Revisiting arching in deck slabs

1996 ◽  
Vol 23 (4) ◽  
pp. 973-981 ◽  
Author(s):  
Baidar Bakht
Keyword(s):  
Design Method ◽  
Field Tests ◽  
Scale Model ◽  
Girder Bridges ◽  
Transverse Arch ◽  
Deck Slabs ◽  
Arching Action ◽  
Girder Bridge ◽  
Concrete Deck ◽  
Deck Slab

The arching action in concrete deck slabs of girder bridges is generally recognized and is utilized by the Ontario Highway Bridge Design Code, and some other codes, to specify an empirical design method which leads to considerable savings in the amount of reinforcement. Despite this general recognition, there are some aspects of the arching action that are yet to be explored. To the knowledge of the author, all reported laboratory and field tests on deck slabs exploring its arching action under applied loads have been conducted by measuring strains in the bottom transverse reinforcement midway between the girders. Based on the results of tests on a full-scale model of a deck slab, it has been confirmed in this note that the transverse bottom reinforcement in the deck slab acts as a tie to the internal transverse arch in the slab. Because of embedment in concrete, the force in this reinforcement is the smallest midway between the girders, and not the largest as would be the case if the slab were in pure bending. Key words: arching in slabs, deck slabs, girder bridge, punching shear, steel-free deck slabs.

Experimental investigation of the role of reinforcement in the strength of concrete deck slabs

2000 ◽  
Vol 27 (3) ◽  
pp. 475-480 ◽  
Author(s):  
O Shervan Khanna ◽  
Aftab A Mufti ◽  
Baidar Bakht
Keyword(s):  
Steel Reinforcement ◽  
Scale Model ◽  
Transverse Reinforcement ◽  
Deck Slabs ◽  
Steel Bars ◽  
Failure Loads ◽  
Transverse Steel ◽  
Concrete Deck ◽  
Deck Slab

To study systematically the role of each layer of steel reinforcement in conventionally reinforced deck slabs of girder bridges, a full-scale model was built of a 175 mm thick concrete deck slab on two steel girders with a center-to-center spacing of 2.0 m. The 12 m long deck slab was conceptually divided into four 3 m long segments, identified as segments A, B, C, and D. Segment A contained isotropic steel reinforcement in two layers, conforming to the requirements of the Ontario Highway Bridge Design Code (OHBDC). Segment B contained only the bottom layer of steel reinforcement. Segment C contained only the bottom transverse steel bars. Segment D contained only bottom transverse glass fibre reinforced polymer (GFRP) bars having the same axial stiffness, but 8.6 times the axial tensile strength, as those of the steel bars in segment C. Each segment of the deck slab was tested to failure under a central concentrated load, simulating the dual tire footprint of 250 × 500 mm dimension of a typical commercial vehicle. All segments failed in the punching shear mode. The failure loads for the four segments were found to be 808, 792, 882, and 756 kN, respectively; these failure loads are similar in magnitude to that of a 175 mm thick steel-free deck slab with steel straps having nearly the same cross-sectional area per metre length of the slab as those of the bottom transverse steel bars in the first three segments. The tests on the four segments of the full-scale model have confirmed that (i) only the bottom transverse reinforcement influences the load carrying capacity of a reinforced concrete deck slab and (ii) the stiffness of the bottom transverse reinforcement, rather than its strength, is of paramount importance.Key words: arching, deck slab, FRP, shake down, slab-on-girder bridge.

Deck slabs of skew girder bridges

1995 ◽  
Vol 22 (3) ◽  
pp. 514-523 ◽  
Author(s):  
Baidar Bakht ◽  
Akhilesh C. Agarwal
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Shear Failure ◽  
Highway Bridges ◽  
Steel Reinforcement ◽  
Fibre Reinforced Concrete ◽  
Girder Bridges ◽  
Deck Slabs ◽  
Concrete Deck ◽  
Deck Slab

Canadian codes allow the design of concrete deck slabs of slab-on-girder bridges by taking account of the internal arching action that develops in these slabs under concentrated wheel loads in particular. Provided that certain prescribed conditions are met, a deck slab is deemed to have met the design criteria if it is provided with a top and a bottom layer of steel reinforcement with each layer consisting of an orthogonal mesh of steel bars in which the area of cross section of the bars in each direction is at least 0.3% of the effective area of cross section of the deck slab. For deck slabs of bridges having skew angles greater than 20°, the codes require the minimum amount of reinforcement to be doubled in the end zones near the skew supports. Model testing has shown that need for such an increase can be eliminated by providing composite end diaphragms with high flexural rigidity in the horizontal plane. The proposed concept is tested on a model of fibre-reinforced concrete deck without steel reinforcement in which deficiencies in the confinement of the deck slab readily manifest themselves in form of a bending, rather than punching shear, failure. Key words: highway bridges, bridge decks, deck slabs, skew deck, skew bridges, fibre-reinforced concrete decks.

