Performance Of Deck Research Articles

Understanding the performance of bridge decks through full-scale accelerated testing

Understanding the long-term performance of bridges plays a major role in the selection of appropriate asset-management strategies, which eventually reduce life-cycle costs and extend the service life of a bridge. To understand bridge performance better, the Federal Highway Administration initiated a research project utilising accelerated testing of full-scale bridge superstructure systems subjected to cyclic moving wheel loads and freeze–thaw environmental conditions. As part of the research project, complementary non-destructive evaluation (NDE) techniques were used to assess the performance of a full-scale bridge deck during the curing and loading period. NDE results, shortly after construction, revealed a smaller cover depth of rebars in the middle section of the deck. This has likely created a preferential path for the subsequent deterioration of the deck. It was suggested to use a scaled version of the electrical resistivity (ER) values to improve the consistency between temporal ER measurements of the deck, and it was shown that combining construction information with NDE results can improve the interpretation of results. Overall, the results showed the importance of NDE for quality assurance of new construction and provided a better understating of the long-term bridge deck performance.

Environmental life cycle assessment of bridge deck pavement and case studies of two bridges in China

The durability of deck pavement material has great impact on deck performance and carbon emission. This paper aims to analyze the durability of different deck pavement materials and structures by taking two bridges across the Yangtze River in China as examples, and establish the carbon emission model of the bridge deck pavement during the whole life cycle. The carbon emissions of the two bridges during twenty years of service are then calculated based on the model. It can provide reference for future bridge deck pavement schemes and measures to reduce carbon emissions. In this paper, two typical representative bridges in Jiangsu Province in East China are selected for case analysis, namely the Jiangyin Yangtze River Highway Bridge and the Second Nanjing Yangtze River Bridge. Firstly, this paper introduces the specific forms of various bridge deck pavement schemes since the construction of the two bridges. After many years of experiments, the pavement of the Jiangyin Yangtze River Highway Bridge has changed from mastic asphalt mixture to double-layer hot mix epoxy asphalt concrete, and that of the Second Nanjing Yangtze River Bridge has changed from warm mix epoxy asphalt to hot mix epoxy asphalt. Focusing on the carbon emission of bridge deck pavement, the carbon emission model of different asphalt mixture pavements based on life cycle assessment (LCA) is established. The assessment can be divided into five stages: material production, transportation, construction, maintenance and demolishment. This paper takes extra traffic congestion during repair and maintenance into consideration. In this paper, two bridges were taken as cases to calculate the carbon emission. In initial construction, the deck of the Jiangyin Yangtze River Highway Bridge was paved with mastic asphalt mixture; while the deck of the Second Nanjing Yangtze River Bridge was paved with epoxy asphalt concrete. The paving material of the Jiangyin Yangtze River Highway Bridge was changed into epoxy asphalt concrete gradually in repair and maintenance. The analysis results show that in the initial 20 years of life, considering the initial construction and major maintenance of deck pavement, the total carbon emission of the Jiangyin Yangtze River Highway Bridge and the Second Nanjing Yangtze River Bridge is 179,195 kg CO2e and 101,577 kg CO2e respectively. The unit carbon emission of the Jiangyin Yangtze River Highway Bridge after 20 years of opening to traffic is 5.079 kg/m2 CO2e. The proportions of the five stages were 76.4 %, 2.7 %, 2.5 %, 16.8 % and 1.6 %, respectively. The unit carbon emission of the Second Nanjing Yangtze River Bridge after 20 years of opening to traffic is 3.352 kg/m2 CO2e. The proportions of the five stages were 66.3 %, 2.4 %, 2.6 %, 28.2 % and 0.6 %, respectively. The results show that epoxy asphalt material has better durability and can reduce carbon emission of bridge deck pavement.

