Journal of Bridge Engineering

Bridge design values for axle load and truck volume have increased since the 1960s, following the introduction of modern vehicle configurations, such as those of permit, special hauling, and emergency vehicles. Many highway bridges in the U.S. are estimated to be structurally inadequate, especially with respect to the shear capacity of the superstructure to carry these loads, and there have been numerous efforts to consider strengthening options for such older shear-deficient bridges. Techniques for enhancing the shear capacity of concrete bridge girders range from traditional approaches using steel and concrete (e.g., bolted steel plates) to newer approaches that utilize novel concepts and advanced materials, such as fiber-reinforced polymer (FRP) composites and shape-memory alloys. This paper reviews these shear strengthening techniques from a practical application standpoint, particularly with respect to their structural efficiency and constructability. The conceptual basis of each technique is described along with a summary of the advantages and shortcomings of each technique, followed by an overview of some representative field implementations and relevant design guidelines, if available. Finally, the concept of developing an assessment rubric is introduced to aid in identifying a potential shear-strengthening scheme for a particular project.

Flexural continuity over the interior supports of steel girder bridges reduces the forces within the spans while creating negative moments at the supports. The negative moment creates tension at the top of the structure and can lead to a cracking of the deck near the piers, which then allows moisture and deicing chemicals to penetrate the slab, resulting in its degradation. One remedy is to create a state of precompression in the slab to reduce the size and extent of the cracking. The self-stressing system achieves this state of compression in a two-span bridge by constructing the bridge deck with the interior support raised. Once the slab has been cast and cured, the center support is lowered in the final position. Continuity of the steel member results in the development of compressive stresses within the slab in response to the lowering of the support. This initial compressive force counters the tensile stresses resulting from live load and prevents crack formation along with the associated deleterious effects. Experimental investigations were performed on both cast-in-place and precast specimens observing the time-dependent behavior and performance under ultimate loading. The results indicated that the system performed as expected and increased the level of load at which cracking of the deck occurred.

An accurate estimation of displacement demand is essential to predict structural performance. However, the calculated displacements will vary depending on the analysis procedure. This paper shows the differences between the seismic demands of reinforced concrete (RC) columns calculated by using three analysis procedures: (1) AASHTO Seismic Guide Specifications (SGS); (2) direct displacement–based assessment (DDBA); and (3) nonlinear time history analysis (NLTHA). The demands were evaluated using two different response spectra definitions (3-period and 22-period representations) of the 2018 USGS seismic hazard model for structures located in shallow crustal and subduction tectonic regimes. Nonlinear time history analyses were performed using spectrally matched records for five design spectra from both tectonic regimes. This paper shows that the AASHTO-SGS significantly underpredicts the demands (compared with NLTHA) as the displacement ductility increases. In contrast, the predictions of the DDBA agree well with those of NLTHA, with mean differences of 10% for ductility higher than μ_Δ = 3. Lastly, equations are proposed to improve the accuracy of displacement demands for the AASHTO-SGS and the DDBA methodologies.

Bridges in earthquake-prone states like California have been studied for near-field and far-field loadings. However, there is a research gap in terms of how an earthquake of a certain strike, dip, and rake is going to influence the bridge response. Here, we focus on multispan continuous concrete single-frame box girder bridges. In this study, we simulate earthquakes of varying focal mechanisms and perform nonlinear dynamic analysis of bridges with the synthesized ground motion. Furthermore, the influence of azimuth orientation with respect to the source is studied by placing the bridge model a few kilometers from the source at certain azimuths motivated by the radiation pattern of seismic waves. Fixing a magnitude, depth, and reference focal mechanism angles determining a focal mechanism is varied to study the effect of strike, dip, and rake on the bridges. In each of these cases, the potential risk is identified, and the study underscores the need to include these focal mechanism parameters into bridge fragility computations in risk assessment platforms such as HAZUS.

