Load Train > Uniform and Concentrated Load

A Load Train is a series of uniform loads and concentrated loads to be applied at the respective lane such that it has the worst influence on the considered result value. The series consists of an arbitrary number of sections (blocks) with a certain uniform load intensity and a concentric load at the begin of the block.

Load trains are applied on the structure in the specified order from lane begin to lane end, i.e. as if the train is moved over the lane from the end to the begin. Asymmetric load trains are not automatically applied in mirrored configuration. If this is required, a separate mirrored load train has to be specified.

Note: Blocks with free length must be defined at the begin and end of the load series.This allows for specifying a uniform load from the begin of the lane to the begin of the actual heavy loading group or from the end of the heavy loading group to the end of the lane respectively.

Setting	Description
Q	Load intensity of the uniform load along the block length. The direction of the loading is defined as lane parameter in the lane definition pad. Pay attention to the sign definition: Lane definition macros always generate positive axis directions as load directions, i.e. in the case of vertical loading, Q (and/or F) must always be defined as a negative value. Note: Q will only be applied in those sections where it acts unfavorably. This is indicated by the string Var in the row q-Flag of the respective table and in the GUI by the respective hint below Q. Uniform loads acting unconditionally over the whole block length are currently not implemented. Attention: Currently the uniform load must have the same intensity in all blocks, or the value 0.0 in sections without loading.
Q-fav	Load intensity of the uniform load along the block length which will be applied in those sections where it acts favorably. Attention: Load will be considered only if it is checked in check box near to the field for value input.
qu	Alternative definition of the load intensity as uniform surface load. The width wu of the loaded strip must in this case be properly defined.
wu	Width of the strip of the defined uniform surface load distributed in lateral direction.
F	Concentrated load at the begin of the block. Load direction as for Q. Normally the load is an axle load applied in the center of the lane. Internal division of the load F into wheel loads can be specified by entering wc, dl, dt. Note: Concentrated loads are normally unconditionally applied, i.e. also when they act favorably. This is indicated by the string Fix in the row F-Flag of the respective table. The option LRFD can be used to specify, that the load F shall only be applied when it acts unfavorably.
qc	Just for information in case of specification of wheel loads: Load intensity of the uniform surface load acting on the wheel-roadway contact area.
wc	Distance of the 2 wheels of the axle (distance of center points of the contact areas)
dl	Dimension of the rectangular contact area in longitudinal direction
dt	Dimension of the rectangular contact area in transversal direction Note: 2qcdl*dt must be equal to F. If dl and dt are specified other than zero, the program calculates for information only the wheel pressure qc by using qc=F/2/dl/dt. Attention: The actual values of dl and dt are not used in the influence surface evaluation. The program always calculates with concentrated wheel load of magnitude F/2.
AASTHO	Only for hogging moments (negative Mz values): F is not only applied in the span where it has the worst influence, but also a 2nd time in the neighbor span. The minimum distance specified in the AASHTO design code is considered and the load only applied if acting unfavorably.
LRFD	Concentrated loads are normally unconditionally applied, i.e. also when they act favorably. The option LRFD allows for specifying that the load F shall only be applied when it acts unfavorably.
Free length	The block length is unlimited, i.e. it extends to the end of the lane or - if it is the 1st_ block - from the begin of the lane to the begin of the next block. Note: Option only allowed for the first and last block.
L-from, L-to, L-step	Variation of the block length in the range l-from, l-to and l-step. The length is varied in steps. In principle, the corresponding different load trains are investigated and the most unfavorable selected. If there are several blocks with variable length and/or a very small step length l-step, the required computing time may increase considerably.