Flexural Performance and Design of Steel-UHTCC Composite Bridge Decks with Different Composite Degrees under Hogging Moments

Due to the excellent tensile properties and long-term durability, using ultrahigh-toughness cementitious composite (UHTCC) at the hogging moment regions of long-span composite bridge decks is a new solution to the cracking issue. Composite degrees and the longitudinal reinforcement ratio have been suspected of influencing the flexural performance of steel-UHTCC composite bridge decks under hogging moments, but the extent of the influence remains unclear. This study aims to investigate the influence of these two core design parameters. Six specimens with different stud spacings and longitudinal reinforcement ratios were designed to investigate the failure modes, flexural capacity, deformation behavior, and cracking characteristics. The results show that the cracking stresses σ0.05 and σ0.1 in the steel-UHTCC composite bridge decks were 58.6%–216.8% and 58.9%–213.5% higher than those in the steel-normal-strength concrete (NSC) composite bridge decks. As the longitudinal reinforcement spacing reduced from 125 to 75 mm, the growth of the crack width was effectively restrained, and the cracking stresses σ0.05 and σ0.1 increased by 36.6% and 71.2%, respectively. Finally, a modified theoretical model is established to evaluate the influence of composite degrees on the elastic flexural performance of steel-UHTCC composite bridge decks. The dimensionless composite degree η is defined as a core parameter in this model. For practical elastic design, the threshold value of the dimensionless composite degree can be determined as 0.005.

Structural performance of orthotropic Steel-Concrete continuous composite decks with larger U-ribs and PBL shear connectors

This study investigates the structural performance of the OSCCCDs with larger U-ribs and PBL shear connectors. Four OSCCCDs with larger U-ribs and PBL shear connector specimens were fabricated and tested under a static load, in which the experimental parameters were the spacing of the PBL shear connector and the spacing of the holes of the PBL shear connectors. Parametric analysis via finite element models was also carried out to explore the effects of the reinforcement ratio, the thickness of the steel plate, the thickness of the U-ribs, the thickness of the concrete slab, and the hole diameter of the PBL shear connector on the structural performance. It can be concluded from the experimental and numerical results that the OSCCCDs exhibited higher bearing capacity and better ductility. The OSCCCDs exhibited flexure failure at the mid-span and diagonal tension failure at the intermediate supports. The thickness of the U-ribs and the thickness of the concrete slab showed the highest impact on the initial stiffness and ultimate load of the OSCCCDs, followed by the spacing of the PBL shear connectors and the spacing of holes in the PBL shear connectors. The reinforcement ratio, the thickness of the steel plate, and the hole diameter of the PBL shear connector had little influence on the initial stiffness and ultimate load of the OSCCCDs. Finally, a simplified flexural analysis method can be proposed to accurately predict the elastic deflection and ultimate bending moment of the OSCCCDs under the service loads, respectively. The maximum absolute discrepancies of the elastic deflection and ultimate bending moment of the theoretical results are 8.2% and 12.0% by validating against the experimental and numerical results within the investigated ranges of parameters, respectively.

Bio-inspired design, modeling, and 3D printing of lattice-based scale model scooter decks

This research aims at enhancing the performance of scale-model scooter decks by investigating various architected cellular metamaterial and bio-inspired core structure designs, such as honeycomb, tetrachiral, re-entrant, arrowhead, and star-shaped arrangements. An initial effort is made toward the design and rapid prototyping of small-scale deck with a uniform honeycomb core structure. More specifically, polylactic acid is utilized to fabricate complex structures via fused filament fabrication technique. Investigation is then focused on its mechanical performance, such as its bending properties obtained through a three-point bending test. Simulations are also conducted with different core configurations using a geometrically non-linear finite element method which is implemented. Experiments are carried out to verify the numerical results. After validation, various patterns are modeled, and eventually, it is observed that the functionally graded arrowhead structure has the best bending resistance, compared to other bio-inspired and mechanical metamaterial structures. At a constant force of 845 N, the functionally graded arrowhead design lowers the deflection in the middle of the scale model of scooter deck by up to 14.7%, compared to the uniform arrowhead structure. Furthermore, comparing the tetrachiral and functionally graded arrowhead configurations at a constant force, a 30% reduction in central deflection was observed. Due to the lack of similar results and designs in the specialized literature, this work could potentially advance the state-of-the-art scooter core designs and provide designers with architectures that could enhance the performance and safety of scooters.