Composite box girders with corrugated steel webs (CBGCSWs) are used worldwide owing to their light self-weight, high efficiency of prestressing application, and reasonable distribution of shear force and bending moment. An improved composite box girder with corrugated steel webs (ICBGCSWs) has been recently introduced to further reduce the dead weight and improve its durability. Because the innovative ICBGCSW has emerged as a new structure, very few studies have been conducted on its dynamic characteristics. In the present study, a theoretical analysis was first conducted. By comprehensively considering the shear lag effect and the shear deformation of CSWs, the element stiffness matrix of ICBGCSW was derived based on the principle of stationary potential energy. The natural frequencies and mode shapes in vertical bending vibration were calculated via a self-developed software program. The proposed method was verified by comparing the results with finite-element analysis and experimental results. Then, sensitivity studies were performed to investigate the influences of the shear lag and shear deformation on the natural frequencies of vertical bending vibration. Finally, vibration frequencies of the continuous ICBGCSW were calculated, and a general formula for calculating the fundamental frequency of simply supported girders, continuous girders with equal spans, and continuous girders with unequal spans was proposed. The proposed method, being able to consider both the effects of shear lag and shear deformation of the box girder, delivered very good performance in studying the dynamic characteristics of the ICBGCSW, whereas the proposed general formula of fundamental frequency could serve as a good reference for the bridge design in practice.

Underdeck cable-stayed bridges have recently been shown as one of the promising bridge types due to their multiple advantages such as high structural efficiency, elegant appearance, and economy. The stay cables located under the deck not only introduce axial compression to the deck but also provide additional support to it. Both the ductility and ultimate load should be carefully examined in the design, which requires the estimation of full-range behavior. To predict the full-range behavior considering the material and geometric nonlinearity of underdeck cable-stayed bridges with prestressed concrete decks, an analytical beam model and its corresponding beam finite-element model are developed. The model adopts the actual stress–strain relationships of materials and can take into account the interaction between the flexural and axial deformations of the deck. In the structural system, the interaction between the stay cables and the deck is taken into account employing nonlinear kinematical theory. The analytical model is verified against experimental results. Numerical examples are given not only for illustration but also for investigation of various parameters governing the ultimate load and ductility.

Piles driven in Intermediate GeoMaterials (IGM) have possessed many design and construction challenges due to high uncertainty in the engineering properties of IGM, absence of geomaterial classification and static analysis (SA) methods, inadequate Load and Resistance Factor Design (LRFD) recommendations, and lacking knowledge on the change in pile resistances with time. This paper presents our recent development and recommendations for piles driven in fine-grained soil-based IGM (FG-IGM) based on 51 test piles from 25 bridge projects completed in four US states. FG-IGM is categorized into clay-IGM and silt-IGM based on grain size and plasticity. A classification boundary between fine-grained soil and FG-IGM is established at undrained shear strength (s_u) of 0.129 MPa (2.7 ksf). SA methods for unit shaft resistance (q_s) are recommended based on s_u while SA methods for unit end bearing (q_b) are established using the combination of s_u, pile size (D), and total pile penetration (D_B). The proposed SA methods are compared against the existing α-methods developed for soil and validated using 33 independent test pile data. Our statistical assessment concludes that the proposed SA methods provide a more accurate estimation of q_s and q_b than the α-method. Higher LRFD resistance factors and efficiency factors are determined for the proposed SA methods than for those developed for fine-grained soils. For 1 day after the end of driving (EOD), an average 77% and 44% increase in q_s can be considered for steel H-piles in clay-IGM and silt-IGM, respectively, while a higher average 132% increase in q_s can be considered for 360-mm close-ended pipe piles in clay-IGM. However, pile setup should be neglected in the q_b prediction as H-piles experienced both pile setup and relaxation with the percent change in q_b varying from −23% to 345% in clay-IGM and −33%–22% in silt-IGM, and 360-mm close-ended pipe piles experienced −51%–202% change in q_b.

