Concrete Deck Research Articles

Shrinkage effect and mechanical performance of steel-ultra-high performance concrete composite deck under negative bending action

Shrinkage effect can result in damages in steel-UHPC composite decks. And these damages may even cause mechanical performance degradations. The details are critical to deck design practice and evaluation theory establishment while not being clearly understood. In this study, static shrinkage monitoring and negative bending tests on two full-scale segmental composite deck specimens (D12 and D16) were sequentially conducted. 12-mm- and 16-mm-diameter reinforcements were respectively embedded in the specimens. Simulation and parametric analysis were executed as well for further understanding. The 90 days static shrinkage monitoring results showed the maximum induced compressive strains on reinforcements of D12 and D16 were 559 με and 328 με. The maximum compressive strains on steel deck plates were 80 με and 82 με. It indicated shrinkage effect cannot be ignored. The bending test results showed the UHPC tensile strain maximums were 1458 με and 1149 με in the two specimens when the maximum UHPC crack width was 0.10 mm. Moreover, the simulation analysis results also showed that the model with 90 days shrinkage effect had a 16% lower bending secant stiffness at the load level equivalent to allowable UHPC crack width. And the reduction increased to nearly 40% when the crack width reached 0.10 mm. In addition, the parametric analysis showed that a strain-hardening feature could be favorable to delay the UHPC damage evolution compared with a strain-softening one with relatively lower tensile strength. These results provided important support to the design practice of steel-UHPC composite decks.

Analysis and Full-Scale Testing of New MASH TL-4 Bridge Rail for William P. Lane, JR. Bridge, Annapolis, MD

The purpose of this project was to analyze and test a new combination concrete and metal bridge rail for the William P. Lane (WPL) Bridge over the Chesapeake Bay east of Annapolis, Maryland, U.S., to Manual for Assessing Safety Hardware (MASH) Test Level 4 (TL-4) specifications. The new combination bridge rail is 50 in. in height and anchors to an 8 in. thick segmental precast concrete deck. The bridge rail was anchored to the deck using widely spaced 1 in. diameter bent anchor bolts that were cast into the concrete parapet sections. The length of the parapet and deck sections were approximately 150 ft. The deck sections were constructed with tongue and groove joint connections. The single tube metal rail, which bolted to the top of the concrete parapet sections, was anchored to the concrete using conventional cast in place anchor bolts. The transverse reinforcement in the deck, in the immediate area of the MASH TL-4 impact, was instrumented with strain gages to measure the strain and force in the transverse deck reinforcement. In addition, load cells were applied to the 1 in. diameter anchor bolts in the parapet to measure the anchor forces from the MASH TL-4 impact. This paper summarizes the results from the bridge rail analyses, measured forces in the transverse deck reinforcement and anchor bolts from the crash loads, and the results from the full-scale testing program. The new combination bridge rail performed very well with respect to the MASH TL-4 specifications. Details of the design and testing of the combination bridge rail are provided in this paper.

Analysis of the Deflection of Over-Truss Bridge Deck Using Finite Element Approach

Deflection is basically the bend or curve that occurs within materials when loads are applied to them. A structure should be designed to be able to properly resist the applied loads and failure to do that makes the deflection visible and consequently lead to failure. During the course of this work the dead load, live load and environmental wind load acting on the bridge structure were calculated using the Analytical method and the calculated loads were used to analyze the bridge numerically using the STAAD pro software. The Plate stress animation from the STAAD software showed portions that were under intense loading on the concrete deck. From the animation, Steel beams 42, 45, 49, 53 and 57 were directly supporting these portions of the decks and were chosen for analysis. These beams were analyzed in terms of deflection, shear and bending. The values for shear, deflection, and bending for the five steel beams were compared under both approaches and their percentage difference was calculated. Comparing the results obtained from the analytical and numerical method gave a percentage difference of 4.39 %, 0.6 %, 0.93 %, 3.67 % and 1.19 % for shear, 6.29 %, 3.23 %, 1.07 %, 4.28 % and 1.14 % for bending, 12.5 %, 7.6 %, 4.08 %, 2.45 % and 2.6 % for deflection. 80 % of results obtained were less than 5 % in percentage difference and with this result, it is concluded that both methods are suitable for design. The Numerical method was nevertheless chosen to be a more economical and accurate method because it incorporates reliable safety factors that cater for uncertainties in its approach