An investigation on fatigue crack propagation behavior of welded connections in UHPC reinforced OSDs using 3D crack simulation

Fatigue performance of orthotropic steel decks (OSDs) is one of the concerns that should be carefully considered, since OSD is reported as one of the most structures experiencing fatigue defects. In this study, the fatigue crack propagation behavior of welded connections in OSDs was investigated using 3D crack simulation based on the linear elastic fracture mechanics (LEFM). Fatigue testing results of rib-to-deck and rib-to-floorbeam welded specimens were considered to validate the applicability and efficiency of the crack propagation analysis. Stress intensity factors (SIFs) of the test specimens were computed using the M−integral approach, where Mode I (opening mode) and mixed-mode (i.e., combining Mode I, II, and III) of failure were considered. Additionally, the effect of the applied stress range amplitude, initial crack size, and UHPC layer thickness on the crack propagation behavior of welded joints under consideration were explored. The results indicated that the crack simulation analysis is acceptable and applicable for the evaluation of fatigue crack propagation of welded connections in OSDs. The computed SIFs demonstrated that the governing propagation mode of rib-to-deck and rib-to-floorbeam welded joints is Mode I (opening mode) and the effect of shear and tearing is limited. For both details (i.e., RD and RF welded joints) the decrease of the stress range amplitude and the increase of the UHPC layer thickness considerably slowed the crack propagation, while the increase of the initial crack size significantly accelerated the crack propagation. Comparison of the test and numerical results with the SN curves showed that FAT100 curve of the IIW specification is recommended to predict the fatigue strength of RD and RF welded joints in OSDs reinforced by UHPC layer.

Fatigue experimental study on full-scale large sectional model of orthotropic steel deck of urban rail bridge

The fatigue problem of orthotropic steel bridge decks of urban rail transit steel bridges has gradually become one of the hot research topics. And it is also a key problem that restricts the further development of rail transit steel bridges. In this paper, the orthotropic steel bridge deck structure of a long-span urban rail transit cable-stayed bridge is studied. Based on the segmental finite element model and full-scale model, the fatigue details of the joint weld between an orthotropic steel bridge deck and U-rib were studied theoretically and experimentally. The theoretical model of the segment is analyzed to obtain the hot spot stress characteristics. On this basis, the full-scale model fatigue test and the fatigue performance evaluation are completed based on the S-N curve. The results show that the fatigue performance of the bridge deck and U-rib joints of the orthotropic steel bridge deck structure model meets the design requirements and has a certain safety reserve. The joint fatigue details of the bridge deck, the U-rib joint weld, and the diaphragm plate are the sensitive areas that are most likely to occur fatigue failure first and need to be paid attention to in the later bridge maintenance and inspection.

Experimental study on flexural performance of steel-UHTCC composite bridge decks considering different shear connection degrees

Traditional steel–concrete composite bridge deck (CBD) is prone to crack in the concrete layer, which reduces its flexural capacity and durability. Due to the excellent crack resistance behavior and characteristic of tensile strain hardening, ultra-high toughness cementitious composite (UHTCC) has become a promising material to solve this problem. In this study, the flexural performance of bridge decks composed of steel and UHTCC using shear studs is analyzed by means of experimental research and finite element (FE) analysis. Five steel-UHTCC CBDs with different shear connection degrees and rib dimensions were fabricated and tested. Then, FE models of steel-UHTCC CBDs were established by ABAQUS, involving FE examples for comparing with the tests and 10 groups of models to conduct a parametric study. The flexural resistant performance of steel-UHTCC CBDs was studied concerning the key design parameters, including stud number, span length, rib dimension, thickness of UHTCC and longitudinal reinforcement ratio. The effect of shear connection degree on the flexural resistance of CBDs was discussed in detail. Finally, a modified theoretical formula was proposed for predicting the flexural resistance of steel-UHTCC CBDs.

