Ribbed Deck Research Articles

Two new bridges over the River Vardar in Skopje

This paper presents some aspects of the design of two new bridges over the River Vardar in Skopje. "Mihajlo Apostolski" is an integral bridge, consisting of two separate structures (22.05 + 50.50 + 21.05 m = 93.6 m length and 15.3 m width). The bridge deck is made up of a two-cell prestressed cast-in-situ box girder with a parabolically variable cross section. The abutments and the piers are wall-shaped and supported on single and double row piles, respectively. The side spans, together with the approaching structures, were proposed to be built on traditional scaffolding, while the middle span over the minor riverbed was built with a free cantilever method. The extradosed bridge at Ljubljanska Street is 27.5 + 56 + 27.5 m = 111 m long and 24.1m wide. The ribbed deck (two post-tensioned main girders, cross girders, and deck slab) is supported from above by 32 parallel stay cables. The 12.6 m high pylons are located at the intermediate supports. In the base, the four piers have a rectangular cross section that has been rotated 45 degrees. The superstructure is supported by pot bearings. A deep foundation on piles was chosen. Cast-in-place construction of the superstructure was foreseen. The design of the bridges was done according to Eurocodes and respecting the fib and PTI recommendations. Detailed numerical analysis was carried out in the FEM software SOFiSTiK and additional auxiliary software.

Parametric equations for notch stress concentration factors of rib—deck welds under bending loading

Parametric equations for notch stress concentration factors of rib—deck welds under bending loading

Additional and total deflection of composite symmetric cellular beams

Building floor systems are made from steel girders connected to a concrete slab or a composite slab with ribbed decking. In office buildings with large free span areas, different technical and economic constraints lead to a substantial reduction of the floors thickness, by providing openings in the webs of beams designed to allow the passage of pipes and ducts.The web openings may have a significant effect on the deflection of beams subjected to transverse loading and in many cases, be the paramount parameter in their design.In this paper, an analytical model previously developed for the evaluation of total deflection of composite symmetric cellular beams has been improved, through a better consideration of the flexural stiffness of the beam webs under vertical shear forces. The analytical results presented are compared against other existing proposals in the literature then verified against the numerical solutions obtained using the Cast3m software.

Fatigue Performance of a Lightweight Composite Bridge Deck with Open Ribs

An innovative lightweight composite deck (LWCD) is proposed for steel bridges to avoid premature fatigue cracking. The composite deck is composed of an open-ribbed orthotropic steel deck (OSD) and a thin ultrahigh-performance concrete (UHPC) layer. This study is based on a suspension steel bridge in China, namely, the Second Dongting Lake Bridge. The following investigations were performed: (1) preliminary finite-element analysis (FEA) was carried out to evaluate the vehicle-induced stress ranges (i.e., Δσ = σmax − σmin) of six typical fatigue-prone details; (2) parameter analyses were performed to investigate the effects of the shape of cutouts and the thickness of the floor beams; and (3) two fatigue tests, one that used a full-scale LWCD panel and another that used a LWCD beam specimen, were conducted to reveal fatigue performance of the OSD and the stud shear connectors, respectively. Results of the preliminary FEA show that, with the contribution of the UHPC layer, the vehicle-induced stress ranges at some fatigue details of the LWCD, such as the rib–deck plate welded joints and the splice welds of the longitudinal ribs, were reduced to be less than their constant-amplitude fatigue limits, which indicates theoretically infinite fatigue lives of these details. The parameter analyses reveal that the apple-shaped cutout had relative good fatigue properties among the four cutout schemes and that the thickness of the floor beams is recommended to be 14–18 mm. According to the fatigue tests on the composite panel specimen and on the composite beam specimen, both the open-ribbed OSD and the stud shear connectors exhibited satisfactory fatigue endurances, which were much greater than 2 million cycles. The current theoretical and experimental investigations reveal that the proposed open-ribbed LWCD has favorable fatigue performances.