Current bridge codes in the US, Europe, and China specify vehicular collision loads for the design of piers. However, the performance of piers designed according to current codes in the three countries or regions is unknown yet. This paper presents a performance evaluation of concrete-filled steel tubular (CFST) piers subjected to vehicle collision. Before the evaluation, bridge specimens with a single CFST pier were designed in accordance with current bridge and structural codes in the three countries or regions, respectively. Then, a detailed finite-element (FE) model for simulating a truck collision with a CFST pier was developed and validated. By comparison with seven simplified FE models, the detailed FE model was further confirmed to be employed for the evaluation. In the evaluation, the effects of current codes in the three countries or regions, whether or not the vehicular collision load is considered, two pier heights (i.e., 6 and 12 m), two truck weights (i.e., 20 and 40 tons), and three impact speeds (i.e., 60, 100, and 140 km/h) on the performance of CFST piers were investigated. The evaluation results indicated that when a CFST pier in seismic zones is designed to resist vehicle collision according to current codes in the US and China, it only needs to meet the requirements of seismic design without additional consideration of the vehicular collision load. Moreover, a preliminary application condition should be added for the vehicular collision load specified by the current bridge code in Europe, that is, when the truck weight is more than 20 tons and/or the pier height is lower than 12 m.

Shale is a transition material harder than soil and softer than hard rock. Treating shale as soil-like material in the Wave Equation Analysis Program (WEAP) could result in several construction challenges such as early pile refusal and pile damage. To overcome these limitations, this paper presents the development of improved WEAP methods for steel H-piles driven in shale including load and resistance factor design (LRFD) recommendations. Our parametric study reveals a significant effect of damping factors of shale on the bearing graph analysis and the determination of ultimate pile resistance. Using load test data of 32 steel H-test piles driven onto shale in Kansas, a back-calculation procedure was adopted to yield recommended dynamic parameters for shale, which are incorporated into two proposed WEAP methods. A range of damping factors from 0.03 to 0.97 s/m are recommended for two proposed WEAP methods, shale types, and weathering conditions. The accuracy and efficiency of the proposed methods and default WEAP method were validated and compared using 44 dynamic load test results and data of 2 static pile load tests at the end of driving. Furthermore, 49 dynamic test results at the beginning of restrike condition were also used for comparison. The LRFD resistance and efficiency factors were calibrated for the three WEAP methods for analyzing shale pile resistances. An economic study reveals that the three WEAP methods, on average, overpredict the weight of steel pile per load demand ranging from −0.01 to −0.05 kg/kN. Among the three methods, the proposed WEAP-UW-R will yield the least excess steel weight, on average, during construction, which will alleviate construction challenges encountered in the current practice, such as higher construction costs and longer durations.

Rubber-based seismic isolation has been demonstrated to be one of the most effective measures to protect structural elements from damage during earthquakes and a viable option to retrofit existing structures with poor seismic detailing. The main constituent of these isolation units is rubber, a material that is subject to stiffening when exposed to low air temperatures. In the case of isolated highway bridges, thermal stiffening might reduce the efficiency of isolators, transferring higher forces to the substructure. Assessment of the seismic response of retrofitted structures using rubber isolators in cold regions is thus necessary. Accordingly, in this study, the effect of low temperatures on the seismic performance of a highway bridge retrofitted with natural rubber (NR) isolators is quantified using a probabilistic framework based on fragility surfaces. From the component- and system-level surfaces, it is revealed that the effects of cold temperatures on highway bridges retrofitted with elastomeric isolators may be negligible, depending on the configuration of lateral restraining structures. However, when isolators are able to perform their function without impediment, their thermal stiffening might be significantly detrimental to the bridge’s substructure, mainly affecting bent columns.

For bridges susceptible to barge collision, design provisions are typically utilized in determining collision scenarios and impact loading. Provisions in the United States require that bridges be designed to withstand two distinct collision events: direct (head-on) and glancing (e.g., oblique side). Head-on impact scenarios are represented using empirically determined static loads, and perpendicular impact loads are applied with magnitudes assumed equal to 50% of head-on impact loads. Subsequent to the formation of these provisions, numerous studies have identified the need to account for dynamic phenomena when designing bridges to resist vessel collision loads. Further, design-oriented computational techniques have been developed to characterize representative vessel–bridge collision scenarios, quantify dynamic barge impact loads, and compute time-varying bridge responses. While previous studies focused on head-on barge–bridge collision, the current study characterizes oblique side barge impact loading and resulting bridge response. Parameters such as barge flotilla configuration, impact angle, and location of impact initiation are investigated across a range of bridge models, leading to the identification of design-relevant oblique side impact scenarios. An alternative to the 50% design approach for oblique side impact scenarios involving the corners of barge bows is then proposed for assessing overall stability. The proposed approach incorporates dynamic phenomena and maintains agreement relative to more detailed analyses.