Fatigue performance and optimal design of corrugated steel–concrete composite bridge deck

Orthotropic steel bridge deck (OSD) has been widely used in long and medium span bridges. However, traditional OSD with U-ribs is prone to fatigue cracking at the deck-to-rib welded joint. Corrugated steel–concrete composite bridge deck (CSCCBD) composed of corrugated steel plate, concrete layer and perforated plate shear connectors was proposed recently to improve the fatigue performance of the bridge deck. In this paper, comparing of the fatigue performance of OSD and CSCCBD was conducted through finite element (FE) analysis. The results showed that the stress amplitude of deck-to-rib welded joint of CSCCBD was reduced by more than 90 % compared with OSD. The fatigue problem of deck-to-rib welded joints can be solved fundamentally. It is further studied that distribution of fatigue vulnerability details of CSCCBD. The most unfavorable fatigue vulnerability details are located around the diaphragm-to-rib weld. The fatigue life of CSCCBD was evaluated based on the linear cumulative damage theory. Consequently, the effect of diaphragm cut-out on the fatigue performance of CSCCBD was studied. It was found that the diaphragm without cut-out can effectively reduce the stress amplitude caused by vehicles, and increase the earliest fatigue cracking life of details around the diaphragm-to-rib weld from 2.16 years to 43.4 years compared with OSD. Finally, the section form of CSCCBD without cut-out was optimized by response surface method (RSM). It was proved that RSM was adequate for the optimization design of CSCCBD.

Metodología para el análisis estructural de una cubierta principal de un buque FPSO soportando una grúa sobre orugas

Offshore cranes placed on the surface of Floating Production Storage and Offloading (FPSO) vessels affect the structural response of their main decks, which can alter the safe operation of the FPSO vessels. Generally, classification societies rules are used to predict the structural strength of the main deck of FPSO vessels. However, these classification societies rules are limited to estimate the variation of the structural performance of the main deck caused by the operation of offshore cranes under different hydrodynamic conditions. Here, we present a methodology to determine the alteration of the structural behavior of a main deck of FPSO vessel due to different operation conditions of a board offshore crane. This methodology considers the hydrodynamic response for two ultimate limit states: operating and storm conditions from 1000 m water depth in Gulf of Mexico with a return period of 10 and 100 years, respectively. The methodology includes finite element method (FEM) models of the main deck supporting an offshore crane to predict its structural response. The maximum von Mises stress of the main deck does not overcome its maximum permissible stress, which allows a safe operation of the FPSO crane. The proposed methodology can be used to estimate the structural behavior of main decks of FPSO vessels that are modified for supporting offshore cranes, regarding the hydrodynamic response for each FPSO under the operation and extreme conditions in its location. Thus, naval designers could select the better structural modifications of the main decks that decrease their costs of construction and maintenance.

Seismic (effect on) time history analysis for cable-stayed suspension hybrid bridge considering different geometrical configuration for far field earthquakes

To increase the maximum span of cable-stayed bridges, Uwe Starossek has developed a modified statical system. The basic idea of this new concept is the use of pairs of inclined pylon legs that spread out longitudinally from the foundation base or from the girder level. Spread-pylon cable-stayed bridge has distinct advantage like reduction of sag of cables and oscillation of cable during earthquake over traditional cable-stayed bridges. Spread-pylon also improves seismic performance of deck during strong ground motion. Here in this paper dynamic behaviour of cable stayed suspension Hybrid bridge with different structural configuration with seismic loading was studied. The primary aim , here, is to present response to Seismic effect on Cable stayed Bridges with different cable system taking under consideration SSI.It is evidently clear that Soil Foundation Structure Interaction relies greatly on various factors such as soil and its properties, manner and type of structure and/or its foundation.. In this paper , the emphasis is on the simplified model and foundation on piles. For the modelling author has used SAP2000 software. The study includes the response of the bridge modelled towards variation in the cable system under consideration of SSI. A bridge similar to that of Bridge at Ling Ding Strait China is taken as a reference and 6 models are created with variation in cable system ( ranging from original cable stayed bridge to suspension type, composite bridge and cable stayed suspension hybrid bridge). Soil modeling is done using the spring and dashpots ( Kelvin element) for simulation of SSI effects.The results observed that effects of SSI has a substantial impact on selection of system of cables and the pylon leg inclination for any Cable- Stayed- Suspension Hybrid Bridge(CSSHB)