Nonlinear Thermo-Structural Analysis of Lightweight Concrete and Steel Decking Composite Slabs under Fire Conditions: Numerical and Experimental Comparison

Composite slabs with steel decking profiles are widely used in building construction. However, the literature on the fire resistance of lightweight concrete (LWC) composite slabs with steel decking is limited. In this work, the thermo-structural performance of LWC composite slabs with trapezoidal steel decking was studied under fire conditions. A total of 12 experimental fire tests were carried out using specimens of 160 mm thickness, 1120 mm width and 2030 mm length, in which nine composite slabs were made of LWC and the remaining three slabs were made of normal concrete (NC) to serve as a benchmark for comparison. All the samples were tested in a furnace following EN 13381-5, applying the standardized time–temperature curve and constant load. During the experimental tests, phenomena such as the vaporization of the free water inside LWC, debonding between steel decking and concrete and changes in material properties affected the thermo-structural performance of composite slabs. The test results show that the load-bearing capacity of lighter slabs does not assure the minimum structural behavior of R30. However, the lighter the concrete is, the lower the thermal transmittance, improving the slabs’ thermal performance under fire conditions. Advanced nonlinear numerical models were developed to predict the thermal and structural performance of the studied LWC composite slabs in terms of temperature and time-displacement. The influences of key factors such as vaporization, thermal strains and debonding were included using material properties and a thermal contact conductance interlayer. Finally, the nonlinear models and the experimental results were compared. The difference between the experimental and numerical values was less than 15%, showing that the numerical results were in good agreement with the experimental results. The results of this study also compared the performance of LWC composite slabs with the NC composite slabs, giving rise to interesting conclusions from a practical point of view.

Experimental and numerical studies on flexural behavior of fiber continuous joints of precast UHPC decks

AbstractThis study investigated the flexural behavior of ultra‐high‐performance concrete decks with an innovative joint of fiber continuity at the joint interface. An experimental program with 21 specimens was designed and tested. Four types of joints were studied, that is, lap‐spliced rebar, fiber continuity, combination of fiber continuity and lap‐spliced rebar, and combination of additional reinforcement and lap‐spliced rebar. Finite element models were built and benchmarked using the test results. The influence of reinforcement ratio and interfacial fiber content was investigated. Experimental and numerical results showed that a joint with a combination of fiber continuity and lap‐spliced rebar achieved similar flexural performance as cast‐in‐place decks. In addition, the design theory of the Swiss code (SIA 2052‐2016) was recommended with promising accuracy in estimating the flexural capacity of precast ultra‐high‐performance concrete decks, based on the tensile strength of joint interface with various fiber contents.

Structural performance of steel–concrete composite beams with UHPC overlays under hogging moment

This paper investigates the usage of a thin layer of Ultra-high performance concrete (UHPC) reinforcing the concrete decks at the hogging moment region of steel–concrete composite beam bridges. An integrated experimental and numerical study was conducted to assess the influence of several parameters, such as the type of overlay concrete, arrangement of interfacial shear steel rebars, and presence of wire meshes, on the structural performance of the retrofitted composite beams. In the experimental program, five steel–concrete composite beams, including one normal concrete (NC)-strengthened composite beam and four UHPC-strengthened composite beams, were fabricated and tested. Experimental results indicate that the application of UHPC overlays significantly improved the structural performance of the retrofitted composite beams, and providing wire meshes in UHPC overlays restricted crack propagation of combined UHPC-NC decks. The bending stiffness and cracking resistance of the UHPC-strengthened composite beams were 25.2% and 368.7%, respectively higher than those of the NC-strengthened composite beams. As expected, the shear steel rebars can avoid sliding and uplifting at the substrate-to-overlay interface, and the utilization of shear steel rebars by a ratio of 0.28% magnified the bending stiffness and cracking resistance of the retrofitted beams by 9.7% and 5.1%, respectively, as compared to those without the rebars. In the numerical simulation, a three-dimensional finite element (FE) analysis of the composite beams was carried out, and the simulation results were validated with the experimental data. It is shown that the retrofitted beams under hogging moment finally failed due to fracture of the longitudinal steel reinforcements in the original decks, regardless of the presence of bonded overlays. Moreover, an analytical model for the combined UHPC-NC deck was developed to provide reliable predictions for the composite beams with UHPC overlays under hogging moment.