Testing in isolation of transverse confining systems for steel-free deck slabs

1998 ◽  
Vol 25 (4) ◽  
pp. 789-796 ◽  
Author(s):  
Baidar Bakht ◽  
Ahmed Aly
Keyword(s):  
Mirror Image ◽  
Axial Stiffness ◽  
Connection Strength ◽  
Girder Bridges ◽  
Pull Out ◽  
Deck Slabs ◽  
Different Types ◽  
Image Models ◽  
Girder Bridge ◽  
Deck Slab

The provisions of the forthcoming Canadian Highway Bridge Design Code are noted for the design of the external transverse confining system for steel-free deck slabs of girder bridges; according to these provisions, the transverse straps comprising the confining system are required to have a certain minimum axial stiffness, and their connection strength with the deck slab is also specified. The axial stiffness of the straps and their connection strength were studied with the help of pull-out tests on mirror-image models of isolated segments of the deck slab and four different types of strap systems. Three of the tested systems were found to be adequate, and the fourth was considered inadequate because of insufficient connection strength.Key words: arching in slabs, cruciform strap, deck slab, girder bridge, partially studded strap, punching shear, steel-free deck slab, transverse confinement.

Steel Girder Bridge with RC Deck Retrofit From Non-Composite to Composite Behaviour

2016 ◽  
Author(s):  
Abheetha Peiris ◽  
Issam Elias Harik
Keyword(s):  
Field Tests ◽  
High Strength ◽  
The United States ◽  
Field Application ◽  
Steel Girder ◽  
Shear Connectors ◽  
Before And After ◽  
Steel Girder Bridge ◽  
Girder Bridge ◽  
Concrete Deck

In the past, a number of steel girder-reinforced concrete deck bridges on county roads in the United States have been built as non-composite. Most of these bridges currently have load postings limiting the capacity of bus and truck loads on their roadways. Recent research showed that post installed high strength bolts could be used as shear connectors in rehabilitation work to achieve partial composite design by deploying 30% to 50% of the connectors typically required for a full composite design. This paper presents details on the analysis, design, and field application of post-installed shear connectors on a non-composite concrete deck steel girder bridge in Kentucky. In order to minimize traffic disruption and construction costs, the shear connectors were inserted on the bottom side of the deck through the top flange of the steel girder. While the load rating increased by 132%, field tests conducted before and after installation of the shear connectors showed that the bridge's live load deflections were reduced by more than 27%.

Test and Numerical Study on the Seismic Performance of A Cable Restrainer for Girder Bridges

2019 ◽  
Author(s):  
Yitong Gu ◽  
Wancheng Yuan ◽  
Xinzhi Dang
Keyword(s):  
Seismic Performance ◽  
Numerical Study ◽  
Design Method ◽  
Lateral Displacement ◽  
Static Test ◽  
Girder Bridges ◽  
Continuous Girder Bridge ◽  
Service Conditions ◽  
Girder Bridge ◽  
Parametric Analyses

<p>In China, most of the support systems applied by short/medium span bridges are elastomeric pad bearings (EPBs). This type of support system has no reliable connections between bearings and girders as well as bearings and piers, which will cause structural damages due to large lateral displacement of bearings under earthquakes. The restrainers used currently could restrict the deformation of bridges under normal service conditions and could only restrict unidirectional displacement. Considering the disadvantages of these restrainers, a new restrainer called Connected Cable Restrainer (CCR), which can be used in short/medium span bridges supported by EPBs, is developed in this paper. The design principle, basic configuration, isolation mechanism and the design method of CCR are introduced. A pseudo static test to study the seismic performance of CCR is conducted. Seismic responses of a 3-span continuous girder bridge with CCR are simulated using OpenSees platform and parametric analyses of the two main parameters, lateral restraining displacement and restraining stiffness, are also carried out. Results show that the deformation of bridges under normal service conditions would not be restrained using CCR and the displacement responses can be mitigated effectively by using CCR through parameter optimization.</p>

Fibre-reinforced polymer composite bars for the concrete deck slab of Wotton Bridge

2003 ◽  
Vol 30 (5) ◽  
pp. 861-870 ◽  
Author(s):  
Ehab El-Salakawy ◽  
Brahim Benmokrane ◽  
Gérard Desgagné
Keyword(s):  
Field Test ◽  
Remote Monitoring ◽  
Concrete Bridges ◽  
Fibre Optic ◽  
Reinforced Polymer ◽  
Deck Slabs ◽  
Fibre Reinforced Polymer ◽  
Concrete Deck ◽  
Frp Bars ◽  
Deck Slab