Fatigue assessment of steel-UHPC composite deck with a thin polymer overlay in a long-span suspension bridge under static and random traffic loads

Steel-ultra-high performance concrete (UHPC) composite deck emerges as a novel structure that is promising to improve the fatigue performance of orthotropic steel deck (OSD). However, a long-span suspension bridge has a strict requirement on the self-weight of a steel-UHPC composite deck because it is susceptible to dead load variations. This study evaluates the fatigue performance of the steel-UHPC deck with a thin polymer overlay (TPO) in the Yichang Yangtze River Highway Bridge, a long-span suspension bridge, under static load and random traffic flow. The measured strains at the fatigue-prone details were employed to calculate the equivalent stress ranges and total fatigue life of the steel-UHPC deck. A three-dimensional finite element model was established and validated by experimental measurements to evaluate the steel-UHPC deck’s stiffness and the TPO layer’s crack resistance. The differences between the stress values predicted by the validated model and the experimentally measured ones were around 5%. The results showed that the steel-UHPC deck with TPO significantly reduced fatigue-prone details’ equivalent stress ranges without increasing the dead load. The maximum stress reduction at various details reached 62%, and the total fatigue life at each detail in the steel-UHPC deck reached infinite life. The TPO layer has enough crack resistance in case the deck is overloaded by 50%. Compared with the original deck, the steel-UHPC composite deck improves the OSD’s local stiffness and reduces relative deformation between structural components, thus reducing the stress ranges at fatigue-prone details and improving the bridge deck’s fatigue performance. The results can provide a reference for the design and retrofit of the deck overlay of the long-span suspension bridge with OSD.

Fatigue behavior evaluation of full-scale OSD-UHPC composite bridge deck system

To investigate the fatigue performance and fatigue damage process of the Orthotropic Steel Deck (OSD) - Ultra-High Performance Concrete (UHPC) composite bridge deck, a two-span continuous full-scale specimen was designed and tested under cyclic loading. Test results showed that the fatigue cracks firstly initiated near the lower part of the weld toe of the rib-to-cross beam welded joint, and then cracks along the weld length of the U-rib butt-welded joint developed. These observations followed by the OSD-UHPC interface debonding. The U-rib bolted joint exhibited better fatigue resistance than the U-rib butt-welded joint. The S-N curves of the rib-to-cross beam welded joint, the U-rib butt-welded joint and the U-rib bolted joint were established based on existing fatigue test data, and were compared with provisions in design codes. The S-N curves from the beam test for the short-headed stud connectors were compared with that from the push-out test. And the established S-N curves with 95% survival probability from the push-out test could be used to assess the global fatigue performance of the composite deck. Considering the durability-based critical crack width of UHPC, the established tensile S-N curve regarding critical UHPC crack width of 0.05 mm could be used to evaluate the anti-fatigue cracking ability of the UHPC layer in the composite deck system.

Experimental and Numerical Study on UHPC–RC Decks within Hogging Moment Region

Steel–concrete composite continuous bridges can take full advantage of concrete and steel, but in regions with hogging moments, cracking of the concrete deck is a big issue affecting the durability of bridges. In order to solve cracking problems within the hogging moment region, this study proposes a composite deck method using ultra-high-performance concrete (UHPC) and regular concrete (RC). In this way, the layers of UHPC and RC are composited to take advantage of the high tensile strength of UHPC materials to improve the anti-crack performance of the concrete deck within the hogging moment region. Four different specimens were designed to account for different layer thickness of UHPC. Bending experiments of the UHPC–RC composite deck were undertaken and a corresponding finite element model was established to study the behavior of the UHPC–RC composite deck. The regularity of crack development in different UHPC layer thicknesses was revealed, and the load-displacement results were compared to investigate the ultimate capacity of a steel–concrete composite bridge structure using a UHPC–RC composite deck. Finally, with consideration of material cost, a reasonable UHPC layer thickness suitable for the composite deck was obtained to provide a reference for the design of a UHPC–RC composite deck.

