The grillage analogy in bridge analysis

Jaeger, Leslie G.; Bakht, Baidar

doi:10.1139/l82-025

Cited by 52 publications

(35 citation statements)

References 1 publication

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“…Normally, the longitudinal grillage members are placed coincident with the centerlines of bridge girders, while the bridge slab is divided into equivalent transverse beams. The number of these beams should be as large as possible with spacing not more than 1.5 times that of the longitudinal grillage members (West, 1973;Jaeger and Bakht, 1982). The section properties of the longitudinal grillage members are calculated in a manner similar that of composite T-beams.…”

Section: Bridge Modelmentioning

confidence: 99%

“…Figures 3(a) and (b) show a representation of a point load (wheel load) applied in between the four adjacent nodes and the corresponding equivalent nodal forces, respectively. Jaeger and Bakht (1982) recommended that wheel loads could be distributed linearly in the longitudinal direction ignoring any moments, and nonlinearly in the transverse direction to account for bending moments. Also, in an attempt to oversimplify the loading transformation, Chen (1994) simply assumed the wheel load distribution to be proportional to the tributary area without taking into account any moments in both longitudinal and transverse directions.…”

Section: Equivalent Nodal Loadsmentioning

confidence: 99%

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Analytical Modeling of Bridge-Road-Vehicle Dynamic Interaction System

Nassif

Liu²

2004

j vib control

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We present a three-dimensional (3D) dynamic model for the bridgeïroadïvehicle interaction system. A slab-on-girder bridge is modeled as a grillage system subjected to multiple moving truck loads. Multiaxle semi-tractorïtrailer is idealized as a 3D vehicle model with a nonlinear tireïsuspension system, having eleven independent degrees of freedom. Road roughness profiles are generated from the random Gaussian process as well as limited measurements of actual road profiles. Truck wheel loads are applied at any point and then transferred to nodes as equivalent nodal forces. The Newmark-q integration method is applied as a numerical algorithm for solving the bridgeïroadïvehicle dynamic interaction equations. The major parameters affecting the bridge dynamic response (or the dynamic load factor) include road roughness, truck weight, speed and mechanical properties of the tire-suspension system and bridge stiffness and boundary conditions. Results from other dynamic models as well as field tests are compared with those from the current 3D model. The results show that the dynamic load factor is highly dependent on road roughness, vehicle suspension, and bridge geometry.

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Section: Bridge Modelmentioning

confidence: 99%

Section: Equivalent Nodal Loadsmentioning

confidence: 99%

Analytical Modeling of Bridge-Road-Vehicle Dynamic Interaction System

Nassif

Liu²

2004

j vib control

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“…Grid layout and member properties must be chosen in a manner that will properly model the structural behaviour. Several authors have given guidelines on how to model bridge decks using the technique and interpret the results from such an analysis (Hambly 1976;Jaeger and Bakht 1982;OHBDC 1983;West 1973).…”

Section: Grillage Analysismentioning

confidence: 99%

Load distribution in edge stiffened slab and slab-on-girder bridge decks

Smith¹,

Mikelsteins²

1988

Can. J. Civ. Eng.

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The results of a study on the effect of edge beam geometry on the static live-load load distribution characteristics of single-span slab and slab-on-girder bridge superstructures are presented. Using a grillage analysis, the influence of various forms of edge stiffening on longitudinal bending moment and vertical deflection at midspan was investigated. Two load cases utilizing the Ontario Highway Bridge Design truck were considered. Of particular interest is the load case of a single vehicle in a travelled lane, as edge beam deflection under this condition is governed by a serviceability limit state design requirement of the Ontario Highway Bridge Design Code.For the bridge geometry and loadings considered, all types of edge stiffening significantly affect edge beam bending moment and deflection at midspan; the effect generally increases as the span decreases. Edge beam bending moment increases as the stiffness of the edge beam is increased. Considering the change in edge beam stiffness, edge beam deflection decreases even though the bending moment carried by the edge beam increases. The results of the grillage analysis agree well with an interpretation of the simplified method of analysis of the Ontario Highway Bridge Design Code. When the deflection criterion is affecting a bridge design, it would be beneficial to account for the edge stiffening.

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“…• It can be used in cases where the bridges exhibits complicating features such as a heavy skew, edge stiffening and deep hunches over supports • The representation of a bridge as a grillage is ideally suited to carrying out the necessary calculations associated with analysis and design on a digital computer • The grillage representation is conductive to giving the designer an idea bout the structure behavior of the bridge and the manner in which bridge loading is distributed and eventually taken to the supports [4].…”

Section: Introductionmentioning

confidence: 99%

“…Each of the longitudinal girders having flexural stiffness (EI), torsional stiffness (GJ) and length (L). The longitudinals girder are spaced a distance (h) apart and are interconnected by a number of equally spaced transverse beams each of which has flexural stiffness (EI T ) and torisonal stiffness (GJ T ) [4]. The other method used in modeling the bridges is the finite element method.…”

Section: Introductionmentioning

confidence: 99%