The Structural Engineer's Corner

Eng. Onorio Francesco Salvatore

Archive for the 'Bridges' Category

Traffic loads on road bridges: division of the carriageway into notional lanes according to Australian Standard 5100.2


The load models defined in the Australian Standard 5100.2 shall be assumed to occupy one standard design lane of 3.2 m width. The number of standard design lanes is defined as: n = b / 3.2 (rounded down to next integer) where: – n = number of standard design loads; – b = width between […]

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Traffic loads on road bridges: a practical example


After the recent posts on the traffic loads as defined by EN 1991-2, let’s make an example. We have a bridge covering a span of 50.0 m with a static scheme of simple abutment. The roadway is 7.50 m wide flanked on each side by walkways having a width of 2.0 m. The walkways are […]

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Traffic loads on road bridges: the Load Model 4 (LM4) in Eurocodes


The Load Model 4, as defined in the EN 1991-2, is the crowd loading and is represented by a UDL equal to 5 kN/m². It includes dynamic amplification and in certain cases can be more critical than LM1. It has been found that LM4 > LM1 in the following cases:

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Traffic loads on road bridges: the Load Model 3 (LM3) in Eurocodes


Some road bridges must be designed against special traffic loads. This is the case of bridges that may experience a military use during their lifetime. The very conventional model used represents special vehicles that can exceptionally transit on bridges as abnormal vehicles. The application can concern one or several special vehicles. This case is detailed […]

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Traffic loads on road bridges: the Load Model 2 (LM2) in Eurocodes


The Load Model 2 (LM2) is a single axle model, which is applied when a local verification for short structural elements is required. Such elements can be crossbeams, upper flange stiffeners of othotropic decks or deck panels of composite slabs with steel sheeting. The internal forces due to LM2 may then be more critical compared […]

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Traffic loads on road bridges: the Load Model 1 (LM1) in Eurocodes


As discussed in the previous post, the Load Model 1 should be used for both global and local verifications. It is intended to cover flowing, congested or traffic jam situations with a high percentage of heavy lorries. In general, when used with the basic values, it covers the effects of a special vehicle of 600 […]

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Traffic loads on road bridges: the Traffic Load Models


In the Eurocodes there are four Traffic Load Models to be used for the determination of road traffic effects associated with Ultimate Limit and Serviceability Limit States. These load models for vertical loads represent different traffic effects. In short: – LOAD MODEL 1 (LM1):

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Traffic loads on road bridges: division of the carriageway into notional lanes according to Eurocodes


In this post we’ll discuss about the traffic loads on road bridges according to Eurocodes. The first step when evaluating the loads is the division of the carriageway into notional lanes. The width of the carriageway (w) has to be measured between the inner limits of vehicle restraint systems. Should not be included in the […]

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