Built-Up Closed-Rib Steel Orthotropic Bridge Decks

A new built-up closed-rib section is proposed that may improve the installation, performance, and durability of orthotropic steel bridge decks. The rib is composed of two partial or whole standard hot-rolled steel sections which are connected by a steel plate. The concept is used to design a built-up closed-rib replacement for the Benjamin Franklin Bridge deck. In addition, section performance was compared with the actual bulb section as well as a typical trapezoidal section through finite element simulations. The analyses indicate that the built-up section has smaller stress concentration values as compared with the other sections, and hence, improved fatigue resistance is expected. Finally, it is concluded that the built-up rib has potential to be considered in future orthotropic steel deck designs.

Parametric finite element study of novel corrugated steel deck for two-way action in steel-concrete composite floors

Composite construction using steel and concrete is a widely adopted flooring construction technique. Past literature has reported ample research in the development of composite one-way slabs. However, there is a lack of understanding of two-way action in these composite slabs. It has prevented the applicability of two-way steel-concrete composite slabs in floor construction. The performance of a novel deck composed of corrugated hat sections placed orthogonally at equal spacing on a corrugated base sheet has been investigated for achieving two-way action in steel-concrete composite slab construction. Non-linear finite element (FE) models were developed and researched for feasibility in two-way action using the commercial FE package ABAQUS. The decks were analyzed in the construction stage, that is, in the absence of concrete, to isolate the properties of the new steel deck. Various parameters such as depth and spacing of hat section, angle of hat section webs and aspect ratio of the decks were investigated to establish a suitable configuration for two-way action. The effect of the parameters on the load-deflection relationship and distribution of load in two directions were studied to optimize the two-way action. Decks were also analyzed for one-way action to benchmark the change in behavior of the corresponding two-way decks. Obtained numerical results showed that the proposed corrugated deck is efficient in two-way action and could be adopted in two-way steel-concrete composite slabs. The distribution of loads in both directions improved with a decrease in hat-section spacing but increased aspect ratio and depth.

Evaluating Deck Fire Performance—Limitations of the Test Methods Currently Used in California’s Building Codes

Combustible decks are identified as vulnerable components of buildings in wildfire-prone areas. In California, combustible deck boards can comply with the requirements of Chapter 7A of the California Building Code if they pass an under-deck flame-impingement exposure test. It is desirable if standard test methods can simplify procedures while not adversely affecting the reliability of the test. The test methods should also be able to discriminate the fire performance between products on the market. In this research, the specified conditions in the under-deck flame-impingement test, SFM 12-7A-4A and ASTM E2632, were evaluated. Different deck assemblies were exposed to above-deck ember and under-deck flame-impingement exposures. During the above-deck ember exposure tests, it was observed that embers accumulated in the gaps between deck boards, on top of the support joists, and, when ignition occurred, ignited in this area. Flames spread by burning into unburned areas of the deck boards and joists, thereby providing a pathway to the building. During the under-deck flame-impingement tests, the three assumptions in the standard test method were evaluated, namely, (1) a small deck size can adequately represent the performance of larger decks, (2) the absence of wind will not noticeably influence performance, and (3) differences in joist material would not noticeably change the performance of the deck boards. Results of experiments suggested that the current Chapter 7A compliant deck boards burned intensely and exposed the cladding of the test building, resulting in an elevated temperature at the wall. It is argued that the current assumptions are an oversimplification of real-world fire performance and a change in the current California’s building code is necessary. This research demonstrated the necessity of evaluating an entire deck assembly rather than only the walking surfaces.

Probabilistic Statistics-Based Endurance Life Prediction of Bridge Structures.

