridge model with the CFT piers exhibited an excellently upgraded seismic performance (i.e., small local buckling deformations of the piers and negligibly small residual sway displacements of the bridge system) despite the increased input acceleration wave with an amplitude 1.5 times larger than that used for the physical bridge model with the HT piers. This upgraded performance of the CFT piers was due to their enhanced energy dissipation capacity and unique local buckling restraining and/or restoring behavior.

A critical challenge in bridge design and the construction process is to reduce the weight of the bridge deck. Specifically, in small aged bridges, light modules provide an easy and fast bridge deck renewal. Sandwich panels were introduced as such lightweight bridge decks a few decades ago. Low density and high specific strength of the panels provide remarkable advantages for a wide variety of industrial applications. The objective of this study was to investigate the effect of geometric parameters on the mechanical behavior (deflection and shear force) of a corrugated-core steel sandwich panel and predict its response by developing mathematical regression models. The results reveal that the core and the face sheet thicknesses highly affect the panel deflection response, whereas the weld spacing has the highest contribution to the maximum shear force response.

A new concept was developed to accelerate the construction of highway bridge bents, to improve their seismic resilience, and to make them more durable. On-site construction activities are accelerated by precasting the columns and cap beams and by using socket connections at the bottoms of the columns and grouted connections at the top. Unbonded pretensioning of the columns increases both the bridge’s seismic resilience (through improved recentering) and its durability (through reduced cracking), whereas precasting improves quality control. Previous researchers have incorporated unbonded posttensioning into structural systems to reduce postearthquake residual displacements, but pretensioning is preferable in terms of construction convenience, speed, and quality control. Epoxy coating also adds corrosion resistance to the pretensioned strands. Two cantilever concrete subassemblies, representing the top and bottom connections for a column, were subjected to constant axial load and cyclic lateral loading. The tests demonstrated that the new system recenters better than does a comparable RC column. Furthermore, the inelastic action was restricted to the columns, thereby validating the capacity protection of the connection regions.

This paper presents an experimental investigation of the degradation of the mechanical behavior of corroded prestressing wires under high-cycle fatigue loading. To quantify the influence of corrosion degree, stress range, and loading cycles on the wires’ mechanical properties, static tensile tests were performed on corroded prestressing wires with a predetermined fatigue-loading history. It was observed that after high-cycle fatigue loading, all corroded prestressing wires failed around corrosion pits as a result of uneven corrosion. The fracture surfaces no longer presented a cup-and-cone pattern, and the shear lip disappeared. The ductility of prestressing wires is very sensitive to high-cycle fatigue loading and corrosion. The postyield branch became dramatically shorter and even disappeared with increased corrosion degrees and loading cycles. With the increased degrees of corrosion and loading cycles, a significant reduction was found in the ultimate strength and ultimate strain of corroded prestressing wires, with little effect on effective elastic stiffness. The theoretical degradation models of the ultimate strength and ultimate strain were established for corroded prestressing wires subject to high-cycle fatigue loading and were found to be in good agreement with experimental results.

In recent years, ultrahigh-performance concrete (UHPC) has been increasingly applied to orthotropic steel deck (OSD) bridges. The UHPC layer and the OSD are connected through short-headed studs. This paper studies the static and fatigue behavior of short-headed studs embedded in UHPC. Seven specimens were fabricated for push-out tests, three of which were subjected to static tests, and the other four were subjected to fatigue tests. The headed studs in these specimens had a low height-to-diameter ratio of 2.7. Both the static and fatigue tests showed that the specimens failed because of the fracture of the headed studs, whereas the UHPC layer did not develop appreciable damage. These observations reflected the fact that the short-headed studs developed full strength when embedded in UHPC. Based on the fatigue test results, a design S-N curve with 95% survival probability was proposed.

The design of modern bridge towers tends toward more and more complex-shaped (tapered and/or inclined cantilevers, etc.) and lighter structures. Consequently, the wind effects are often assessed through full-aeroelastic tests, even for small/medium-span flexible bridges. The lightness of these structures, together with a bluff shape, give rise to a certain susceptibility to vortex-induced vibrations (VIVs), which cannot be assessed by using simple sectional models due to the nonnegligible tridimensionality of the main phenomena involved. This paper deals with the VIV of a yawed and tapered tower of a 110-m-span cable-stayed road bridge in the South of Italy. The VIV response in smooth and turbulent flow estimated through a full-aeroelastic model is compared with those of two sectional models referring to two different cross sections along the height of the tower. The comparison shows that the predictions of the two sectional models significantly overestimate the drag force of the entire structure and underestimate the VIV response of the tridimensional model by a factor of two, confirming the previously mentioned need for full-aeroelastic tests. The work also gives some insight into the issue of scaling to prototype the sectional model results through the introduction of a modified modal shape factor. Finally, wake measurements in smooth and turbulent flow, together with flow visualizations by means of woolen yarns attached to the tower, shed some light on the complex flow past yawed bluff bodies.

