AbstractBecause of their large stiffness and spanning capability, continuous rigid frame arch bridges are attracting increasing interest in the development of high-speed railway networks in China. ...The internal loadings are associated with both the continuous rigid frame and arch substructural systems. Thus, the bridges are subjected to complex stresses, in particular, at the girder-arch-pier connections. The evaluation of the mechanical performance and understanding of the stress distribution of the girder-arch-pier connection are critical for ensuring the effective design and condition assessment of the bridges. This paper investigates the stress distributions in the girder-arch-pier connections of the world’s longest continuous rigid frame arch railway bridge, the Yichang Yangtze River Bridge. Two models with a length scale of 1/10 were prepared and tested for the side-span and midspan girder-arch-pier connections, respectively. Detailed stress distributions in the connection models were measured, and three-dimensional finite-element models were established to help understand the measured stress distributions. The side-span and midspan connections are primarily in compression and have similar stress distributions.
•Novel fragility models for scoured-critical bridges exposed to multiple hazards were generated•Rigorous FEM included the water-soil-bridge interaction under flooding and earthquakes•Failure modes ...for bridge components exposed to floods were described•Insights on the flood vulnerability of integral and bridges with bearings are provided•Consideration of uncertainties in scour formation enhance the reliability of risk assessment
Building resilient bridges, that are able to withstand multiple natural stressors with minimal damage and quickly restore their functionality is paramount to delivering climate-resilient transport infrastructure. Nevertheless, bridges are proven to be vulnerable to natural hazards, with floods and earthquakes being the main causes of failure. The available research and practice for assessing the vulnerability of river-crossing bridges is predominantly qualitative and therefore relies heavily on visual inspections, while ignoring important characteristics of the complex water-soil-bridge interaction. This is a knowledge gap that this paper aims to fill. This work provides novel fragility models for hydraulically induced stressors and/or combinations of hydraulic and seismic hazards. To achieve this, unique detailed two- and three- dimensional numerical models are employed, for a typical three-span prestressed box-girder river-crossing bridge. This paper is a primer on the vulnerability of flood-critical bridges as it models the entire water-soil-bridge system, taking into account critical hydraulic stressors (scour, debris accumulation, hydraulic forces), the uncertainty in scour hole formation, and all components of integral and isolated bridges: deck, bearings, piers and abutments, backfill, and the foundation soil. A detailed description of the damage modes for each component is given and sets of fragility curves for floods and combinations of hydraulic stressors and earthquakes are developed. The study concludes that integral bridges are in most cases more vulnerable to local scour than bridges with bearings, since the latter are more flexible and can therefore adapt to changes in their geometry. The opposite is true for global scour and/or seismic earthquake excitations. The generated fragility models are useful tools for quantitative risk assessment of transport systems and provide practical means in resilience-based asset management by owners and operators of transport infrastructure.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Introduce artificial neural network for regional seismic risk assessment of skewed bridges.•Develop multi-dimensional fragilities for California bridges via artificial neural network.•Reduce ...computational efforts for developing bridge-class fragility curves.•Estimate the seismic vulnerability of skewed bridges.
Recent researches are directed towards the regional seismic risk assessment of structures based on a bridge inventory analysis. The framework for traditional regional risk assessments consists of grouping the bridge classes and generating fragility relationships for each bridge class. However, identifying the bridge attributes that dictate the statistically different performances of bridges is often challenging. These attributes also vary depending on the demand parameter under consideration. This paper suggests a multi-parameter fragility methodology using artificial neural network to generate bridge-specific fragility curves without grouping the bridge classes. The proposed methodology helps identify the relative importance of each uncertain parameter on the fragility curves. Results from the case study of skewed box-girder bridges reveal that the ground motion intensity measure, span length, and column longitudinal reinforcement ratio have a significant influence on the seismic fragility of this bridge class.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Integral bridges are a class of bridges with integral or semi-integral abutments, designed without expansion joints in the bridge deck of the superstructure. The significance of an integral bridge ...design is that it avoids durability and recurring maintenance issues with bridge joints, and maybe bearings, which are prevalent in traditional bridges. Integral bridges are less costly to construct. They require less maintenance and therefore cause less traffic disruptions that incur socio-economic costs. As a consequence, integral bridges are becoming the first choice of bridge design for short-to-medium length bridges in many countries, including the UK, USA, Europe, Australia, New Zealand and many other Asian countries. However, integral bridge designs are not without challenges: issues that concern concrete creep, shrinkage, temperature effects, bridge skew, structural constraints, as well as soil–structure interactions are amplified in integral bridges. The increased cyclic soil–structure interactions between the bridge structure and soil will lead to adverse soil ratcheting and settlement bump at the bridge approach. If movements from bridge superstructures were also transferred to pile-supported substructures, there is a risk that the pile–soil interactions may lead to pile fatigue failure. These issues complicate the geotechnical aspects of integral bridges. The aim of this paper is to present a comprehensive review of current geotechnical design practices and the amelioration of soil–structure interactions of integral bridges.