With the massive construction of bridge infrastructures, bridge health monitoring systems have gradually matured in application and research, but previous research has primarily focused on structural damage detection and bridge safety warnings based on valid data. The structural details of steel bridge panels and structural systems are determined by the coupling effects of many intrinsic and extrinsic uncertainties, such as material properties, structural characteristics, manufacturing processes, and random traffic loads. The evaluation of fatigue is a difficult task. This article first builds a big data platform, utilizing its high-efficiency parallel computing capability and highly fault-tolerant distributed file system to achieve second-level monitoring data processing; ensuring real-time data cleaning, data analysis, and safety warning; and building a big data analysis and processing platform with high reliability, high availability, high storage efficiency, and high scalability of bridge health monitoring. The big data platform chooses HDFS for offline data storage and Spark for data analysis and modelling after comparing and analysing the benefits and drawbacks of various big data technologies. Kafka is used for caching real-time data, and Spark-streaming is used for reading data and real-time processing. Finally, the platform's superiority and reliability in terms of offline computing performance, real-time online performance, scalability, and fault tolerance are confirmed through experimental analysis; the optimal data cleaning method is derived by comparing and analysing monitoring data noise, jump point, and drift phenomena. This part of the research is based on bridge temperature data with stable signals and bridge strain data with fluctuating signals, taking into account the influence of different data types; the corresponding data missing repair algorithms are proposed for different types of data to form a complete and general data patching method process. The probabilistic fracture mechanics theory, in comparison to the traditional deterministic fatigue assessment method, can better reflect the essential uncertainty of fatigue problems and is an effective way to assess the fatigue performance of orthotropic steel bridge decks. The goal of data patching is to ensure data recovery accuracy of over 90%, with no patching repair required for monitoring data with too much missing data. The endurance life of bridge structures is predicted using a big data probabilistic statistics approach based on a variety of factors such as material properties, construction characteristics, manufacturing processes, and random traffic loads.

Structural performance evaluation of UHPC/conventional concrete cast on new Y-shape FRP stay-in-place formwork for concrete bridge decks

Overthe pastfewyears, there has been a rise in the use of Stay-In-Place (SIP) structural formworks made of fibre reinforced polymer (FRP). This study investigates the performance of decks made of FRP SIP structural formworks with an improved configuration using conventional and ultra-high performance concrete under static loadings. The proposed new composite deck consisted of a glass fibre reinforced polymer plate stiffened with Y-shape ribs for resisting tensile and shear stresses while reinforcements was placed on the compressive side of the deck. The new composite deck was compared with conventional reinforced concrete solid decks and a composite deck consisting of square hollow section (SHS) stiffeners. Results showed that the deck made of Y-shape stiffeners failed in punching shear, and the use of Y-shape stiffeners significantly enhanced the ultimate strength and shear capacity of the proposed deck. It was also concluded that the voids in the concrete deck with SHS stiffeners resulted in lightweight structures but had a negative influence on the ultimate strength of the deck cast on FRP SIP formwork. Increasing the concrete strength from 34 MPa to 140 MPa resulted in a 71% enhancement in the maximum load-carrying capacity but did not considerably influence their stiffness.

Static and fatigue performance of steel bridge decks strengthened with air-cured UHPC

Adding a thin layer of ultra-high performance concrete (UHPC) onto the steel deck plate is an effective approach to improve the fatigue performance of orthotropic steel decks (OSDs) through increasing structural stiffness and load-carrying capacity, but a wide industrial acceptance of the approach is hindered by heat curing of UHPC. In this study, air-cured UHPC with low shrinkage was adopted to fabricate the cast-in-situ topping layer for the composite decks. Experiments were carried out to investigate the structural behavior of the composite decks under static and fatigue loading. Experimental results showed that (1) UHPC with relatively high strengths and low shrinkage could be manufactured without any special curing regime; and (2) the composite decks had enough mechanical strengths and fatigue resistance to withstand service loads. Finite element analyses were performed to determine the contribution of air-cured UHPC on the fatigue performance of OSDs. Finally, a hot spot stress reduction factor was introduced to assess the long-term effectiveness of air-cured UHPC in improving the fatigue performance of OSDs. Results suggested that UHPC cracking and the associated degradation in structural stiffness had limited effects on the fatigue behaviors of composite decks.