Adjacent precast prestressed concrete box-beam bridges have been used in the United States for many years and have performed well. However, the shear keys between adjacent box beams are susceptible to cracking, which can cause reflective cracks in an overlay or composite deck. The shear-key cracks have been observed shortly after casting and have developed as a result of thermal load, shrinkage, live load, or a combination of these factors. Little research has been done to investigate the early-age field behavior of these bridges. In this study, the early-age behavior of a bridge containing partial-depth shear keys grouted with ultra-high-performance concrete (UHPC) and equally spaced dowel bars was investigated. The bridge, which is the first adjacent box-beam bridge in the United States utilizing reinforced UHPC shear keys, was instrumented and monitored. This paper presents the early-age field results of the bridge during the first week after construction. The bridge performed well, with no cracking in the shear keys based on field observations and data analysis. Furthermore, it is shown that the transverse dowels play a role in helping to carry the transverse stresses in the key at the early age, before the UHPC has gained sufficient strength.

Multispan continuous bridges have been widely used in navigable waterways. However, their susceptibility to progressive collapse as a result of vessel collision is not yet fully understood. Experimental studies of bridge collapses induced by vessel collision are costly, time-consuming, and often not feasible. This paper presents a numerical study on the progressive collapse of a multispan continuous bridge subjected to vessel collision. A high-fidelity finite-element model of a 14-span continuous bridge, including its prestressed concrete (PC) superstructures and reinforced concrete (RC) pier columns/piles, and the colliding barge was developed to investigate the bridge failure mechanism. The validation was carried out for PC superstructures and RC structural members of the bridge piers by using available drop-weight impact tests of PC and RC beams. Furthermore, evaluation of available forensic investigation data, such as photographs and a survey of collapsed spans/piers, indicated that the progressive collapse was well predicted by the numerical analysis. Results show that the bridge pier directly impacted by a vessel will fail in the lateral direction of the bridge span, whereas nonimpacted piers will fail in the longitudinal direction of the bridge span. Results also show that the number of collapsed spans/piers depends on underwater terrain conditions and that the failure of the slender pier columns and piles results from plastic-hinge bending.

On August 28, 2011, Tropical Storm Irene hit the state of Vermont with a severity that deposited 100–200 mm (4–8 in.) of rain across the state and resulted in damage or failure of over 300 bridges. The analysis of available data sets helped identify a set of 313 bridges (with a span greater than 6 m) damaged in a single state from a single extreme flood event that caused a 12-h rainfall recurrence interval that exceeded 500 years in some areas and 100 years throughout most of the affected areas. Based on available damage reports and photographs, the observed bridge damage was grouped into four levels of severity. This paper links watershed stream power to the observed bridge damage, develops a process for quantifying the hazard at bridges both as a case study and for future storms, and uses stream power as a hazard metric to produce probabilistic predictions of bridge vulnerability. The analysis also offers a comparison between damaged bridges and bridges that were not damaged in Tropical Storm Irene. Specific stream power (SSP) and the event-based Irene-specific stream power (ISSP) were computed and found to be both statistically significant at discriminating between damaged and nondamaged bridges, as well as between damage levels. The application of the empirical fragility curve analysis for SSP and ISSP produces a probability of damage generated from the results collected from Tropical Storm Irene. Spatially mapping the bridge-damage probability from an extreme event like Tropical Storm Irene enables the hazard to be effectively displayed over a broad range of scales (e.g., stream reaches, select watershed, statewide). The methodology presented here can be applied to other geographic settings and storm events of interest, and to the best of the authors’ knowledge, this is the first investigation comparing site-specific stream power to observed bridge damage at a network level.

This paper presents data from fiber-optic strain monitoring of the Nine Wells Bridge, which is a three-span, pretensioned, prestressed concrete beam-and-slab bridge located in Cambridgeshire in the United Kingdom. The original deployment at the site and the challenges associated with collecting distributed strain data using the Brillouin optical time domain reflectometry (BOTDR) technique are described. In particular, construction and deployment issues of fiber robustness and temperature effects are highlighted. The challenges of interpreting the collected data as well as the potential value of information that may be obtained are discussed. Challenges involved with relating measurements to the expected levels of prestress, including the effects due to debonding, creep, and shrinkage, are discussed and analyzed. This paper provides an opportunity to study whether two commonly used models for creep and shrinkage, adequately model data collected in field conditions.

Rational and precise evaluation for ultimate flexural capacity is essential for accurate prediction of the safety margin and overload capacity of existing bridges. One of the spans of a 28- year-old distressed simply supported T-girder bridge with a span of 20 m was severely damaged, and the decision to replace it with new one was made. A field destructive load test of this distressed span was performed. A nonlinear finite-element model technique was used to predict the failure load and retrace the load-versus-deflection response. The ultimate flexural capacity obtained by the destructive load test was compared with the results of a limit-states design method. The comparison revealed that the ultimate flexural capacity of the distressed bridge was more than the bending moment produced by the combined effect of self-weight and overloaded vehicles plying over it, which explains why the bridge supported overloaded vehicles for many years.