A new concrete bridge in the Municipality of Wotton, Quebec, Canada, was constructed using fibre-reinforced polymer (FRP) bars as reinforcement for the deck slab. The new bridge is a girder type with four main girders simply supported over a span of 30.60 m. One half of the concrete deck slab was reinforced with carbon and glass FRP bars, and the other half with conventional steel bars. The design of the reinforced concrete deck slab was made according to sections 8 and 16 of the new Canadian Highway Bridge Design Code. The bridge was well instrumented at critical locations for long-term internal temperature and strain data collection using fibre optic sensors. The construction of the bridge was completed and the bridge opened for traffic in October 2001. The bridge was then tested for service performance using standard truckloads. Design, construction details, and the results of the field test and 1 year of remote monitoring are discussed. Under the same real service and environmental conditions, very similar behaviour was obtained from the FRP (glass and carbon) and steel bars.Key words: concrete bridges, deck slabs, FRP bars, field test, fibre optic sensors, remote monitoring, serviceability.

Application of Expansion Double Spherical Seismic Isolation Bearing in Seismic Design of Continuous Girder Bridges

2011 ◽  
Vol 243-249 ◽  
pp. 1928-1934 ◽  
Author(s):  
Tian Bo Peng ◽  
Zhen Nan Wang ◽  
Xun Tao Yu ◽  
Cheng Yu Yang
Keyword(s):  
Seismic Design ◽  
Seismic Isolation ◽  
Seismic Analysis ◽  
Design Method ◽  
Longitudinal Direction ◽  
Vertical Displacement ◽  
Girder Bridges ◽  
Earthquake Effect ◽  
Continuous Girder Bridge ◽  
Girder Bridge

The double spherical seismic isolation (DSSI for short) bearing has been adopted in seismic design of several important engineering projects since developed recently. It was used generally as fixed bearings in a continuous girder bridge in these projects, and only a few fixed piers, usually just one fixed pier would transmit the horizontal earthquake action to the foundation, which is uneconomical and results in the much larger seismic risk in the longitudinal direction of a continuous girder bridge than that in the transverse direction. In order to share the earthquake effect with all the piers and avoid relative vertical displacement among all the bearings under the normal traffic conditions, a new seismic design method of continuous girder bridges is introduced. The configuration and working mechanism of two kinds of DSSI bearings used to make the new seismic design possible are introduced. It’s shown that the method is preferable for the seismic design of continuous girder bridges by a numerical seismic analysis with a four-span continuous girder bridge.

Investigation of an externally restrained concrete bridge deck slab on a multi-girder bridge model

2011 ◽  
Vol 38 (2) ◽  
pp. 233-241 ◽  
Author(s):  
John Newhook ◽  
Judy Gaudet ◽  
Rahman Edalatmanesh
Keyword(s):  
Bridge Deck ◽  
Single Point ◽  
Point Load ◽  
Concrete Bridge ◽  
Simultaneous Application ◽  
Bridge Model ◽  
Deck Slabs ◽  
Concrete Bridge Deck ◽  
Girder Bridge ◽  
Deck Slab

The steel-free bridge deck system is an innovative solution in which the concrete deck slab is externally restrained by a series of steel straps. The ultimate strength characteristics of externally reinforced concrete bridge deck slabs were investigated in this paper. A 1/3 scale experimental model of a bridge with six girders was constructed for the study. This was the first known set of test results on a bridge model with more than four girders. A single point load, simulating the dual tire print of the CHBDC design truck, was applied at various locations on the deck and loading increased until punching failure occurred. The influence of different parameters including transverse diaphragms, proximity for the load to restraint straps, residual strength after strap removal, and simultaneous application of wheel loads in adjacent panels of the deck was tested to obtain a comprehensive understanding of the resistance of this deck system. The testing results confirmed that the interior panels of the deck have inherently higher punching resistance than the exterior panels. Most significantly, the study provided significant statistical data on the punching resistance of these deck slabs.

Study of the Effect on Efficiency of External Prestressing and Economy to Box-Girder Bridge with Different Styles of Webs

2012 ◽  
Vol 256-259 ◽  
pp. 1605-1608
Author(s):  
Jin Song Zhu ◽  
Jian Feng Li
Keyword(s):  
Life Cycle Cost ◽  
Quantitative Research ◽  
Design Method ◽  
Structural Performance ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Girder Bridges ◽  
External Prestressing ◽  
Box Girder Bridge ◽  
Girder Bridge

Prestressed box-girder bridges have been applied in modern bridges widely as the perfect structural performance, the design method and calculation theory of prestressed box-girder bridges have been relatively perfect. The self-weight of box-girder bridges is reduced during the process of development from concrete structure to composite structure. The prestressed efficiency and the economy are also improved, simultaneously. But up to now, the quantitative research of the effect on efficiency of external prestressing to box-girder bridge with different styles of webs is lack. This paper illustrates the effect on efficiency of external prestressing and economy to box-girder bridge with different styles of webs. The results show that the box-girder bridge with corrugated steel webs has the highest prestressed efficiency and the lowest life cycle cost and the best economy.

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