Experiment Study on Residual Flexural Capacity of Prestressed Concrete Deck Slab Under Fatigue Loading

The deterioration of a concrete deck damaged by repeated traffic loads could directly affect its performance. Two full-scale specimens modified from a precast, prestressed concrete (PC) deck slab on a 12.65-m-wide composite bridge with twin I-girders spaced at 7.05 m were tested to study the degradation of mechanical performance of the slabs under fatigue loading. The depth of the slabs was 30 cm at the midspan and 40 cm at the two supports. One specimen was 3.0 m wide and conducted a three-stage fatigue loading before the static destructive loading, the other was 1.5 m wide and performed a static load test to failure only. The ultimate strength of specimens was obtained, and the variation of deflection, reinforcing strain, and cracks were discussed. The test results showed that the failure mode of the PC slabs was flexure subjected to static load. Fatigue loading significantly degenerated the stiffness of the slab, and the maximum stiffness reduction was about 35.2 %. The distribution scale of cracks was expanded about twice as much at the same load level under the fatigue loading. It could be deduced that the fatigue loading could enlarge the crack width, by comparing the measured results of concrete crack widths of the two specimens, however, the design provisions did not take this into account. A comparison between the transformed flexural capacity of the two specimens showed the residual flexural capacity was reduced by 7.8 %. Moreover, an analysis model was developed to predict the residual flexural capacity of PC slabs.

Fusion of NDE Scanning and Photogrammetric Data for Concrete Bridge Decks and Girders Condition Assessment

The first case history would present 3-D results of Impact Echo Scanning and Ground Penetrating Radar (GPR) Scanning plus Spectral Analyses of Surface Waves tests of post-tensioned concrete bridge girders. The NDE results were overlaid on photogrammetric images of visible corrosion/cracking damage to the concrete bridge girders of an aging bridge due to de-icing salts and a marine environment. Cart-based scanning with GPR and Impact Echo and Spectral Analyses of Surface Waves NDE methods is commonly being conducted of both bare concrete decks and asphalt overlaid decks to map both top and bottom delaminations and depth of concrete cover. The data is being used in conjunction with chlorides and carbonation testing of concrete cores to recommend repairs and evaluate remaining service lives for bridges. Photogrammetric images of bare concrete in particular are being used to visibly compare areas of spalling, delamination and deck patching for improved interpretation, visualization and mapping of internal deck delaminations and other concrete damage with this data fusion approach to provide more accurate surface and full-depth images of bridge deck conditions.

Full-scale experimental study on continuous UHPC slabs of steel-UHPC composite deck system

The heavy self-weight and the cracking of normal strength concrete (NSC) deck slabs hindered the application of steel-concrete composite girders in long-span bridges. These problems can be solved by using ultra-high performance concrete (UHPC) deck slabs instead of the NSC deck slabs. Based on Yellow River Bridge of Zhanhua-Linzi Highway, a steel-UHPC composite cable-stayed bridge with span length of 442 m, full-scale tests on seven continuous UHPC (NSC) deck slabs were conducted. The studied parameters were sagging-to-hogging reinforcement ratio, concrete type, yield strength of steel bars and wet joints. The static properties of continuous UHPC (NSC) deck slabs were investigated in detail, including failure modes, load-deflection response, cracking behavior, strain development and moment redistribution. Discussions were made on the effect of different parameters according to the experimental data. Results showed that the use of UHPC can avoid shear failure, which was the case for the continuous NSC slab. Reducing the sagging-to-hogging reinforcement ratio from 1.00 to 0.63, the failure mode changed due to the altered formation order of plastic hinges. The ultimate capacity was decreased while the ductility and moment redistribution were improved by decreasing the yield strength of steel bars. The existence of wet joints significantly weakened the deck slabs. Strengthening the wet joints with steel plates can effectively compensate for this effect and even achieve better mechanical properties compared with integrally cast slabs. Furthermore, placing a comb-shaped wet joint at the intermediate support of continuous slab will result in a certain decrease of ultimate capacity and stiffness, which is acceptable for the transverse direction with relatively small internal forces. It is suggested that wet joints should be avoided at the supports of continuous deck slabs along the longitudinal direction.