Abstract
This paper introduces field tests of the first continuous multispan slab-on-girder bridge with hybrid glass fiber-reinforced-polymer (GFRP)–steel reinforcement in Canada. The bridge was ...constructed in 2012 on Chemin Dunant overpassing the extension of Highway 410 in Sherbrooke (Quebec). The bridge consists of three spans with a maximum span of 44.6 m and is a typical slab-on-girder bridge with three traffic lanes. The bridge cross section consists of five steel girders, 1.9-m depth, covered with a 200-mm-thick concrete slab. The deck slab was reinforced with hybrid GFRP–steel reinforcement with a top mat of GFRP bars and a bottom mat of galvanized-steel bars. The Ministry of Transportation of Quebec recommends using galvanized-steel bars instead of black-steel bars because the former has higher corrosion resistance. The amount of reinforcement was determined using the empirical design method based on a steel reinforcement ratio of 1.0% according to existing design codes . The bridge was examined under live-load field testing involving seven load cases of truck locations. The steel-girder deflection was measured, and the strains in the GFRP and steel bars over an intermediate bridge pier were recorded. The field test showed very low strains in the GFRP and steel bars. The visual field inspection over approximately 6.5 years revealed that the bridge performed well under normal traffic conditions, confirming the applicability of using hybrid reinforcement in continuous bridges. An analytical parametric study was conducted examining the effects of changing the top reinforcement bar diameter, top and bottom reinforcement spacing, the hybrid- or GFRP-reinforced deck slab, and the dimensions of the steel-girder cross section (noncompact). The study revealed that the empirical method is conservative and calls for an unreasonable amount of reinforcement. Accordingly, the flexural design method (sectional analysis) should be used for the negative moment section.
AbstractOverturning collapse has been regarded as one of the most critical failure modes for single-column-pier bridges in current practices. To reveal the entire overturning process, a meticulous ...three-dimensional (3D) simulation of bridges with superstructures, bearings, and piers, considering geometric and material nonlinearities, was first established. Multiple load patterns were applied, including the practical eccentric truckloads that lead to overturning incidents and the conventional checking loads that are defined in the bridge design specifications. Second, four sequential limit stages of the overturning process were defined to precisely describe the structural behaviors under different mechanical conditions before the final collapse. A safety indicator was further proposed to quantify the possibility of overturning with respect to different limit stages. Using such a safety indicator in a case study, the ability of bridges to resist overturning was assessed and compared to results from the specifications and field observations. By doing this, the drawbacks of specifications in checking the safety of single-column-pier bridges were demonstrated. A parametric study was finally conducted to investigate the influence of different single-column-pier bridge arrangements on the overturning behaviors. It can be concluded that the specification-based methods greatly overrate the safety level of single-column-pier bridges, whereas the safety indicator provides more reasonable results as well as multiple-sublevel safety warnings up to the final collapse. Additional findings and suggestions for a better design or maintenance of single-column-pier bridges in curved-girder cases were also discussed.
Abstract
Ultrahigh-performance concrete (UHPC) offers significant potential to address a variety of needs in bridge design, construction, and performance enhancement. Bridge owners have shown ...willingness to embrace novel solutions that could address specific challenges related to the cost, speed of construction, durability, and service life of their projects. There are hundreds of bridges worldwide that, largely in the past decade, have utilized UHPC. These applications range from minor field-cast closures to precast segments for long-span bridges to kilometer-long bridge deck overlays on a signature structure. The objective of this paper is to promote the application of this class of cementitious material in bridge engineering by presenting the progress that has been made in different regions of the world in the past two decades. Today, UHPC is being widely used in Malaysia to design and construct many bridges of different types and spans as they build out their roadway network. In South Korea, the unique characteristics of UHPC are being utilized to advance the state-of-the-art in long-span bridges. The French were early adopters and pioneers in building a strong foundation for using UHPC in a variety of bridge applications. In Switzerland, UHPC is employed to address major bridge rehabilitation needs. The United States bridge sector has embraced UHPC for a variety of field-cast connections. Current research and development efforts are promoting the use of UHPC in major rehabilitation projects and construction of primary bridge components. The adoption of UHPC solutions into the bridge sector is progressing rapidly because of the unique opportunities provided by the strength and durability of the material. It is expected that additional innovations and refinements of solutions will occur as knowledge of the material proliferates.
Buildings play an indispensable role in urban development. As typical structures of transportation buildings, bridges serve as crucial nodes in connecting different regions, promoting economic ...growth, and ensuring social security. However, with the extension of their service life, the performance of bridges will inevitably decline. Performance monitoring and evaluation are crucial during the life cycle of bridges. The accelerating convergence of civil engineering, materials science, and artificial intelligence has sparked the interest of researchers from different disciplines in the emerging field of bridge state perception. This reprint covers topics on condition monitoring and assessment of engineering structures, featuring 13 papers. These studies provide some novel methods, models, and technological applications for bridge condition perception, which are of great significance for the design, construction, and assessment of bridges.
PDF