This paper proposes an equivalent plane algorithm of spatial stay cables using spatial rigid arms and the stay cable corotational coordinate system. The equivalent equations for the cable displacements and force elements are established, and the equivalent plane-element stiffness matrix of the spatial-cable element and its transfer matrix are derived. The matrix is automatically transformed into the plane-cable element model with rigid arm when the cable plane of the cable-stayed bridge is parallel. The spatial characteristic parameters of the cable plane are proposed, and the spatial effect of the spatial-cable plane on the internal force and deformation of the cable-stayed bridge is also analyzed. This equivalent plane algorithm is programmed into the bridge design and construction monitoring system procedure, and a comparison analysis with MIDAS software is also conducted. The proposed method can simplify the calculation model for the entire construction process of cable-stayed bridges with spatial cables and yield a good calculation accuracy. The equivalent plane algorithm has been successfully applied to the Jiayu Yangtze River Bridge (a kilometer-scale cable-stayed bridge). The results show that the number of stay-cable elements in the calculation model is reduced by 50%. The difference between the proposed method and the calculation result of a spatial-cable plane model is very small for a cable-stayed bridge with a spatial-cable plane, whether the initial tension is used or an unstressed cable is used. The proposed method provides an efficient and reliable calculation method for the design and construction of spatial-cable-stayed bridges.

Bridges are an integral part of a country’s transportation infrastructure system. Earthquake-induced damages to bridges could result in fatalities and injuries, disturbances to the transportation infrastructure system, and incur significant repair costs. Furthermore, bridges must stay functional following an earthquake to maintain the continuity of transportation. Thus, innovative high-performance materials in the critical regions of structures and/or structural systems must be used located in regions of high seismic activity to mitigate the impacts of earthquakes. Despite having a higher seismic resilience, these structures, in general, tend to require a greater capital investment as a result of utilizing expensive material and special workmanship. However, when accounting for the postearthquake repair and maintenance costs, these seismically enhanced bridges can deliver significant cost advantages over conventional structures in the long run. Even so, the outcomes depend on the frequency and severity of the seismic damage, the lifespan of the bridge, the cost of materials, and the embodied emissions of the structures. To ensure better overall results, the cost–benefit analysis should be done with a life-cycle thinking perspective when comparing and making a decision related to multiple bridge systems. In this regard, a decision framework is developed to evaluate the overall life cycle performance of such a novel bridge, using fuzzy logic to integrate uncertainty. The proposed framework will assist engineers and the construction industry as a whole in making informed decisions regarding bridge infrastructure planning under dynamic conditions.

Bridges reinforced with superelastic shape memory alloys (SMAs) demonstrate improved performance under earthquake excitations. In general, the capital investment for a bridge reinforced with SMAs is higher due to their high cost and special workmanship requirement. However, when accounting for postearthquake repair and maintenance costs and environmental impacts, SMA-reinforced bridges can deliver significant economic and environmental advantages over conventional structures in the long run. Based on a life cycle thinking–based decision support framework developed in a companion paper, this study thoroughly evaluated the life cycle seismic performance of a bridge reinforced with an SMA considering three different reinforcement configurations. Fragility analyses were conducted for each reinforcement configuration of the SMA-reinforced concrete (RC) bridge to assess its seismic vulnerability. A life cycle cost (LCC) assessment was performed to determine the economic impacts during their service life. Additionally, cradle-to-grave life cycle assessment (LCA) was done using SimaPro to assess the environmental impacts. Using the outcomes of the these assessments, the overall life cycle performance of the novel bridges was compared with a similar bridge reinforced with conventional steel. The results showed that the SMA-reinforced bridges presented a better seismic life cycle performance compared with a conventional RC bridge from a seismic performance and economic perspective. However, the conventional bridge showed a better overall score from an eco-friendly approach.