The construction of the Cross Bay Link bridge in Hong Kong

The Cross Bay link (CBL) bridge is a 1 km sea crossing that forms the centrepiece of the new east–west express highway link in Hong Kong. This £250 million project features an iconic 200 m span butterfly double-arch bridge and a series of concrete box girder spans supported on specially sculpted V-piers and large piled foundations. This paper describes the innovative construction methods adopted for building the bridge safely and efficiently in an extremely challenging marine environment, a process that relied on the extensive use of design for manufacture and assembly solutions, with most of the bridge elements above the sea level being prefabricated or precast off site. This includes the construction of the 10 000 t steel arch bridge, which was fully prefabricated near Shanghai, then transported to Hong Kong by a semi-submersible barge, and eventually erected onto the piers using the float-over method. In addition, most of the concrete decks, piers and the pile cap shells were precast off site and then lifted into position on site. This project holds a number of engineering records in Hong Kong, including the longest arch bridge, the first-time adoption of S690QL high-strength steel for major bridge elements and the largest scale implementation of the float-over erection method.

Castellated Beams with Fiber-Reinforced Lightweight Concrete Deck Slab as a Modified Choice for Composite Steel-Concrete Beams Affected by Harmonic Load

The behavior investigation of castellated beams with fiber-reinforced lightweight concrete deck slab as a modified choice for composite steel-concrete beams affected by harmonic load is presented in this study. The experimental program involved six fixed-supported castellated beams of 2140mm size. Three types of concrete were included: Normal Weight Concrete (NWC), Lightweight Aggregate Concrete (LWAC), and Lightweight Fiber-Reinforced Aggregate Concrete (LWACF). The specimens were divided into two groups: the first comprised three specimens tested under harmonic load effect of 30Hz operation frequency for 3 days, then the residual strength was determined through static load application. The second group included three specimens identical to those of group I, tested under static load only. The results show that LWAC was more influential than LWACF under harmonic load. The reduction in the residual strength of LWACF and NWC deck corresponding to the harmonic load was 0.94 and 0.7% respectively. The outcome proved that using LWACF as a deck for the castellated steel beams affected by harmonic load presents a significant choice with weight reduction of 16% compared to NWC. Steel fiber’s tensile strength 1700MPa enhanced the absorbed energy and the ductility factor by 0.4 and 0.5% respectively.

Laboratory study of a hydronic concrete deck heated externally in a controlled sub-freezing environment

Geothermal heating of bridge decks is a reliable and sustainable method for bridge de-icing that has been increasing in demand since conventional de-icing methods were proved to be environmentally hazardous. Previous research on geothermal heating of bridge decks relied on hydronic pipes embedded inside of bridge decks, which are confined to newly constructed bridges. For existing bridges, a newly devised method for external heating has been recently tested under limited laboratory conditions to determine its overall performance. This study explores laboratory heating tests of a concrete slab with a thickness representing a typical concrete bridge deck. This slab was equipped with a simulated geothermal bridge de-icing system and tested inside a freezer subjected to sub-freezing controlled conditions. Various winter scenarios were applied to the system to determine its heating performance and how feasible it will be for the system to be transferred to the field. A prediction equation was developed to estimate the total energy reserves required to permit de-icing, and statistical analysis was performed and validated with test results. The slab surface heat flux was estimated to range from 27 W/m2K to 73 W/m2K from the heating test. The externally-heated deck can be designed with the developed prediction equation for snow melting.