Effect of machined profile, zinc oxide and titanium dioxide particles on checking southern pine deck boards during weathering

The aim of this research was to test the hypothesis that the combination of profiling, treatment and a surface coating with nanoparticles will be effective at reducing checking in deck boards exposed to the weather. In this study southern pine (Pinus sp.) deck boards were machined to flat (control) and ribbed surface profiles. The specimens were treated with aqueous copper amine azole (CA-C) using a vacuum/pressure method and coated with nano-ZnO and micronised TiO2. Boards were exposed to accelerated weathering for 576 h. The number, length and width of checks that developed in the boards were quantified and the average amounts of cupping, twist and bowing occurring in the weathered wood were examined. The results of the statistical analysis showed that all of the coated ribbed decking samples had lower average check numbers, lengths and widths compared to the end-matched flat untreated specimens. Checks were also shorter and narrower in the profiled southern pine deck board than in the unprofiled specimens. Furthermore, the lowest amount of cupping, twist and bowing were observed for specimens profiled and coated with the TiO2. Therefore, the authors conclude that the coated ribbed decks looked significantly better than the flat decking.

Effect of profiling and preservative treatments on the weathering characteristics of Southern pine deck boards

In this study, Southern pine (Pinus sp.) deck boards were machined to flat (control) and ribbed surface profiles. The specimens were treated with aqueous formulations of 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one (EL2) and amine copper azole (CA-C) using a vacuum/pressure method. Boards were exposed to accelerated weathering for 576 h (24 days). The results showed all of the preservative-treated ribbed decking samples had a lower average number of checks compared to end matched flat samples. Checks were also shorter and narrower in the profiled deck boards than in the unprofiled specimens. Furthermore, the lowest amount of checking, cupping, twist and bowing was observed for specimens profiled and treated with the EL2.

The Total Deflection of Composite Cellular Beams Under Transverse Loading

Increasingly, floors are made today from a steel girder connected to a concrete slab or a composite slab with ribbed decking. Mixed operation indeed makes it possible to optimize the structural exploitation of these two materials. In many applications, especially in office buildings with large free span areas, different technical and economic constraints lead to a substantial reduction of the floors thickness, by providing openings in the webs of beams designed for the passage of pipes and ducts. Serviceability checks including flexural deflections under transverse loading are of high importance in the design, especially in floor systems and pedestrian bridges where live loads are present. In this paper, an analytical model for calculating deflections due to concentrated or uniformly applied transverse loads have been developed. The additional deflection due to the effects of vertical shearing at the opening is included in the analysis. The analytical results presented are verified against existing proposals and numerical solutions obtained using the Cast3m software.

Hot spot stress analysis on rib–deck welded joint in orthotropic steel decks

Orthotropic steel decks are used in beams and cable-supported bridges. Fatigue cracks of the vertical rib–deck welded joint have been found in some of the bridges. In this paper, the structural hot spot stress (SHSS) approach is applied to evaluate the rib–deck fatigue. Refined solid models are built using a multi-sub-model technique. Stress around the weld tip is analyzed and effects of the weld profile, the weld toe radius and mesh size are discussed. The SHSS is analyzed using the surface stress extrapolation method, the stress linearization method and the 1mm stress method. Fatigue strength of the joint based on the SHSS is proposed. Results of this study show that the refined multi-sub-model considering the weld detail can reflect the mechanical behavior of the rib–deck joint. Variation of the SHSS by the three methods decreases to less than 10% and a convergent SHSS is achieved using the refined models. The derived fatigue strength for the rib–deck joint using the SHSS of the refined models is close to FAT100. A more precise fatigue strength prediction can be achieved using the refined model while the coarse models result in a conservative design.

Behaviour of Steel-Concrete Composite Beam with High Ribbed Deck

Steel-concrete composite structures are structures that combine the advantages of both used materials. An advantage of such structures is their high bending resistance, which has a positive effect on the overall weight of the structure. The disadvantage could otherwise be a slightly complicated design of individual elements.The paper describes an experiment with two simply supported 6 m long steel-concrete composite beams loaded in their thirds. The each beam is made of standard steel rolled profile and concrete slab concreted into the transversally oriented trapezoidal metal sheet with rib height equal to 135mm, although European standard restricts the rib height only to 80mm for common use. The research is focused mainly on deflection of beam, whether partial or full shear connected and also deals with the possibility of modelling these structures using the finite elements method. The shear resistance of stud in narrow and wide concrete rib is investigated too.

