Journal of Bridge Engineering

This paper presents the findings of an experimental study that investigated the response properties of segmental cantilever columns incorporating internal unbonded posttensioning (PT) and slip-dominant (SD) joints. The SD joints exhibited controlled sliding that provided energy dissipation with low damage. All joints of these columns, except for the bottom one, were designed to be SD. The bottom joint was designed to be rocking dominant (RD) and exhibited rocking that offered self-centering to the system. Design objectives and equations are presented. These equations were used for the design of a large-scale cantilever column that was subjected to reverse lateral cyclic loading at its top end, reaching a maximum drift ratio of 14.9%. At small drift ratios ($\le 3\%$), the response was dominated by sliding of the SD joints that provided energy dissipation (damping). For medium drift ratios (between 3 and 10%), rocking at the bottom joint increased and provided self-centering properties to the system. For large drift ratios ($>10\%$), the self-centering properties decreased, but the damping properties remained practically constant. Rocking at the SD joints remained small at all times. Minor spalling was observed in the SD joints, while concrete crushing was observed at the bottom joint.

This paper proposes a new framework for predicting remaining bridge strength that integrates a Bayesian network and in situ load testing. It discusses the uncertainty of important factors on corrosion damage and develops a stiffness degradation model for corroded beams based on experimental investigations. Following this, the authors develop a Bayesian network that includes corrosion damage, stiffness degradation, load-deflection response, and other factors to predict structural strength degradation. A numerical example using an existing RC bridge demonstrates the general procedures. The comparison between the theoretical and the experimental deflections from load testing shows that the proposed methodology can efficiently improve prediction accuracy and reduce prediction uncertainty.

Numerous fatigue cracks were observed recently in orthotropic steel bridge decks that have been in service for a long period of time. A fatigue crack initiating from the rib-to-deck (RD) joint may especially produce asphalt surfacing damage, and hence have an impact on traffic safety. In fatigue evaluation of RD joints, in most current design specifications the asphalt surfacing is just treated as a layer dispersing wheel loads, in which the wheel loads are uniformly distributed on the deck plate and the effect of the composite stiffness of the deck plate and asphalt surfacing is neglected. In this study, comprehensive finite-element and load models were used to investigate the asphalt surfacing influence on the wheel load dispersal and composite stiffness. The analysis result shows that wheel loads are not uniformly distributed on deck plates but are concentrated on the weld joints, the asphalt surfacing could significantly decrease the stress magnitude around the RD joints, and this decrease may mainly result from composite stiffness rather than load dispersal. The effective stresses of RD joints, and their fatigue evaluation indicate that the fatigue life of RD joints could be drastically improved by asphalt surfacing. However, on the other hand, the fatigue life is shortened considerably by the effects of temperature. Moreover, the type of fatigue crack initiating from the weld root may also be influenced by the asphalt surfacing.

This paper investigates the use of glass fiber reinforced polymer (GFRP) bar bents as stirrups at the joint between the steel posts of a bridge guardrail system with a deck slab cantilever. In addition, GFRP bars with headed ends are used for better anchorage at the postdeck slab joint. Four full-scale cantilever post specimens were erected and tested to collapse. Two specimens were reinforced with steel bars as control specimens, whereas the other two specimens were reinforced with GFRP straight bars, bent bars, and headed bars at applicable locations. Similar failure modes were observed in all specimens because of curb external side face breakout. Failure occurred in unconfined concrete cover because of significant compressive and frictional shear stresses and also torsional effects, resulting in concrete spalling at the side face of the cantilever at the bottom of the posts. Although it is recommended to consider larger edge distance of the post to prevent premature failure in the unconfined concrete cover, the obtained experimental capacity of the postcurb region was concluded to be sufficient to resist design loads. To calculate the share of the design lateral loads received by each post, a linear finite-element analysis (FEA) and a simplified FEA were used. The analysis showed that the share of each post decreases with decrease in spacing between posts.

This paper focuses on studying numerically the cyclic behavior of RC bridge columns that are seismically retrofitted using thermally prestressed shape memory alloy (SMA) spirals, an innovative active confinement technique that has been validated experimentally. A fiber-based model of the actively confined column is first developed and is validated using experimental results. Comparing the numerical and experimental behaviors shows that the developed model is satisfactorily capable of describing the hysteretic behavior and damage states of the experimental column. The developed model is then used in a parametric study to investigate the effects of the interactions between active confinement pressure and other important design and geometrical parameters of the columns, such as axial load, volumetric ratio of longitudinal reinforcement, and slenderness ratio. The results of this parametric study provide practical information that is useful in setting a design guideline for retrofitted bridge columns using the newly developed SMA active confinement technique.

This paper presents extensive temperature measurements obtained during a period of 4 years in an integral solid slab prestressed concrete bridge deck. There is very little experimental information available for this bridge typology. The quality of the measured temperature data are validated by comparing experimentally measured displacements at the ends of the bridge with theoretical displacements determined with the recorded temperature components. The measured temperatures are also compared with common design parameters made considering the specifications for thermal actions proposed by Eurocode 1. The results corroborate that the Eurocode 1 formulations are generally adequate to represent thermal actions on bridges; however, it may need to be complemented to define maximum and minimum temperatures for bridges in locations with daily temperature variations greater than 10°C.

The local deformation mechanisms in steel monostrands have a significant influence on their fatigue life and failure mode. However, the observation and quantification of deformations in monostrands experiencing axial and transverse deformations is challenging because of their complex geometry, difficulties with the placement of strain gauges in the vicinity of the anchorage, and, most importantly, the relatively small magnitude of deformation occurring in the monostrand. This paper focuses on the measurement of localized deformations in high-strength steel monostrands using the digital image correlation (DIC) technique. The presented technique enables the measurement of individual wire strains along the length of the monostrand and also provides quantitative information on the relative movement between individual wires, leading to a more in-depth understanding of the underlying fatigue mechanisms. To validate the proposed image-based measurement method, two different tests were performed, with the one correlation method showing good agreement. Data collected from the DIC technique creates a basis for the analysis of the fretting and localized bending behavior of the monostrand and provides relevant information on the internal state of displacement of the monostrand under bending load.