CO2-Optimization of Post-Tensioned Concrete Slab-Bridge Decks Using Surrogate Modeling.

This paper deals with optimizing embedded carbon dioxide (CO2) emissions using surrogate modeling, whether it is the deck of a post-tensioned cast-in-place concrete slab bridge or any other design structure. The main contribution of this proposal is that it allows optimizing structures methodically and sequentially. The approach presents two sequential phases of optimization, the first one of diversification and the second one of intensification of the search for optimums. Finally, with the amount of CO2 emissions and the differentiating characteristics of each design, a heuristic optimization based on a Kriging metamodel is performed. An optimized solution with lower emissions than the analyzed sample is obtained. If CO2 emissions were to be reduced, design recommendations would be to use slendernesses as high as possible, in the range of 1/30, which implies a more significant amount of passive reinforcement. This increase in passive reinforcement is compensated by reducing the measurement of concrete and active reinforcement. Another important conclusion is that reducing emissions is related to cost savings. Furthermore, it has been corroborated that for a cost increase of less than 1%, decreases in emissions emitted into the atmosphere of more than 2% can be achieved.

Performance of semi lightweight concrete composite deck slabs under falling mass

In the present scenario probability of unexpected and accidental loading is high for the infrastructures. There is an urgent need to analyse these structures to check their viability against impact load. Composite structures are currently used to utilize the benefits of different materials. Past research works focused on the response of composite slabs under static load. Studies related to the impact response of composite slabs are limited, and the behaviour of less dense slabs is still to be explored. There is a demand to focus on the reaction of semi-lightweight aggregate concrete for composite grooved trapezoidal decking slabs subjected to drop mass impact. The study focused on the cushioning effect of six composite slab specimens (1000 mm × 930 mm × 80 mm) along with welded wire mesh and steel fibers as secondary reinforcements. Two were cast using control concrete (NC), and four were cast using lightweight concrete (LC). The collision was achieved by dropping a 55 kg steel cylinder to hit the center of the slab from a height of 1 m. Numerical modeling and analysis of similar slabs under impact load were carried out in ANSYS. The parameters concentrated are impacted force–time history, acceleration, crack pattern, bond-slip behaviour, and stress contours. The results show that lightweight concrete with welded wire mesh as secondary reinforcement could be effectively utilised as a cushioning layer for the composite deck system under falling mass scenarios.

Modelling the Thermal Effects on Structural Components of Composite Slabs under Fire Conditions

This paper presents a finite-element-based computational model to evaluate the thermal behaviour of composite slabs with a steel deck submitted to standard fire exposure. This computational model is used to estimate the temperatures in the slab components that contribute to the fire resistance according to the load-bearing criterion defined in the standards. The numerical results are validated with experimental results, and a parametric study of the effect of the thickness of the concrete on the temperatures of the slab components is presented. Composite slabs with normal or lightweight concrete and different steel deck geometries (trapezoidal and re-entrant) were considered in the simulations. In addition, the numerical temperatures are compared with those obtained using the simplified method provided by the standards. The results of the simulations show that the temperatures predicted by the simplified method led, in most cases, to an unsafe design of the composite slab. Based on the numerical results, a new analytical method, alternative to the simplified method, is defined in order to accurately determine the temperatures at the slab components and, thus, the bending resistance of the composite slabs under fire conditions.