Rolling Fatigue Test of Large-Sized UHPC Member for Cable Stayed Bridge

Recently, research strives to apply Ultra High Performance Concrete (UHPC) to large-sized structures owing to its remarkable mechanical performance and durability compared to normal concrete. The Korea Institute of Construction Technology proposed SuperBridge800, an edge girder type UHPC cable stayed bridge with central span of 800 m, through its detailed design. The bridge is designed to be erected through the connection of precast UHPC segments. The precast UHPC segment is monolithically composed of one ribbed deck slab and edge girders at each side. The connection between the precast segments is achieved by steel bars at the edge girders and by UHPC cast-in-place wet joint at the slab. Despite of the outstanding mechanical performance of UHPC, the fabrication of large-sized members is a difficult task since UHPC hardens faster than normal concrete and requires a special curing process. Therefore, the constructability of large-sized UHPC segment should be secured to achieve SuperBridge800. Besides, the performance of the connection between segments should also be guaranteed, especially in terms of the fatigue performance of the UHPC cast-in-place joint, which constitutes a weak point. To that goal, two half-scaled UHPC segments are manufactured and the constructability is examined by fabricating a large-sized UHPC member connected with respect to the design conditions. This study conducts rolling fatigue test on the so-fabricated large-sized UHPC member. Rolling fatigue test is carried out up to 2 million cycles considering actual vehicle load at each center and quarter points of the member. The test results confirm that the service limit state is satisfied.

Behaviour and strength of composite slabs with ribbed decking

Behaviour and strength of composite slabs with ribbed decking

Composite Slab Behavior and Strength Analysis. Part I: Calculation Procedure

A new calculation procedure is described that provides an alternative to full-scale testing for composite slabs with ribbed decking used in buildings. The procedure consists of combining shear-bond test results with a numerical analysis to predict the behavior and strength of composite slabs. It may be used to analyze either single spans or multiple spans. The procedure incorporates certain simplifications and assumptions that allow for reasonable yet conservative prediction of both behavior and strength. In particular, chemical bonding between the concrete slab and decking and concrete tension behavior are ignored because they are brittle in nature. Advantages of using this procedure rather than full-scale test results are versatility and reduced cost, the estimation of deformations at working loads, the inclusion of additional variables such as end anchorage (over the end supports), additional positive moment reinforcement (in the span), and reinforcement in negative moment regions (near interior supports). This calculation procedure may also be used for the development of new decking and to improve the performance of slabs with existing decking. Examples of calculations are presented for single-span composite slabs.

Composite Slab Behavior and Strength Analysis. Part II: Comparisons with Test Results and Parametric Analysis

The results of selected tests on full‐scale one‐way single and continuous span composite slabs with ribbed decking are presented. Variables investigated in these tests include the number of spans, the presence of embossments in the decking, end anchorage (both welded and shot‐fired shear connectors), and negative moment reinforcement near interior supports. An example comparison is given between a standard test and the calculation procedure combining shear‐bond test results with a finite element analysis (the calculation procedure was presented in part I). The importance of composite slab internal moment resistances as a function of the applied load is examined. For a composite slab, three internal moment resistance elements are of importance: the decking, concrete slab (including additional reinforcement), and the interaction between decking and concrete slab. Parametric analyses based upon the calculation procedure predictions are performed for three decking geometries using limiting slenderness ratios. Decking types were chosen to represent a wide range of shear bond connection characteristics. Slenderness ratio is defined as the span length divided by the total composite slab depth. The effects of eleven parameters are investigated for each decking and slenderness. Effects studied include the load‐carrying capacity at service deflection limits (L/250), ultimate deflection limits (L/50), and maximum load‐carrying capacity.

Flexural tests of two full-scale composite trusses

Steel trusses acting compositely with concrete slabs on wide rib profile steel deck have proven to be an economical system for long span floors. The flexural behaviour of two composite trusses with a span of 11.5 m was studied. The truss configuration consisted of hollow structural section chords with double angle web members welded on either side. The flexural tests showed that ductile behaviour up to failure can be obtained without failure of the web members, provided that the design is based on the ultimate tensile strength of the bottom chord, and the web members and shear connection are designed for the concomitant forces. The maximum moments attained were about 1.2 times the unfactored ultimate moment predicted by CSA Standard S16.1. The maximum strain in the bottom chord of both trusses was significantly higher than the yield strain, but did not reach the ultimate strain due to premature shear connection failure. The failure mode of the first composite truss demonstrated the need for additional rules for establishing the length of stud shear connectors for use in slabs on ribbed deck, as has been incorporated in S16.1-M89. A design procedure for double angle web members was developed, based on the test results. Key words: behaviour, composite steel–concrete trusses, flexure, long span, ultimate moment resistance.