Periodic bridge deck inspection is critically important in bridge management and maintenance. This paper presents a comprehensive bridge deck evaluation using sub-mm three-dimensional (3D) laser imaging technology in a nondestructive and efficient manner at highway speeds with complete lane coverage. A total of 58 bridge decks in Oklahoma were evaluated via Pave3D 8K system and 3D Safety Sensor. The Pave3D 8K system collected both 0.5-mm 3D height images, 2D grayscale images, and longitudinal profiler at highway speeds for bridge deck assessment in terms of distress detection and roughness evaluation. A Deep Learning-based method was applied to detect cracks automatically, and a manual tool was developed to label other distress for bridge decks and joints from the obtained images. Further, the 0.5-mm 3D images and longitudinal profiler data were combined to identify locations with roughness issues and the causes on bridge decks or approach slabs. Finally, the 3D Safety Sensor acquired 0.1-mm 2D/3D images for hydroplaning speed prediction of bridge decks. The evaluation results demonstrate the efficacy of the sub-mm 3D laser imaging technology for nondestructive bridge deck conditions and safety evaluations.

Twenty-five reinforced concrete (RC) columns of section size 250 × 250 mm were designed and tested to study the seismic response considering the effect of loading case, strengthening method, and the predamage level, containing 21 columns reinforced with high-performance ferrocement laminate (HPFL)-bonded steel plates (BSPs), i.e., the intact strengthened columns (ISCs), earthquake-damaged strengthened columns (EDSCs), corrosion-damaged strengthened columns (CSCs) and coupled-predamaged strengthened columns (CPSCs). The bearing capacity of the specimens under the four different types of loading methods is ranked as follows: uniaxial compression–bending–shear (CBS) members, biaxial CBS members, biaxial CBS-torsion (CBST) members, and uniaxial CBST members. Compared with nonstrengthened specimens, the cracks of the strengthened RC columns are more fully developed, and the failure modes have been changed after strengthening. The failure modes and load–deformation curves had little significant difference for the strengthened RC columns with different damage under combined loading levels. The bearing capacity of strengthened RC columns with the applied loading of 400 kN improved, which increased to 60.1%–114.7%, 29.9%–103%, 65.2%–127%, and 49.2%–104.5% for ISCs, EDSCs, CSCs, and CPSCs, respectively. Moreover, the bearing capacity of specimens decreased due to the existence of horizontal eccentricity. Finally, based on the degraded trilinear restoring force model, the strengthened influence coefficient for loading α and displacement β and the torsion influence coefficient for loading γ and displacement ξ were introduced. A modified restoring force model of RC columns was presented, reflecting the loading method, predamage level, and strengthening method. The theoretical calculation values align with the test load–deformation curves, and the mean absolute error is almost less than 15%.

Trains with a different number of carriages can induce stress responses with varying amplitudes in the long-span steel bridges, which consequently cause different levels of fatigue damage. To better evaluate the fatigue life of bridges, it is important to obtain the volume and types of different trains running on bridges. To overcome errors in identifying the different trains caused by electronic noise and, to more efficiently utilize machine learning techniques, the original train weigh-in-motion (WIM) time series are encoded into images. Subsequently, a support vector machine (SVM) based approach is proposed to classify trains with a different number of carriages. The method is divided into three steps: data conversion for image preprocessing, feature extraction for machine learning, and train category classification with SVM. In the image preprocessing step, the time history of the WIM train passing data is saved into image format. In the feature extraction step, the Histogram of Oriented Gradients (HOG) is obtained in row vectors for each image as input for machine learning. In the train carriage classification step, SVM is adopted as the machine learning model to predict different train types. To verify the proposed approach, train WIM data from the structural health monitoring (SHM) system of a suspension bridge are employed, and an accuracy of 97.5% is achieved in the classification of trains when considering noisy datasets. Compared with other state-of-the-art machine learning algorithms, i.e., AdaBoost, K-Nearest Neighbor (KNN), and Linear Classification (LC) Model, the SVM leads to the highest prediction accuracy and shortest computation time.