Karakteristike posmične veze u spregnutoj ploči od čelika i betona

Steel-concrete composite slabs with cold-formed, profiled steel deck sheets are popularly used in steel-framed buildings. In these slabs, the deck platform acts as a working platform during construction and also as tensile reinforcement under in-service load conditions. The shear bond capacity of the composite slab is evaluated in this study for two different profile steel deck sheets. Specifically, their composite behaviour is investigated by casting and testing twelve full-scale composite deck slab specimens using the two-point loading system. In addition, based on the shear span length and profile height, the structural performance of the composite deck slab is analysed in terms of load-displacement response, shear bond capacity, ductility index, and load-slip behaviour. The results show that the most common failure of all tested specimens occurs due to the longitudinal shear failure between the concrete and profile deck sheets. As the longitudinal shear is a complex phenomenon, empirical approaches are used to evaluate the shear bond mechanism between the concrete and profile deck. The verification and comparison of experimental test results are performed with conventional and simplified m-k models based on the profile deck depth. The validated results reveal an acceptable level of reliability for prediction of each profile height based on the m and k interaction values.

Statistical Data Analysis of the Aging Effect on Time-Dependent Corrosion Rate for Steel Girder Bridges with Concrete Decks

Statistical Data Analysis of the Aging Effect on Time-Dependent Corrosion Rate for Steel Girder Bridges with Concrete Decks

Design features and best practice in podium deck waterproofing : Examples and perspectives from UK industry

Podium decks — a basement roof at, or around, ground level which is not covered by superstructure — are an increasingly common feature in the modern built environment. This increase may be partly attributed to growing awareness of the need for sustainability. Green roofs, sustainable urban drainage, water attenuation and even parks and farms are being located on top of podium decks. Waterproofing of these podium decks is vital in order to use the space created beneath and also to prolong the life expectancy of the structure. This research analyses the available best practice guidance and then compares the key waterproofing design features with opinions from industry. Opinions are gathered first through 78 questionnaire respondents and then interviews with four experienced respondents with unusual views. These findings are then compared with case studies of podium decks with waterproofing failures. This research suggests that robust podium deck waterproofing design comes from the following choices in the fundamental features of waterproofing design for podium decks: a) reinforced concrete structural deck; b) fully bonded waterproofing membrane; c) waterproofing laid to a gradient to falls; and d) provision of a drainage void over the waterproofing layer. As a result of these findings, this paper calls for more authoritative best practice guidance on podium deck waterproofing design in a bid to reduce pressures in procurement that lead to weaker waterproofing design choices. This research may be of interest to built environment professionals because it identifies some fundamental features of podium deck waterproofing design and clarifies which design choices are perceived to deliver more robust waterproofing than others.

Experimental Study on Flexural Performance of HSS-UHPC Composite Beams with Perfobond Strip Connectors

In order to explore the flexural performance of high-strength steel (HSS)/ultrahigh performance concrete (UHPC) composite beams, a total of six HSS-UHPC composite beams with varying levels of interfacial shear connectivity, arrangements of perfobond strip connectors (PBL), and variable thicknesses of concrete decks were fabricated and tested. The failure mode, flexural stiffness, load-deflection curve, strain history, and interfacial slippages obtained from the composite beams are presented and discussed. Experimental results indicated that despite the lightweight feature of such a hybrid system, the HSS-UHPC composite beams exhibited high flexural stiffness and favorable ductility. As the level of shear connectivity decreases, the bending resistance of HSS-UHPC composite beams decreases, while the beams’ ductility exhibits slight enhancement. The PBL arrangement has crucial effects on the behavior of HSS-UHPC composite beams, and the beams’ ductility was improved by approximately 48.9% by alternating uniformly distributed PBLs to a nonuniform distribution pattern. Experimental results also highlighted the influence of the UHPC deck thickness on the flexural performance of the composite beams. As compared to an 80.0 mm-thick UHPC deck, the 100.0 mm-thick UHPC deck witnessed increases in bending stiffness, yield moment, and ultimate resistance of the composite beam by 19.8%, 22.8%, and 14.6%, respectively. Comparisons between the results obtained from the tests and analytical procedures for predicting HSS-UHPC composite beams resistances were performed to assess the feasibility of existing design approaches. Results of the study confirmed that equations recommended by GB 50017-2017 have favorable accuracy in calculating the bending resistance of HSS-UHPC composite beams with uniformly distributed PBLs, while for HSS-UHPC composite beams with nonuniformly distributed PBLs, both the AASHTO LRFD and Ban et al. equations are recommended.

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.