Rolling Stock > Structural Model > WIB

Definition of the structural system to be analyzed. The tool allows for analyzing some standard types of bridge structures and up to a certain size also models specified in the analysis program RM. The actual type of the structure to be analyzed is selected in the pull-down menu of the input field Model Type.

Setting	Description
WIB	The structure is a so called WIB (filler beam) structure, where standard rolled sections are arranged in longitudinal direction in a plate-like single span concrete structure. The structure is statically determinately supported on both ends, either line-like over the whole width or in2 points at prescribed distances from the edges. The program creates an equivalent girder grid with composite beams and concrete cross beams. An orthogonal grid is assumed (support lines normal to longitudinal direction).

Setting

Description

WIB

The structure is a so called WIB (filler beam) structure, where standard rolled sections are arranged in longitudinal direction in a plate-like single span concrete structure. The structure is statically determinately supported on both ends, either line-like over the whole width or in2 points at prescribed distances from the edges. The program creates an equivalent girder grid with composite beams and concrete cross beams. An orthogonal grid is assumed (support lines normal to longitudinal direction).

Plate Input

Definition of the parameters specifying the structure geometry and material properties

Setting	Description
Span length L	Clear length between the support lines
Plate width W	Width of the concrete plate (Number of steel profiles times distance between)
Thickness plate T	Thickness of the concrete plate
Excess length EL	Excess length of the plate beyond the support line
Amount of Steel girders	Number of encased rolled steel sections (max. 14). It is assumed, that the bottom face of the steel section is flush with the bottom face of the concrete plate. The distance between the profiles is assumed constant.
E-Modulus Steel	Young's modulus of the material of the rolled sections. The shear modulus is calculated with G=E(2*(1+ny)) with ny=0.3
E-Modulus Concrete	Young's modulus of the material of the concrete plate. The shear modulus is calculated with G=E(2*(1+ny)) with ny=0.2

Support Conditions

Definition of the parameters specifying the support conditions

Setting	Description
Continuously supported / Single Bearings	Selection of one of the alternatives "Line support" or "Support in 4 points"
Stiffness vertical	Spring constant for the vertical displacement (for each bearing, in the case of line support, bearings with this stiffness are arranged below each longitudinal girder)
Stiffness horizontal	Spring constant for the horizontal displacement (for each bearing, springs in longitudinal direction in the left support line (superstructure begin), springs in lateral direction below the 1st longitudinal girder (node 101 and 117).
Position 1st Bearing PB1	Only for "Single Bearings": Distance of the bearing from the plate edge left - down
Position 2nd Bearing PB2	Only for "Single Bearings": Distance of the bearing from the plate edge left - up
Position 3rd Bearing PB3	Only for "Single Bearings": Distance of the bearing from the plate edge right - down
Position 4th Bearing PB4	Only for "Single Bearings": Distance of the bearing from the plate edge right - up Note: All bearings are assumed to be located at a depth of 10 cm below the bottom face of the plate, i.e. a 10 cm cross girder along the support line is assumed.

Steel Cross-Section

Definition of the cross-section properties of the encased steel profiles. I-profiles of the series HEA, HEB and HEM can be handled and I-profiles with user defined geometry parameters.

Setting	Description
Girder Type	Name of the steel section (selection from the pull-down menu). If the file girdertypes.inp is not found in the program or project directory, the geometric parameters described below can be directly entered.
Width WS	Flange width of the double T section
Height HS	Total depth of the cross-section of the double T section
Thickness web TW	Thickness of the web of the double T section
Thickness flange TF	Thickness of the flanges of the double T section
Radius R	Transition radius from the web to the flange

Loading

Definition of the effective masses of the bridge. The selfweight of the load bearing structure ist calculated automatically within the program. Used specific weights: 25 kN/m3 for concrete, 78.5 kN/m3 for steel (fix).

Setting	Description
Ballast and Rail mass	Additional weight on the structure in kN/m2 (applied on the whole surface of the plate). Note: The mass definition is done by specifying respective weights. The conversion to mass quantities is done with using the fix value 9.81 m/s2 as gravity constant.
Left girder mass GML	Consideration of the mass of a possible non bearing edge beam. The mass is applied as a concentric line load on the leftmost (view in positive longitudinal direction) girder (no eccentricity and no rotational mass moment of inertia). The conversion to a mass quantity is done with using the fix value 9.81 m/s2 as gravity constant.
Right girder mass GMR	Consideration of the mass of a possible non bearing edge beam. The mass is applied as a concentric line load on the rightmost (view in positive longitudinal direction) girder (no eccentricity and no rotational mass moment of inertia). The conversion to a mass quantity is done with using the fix value 9.81 m/s2 as gravity constant.
Begin ramp	Length of the region, where a load becomes gradually effective at the first node while it approaches the begin of the bridge. This avoids the consideration of sudden impacts causing unrealistic results.
End ramp	Length of the region, where a load gradually looses its effect on the last node after it has left the bridge structure. This avoids the consideration of sudden impacts causing unrealistic results.
Number of Composite gir.	Number of the steel profiles encased in the concrete plate (no user specification, is internally set equal to the number of steel girders. The total plate width is divided by this number; this gives the width of the individual longitudinal girders, where the steel sections are arranged in the center at bottom. The stiffness and mass parameters of these composite girders are calculated and used in the analysis.
Damping (%)	Damping coefficient as percentage of the critical damping Note: The program uses Rayleigh damping, where the damping matrix is a linear combination of the stiffness matrix and the mass matrix (C = alphaM + betaK). In this approach, the equivalent damping ratio is varying with the frequency. The coefficients alpha and beta are calculated in the program such that the given damping ratio is exact for the angular frequencies w1 and w2 (in rad/s). Modes with frequencies between these values are slightly less damped, those with frequencies outside this region are damped to a higher extent.
w1(rad/s), w2(rad(s)	Relevant angular frequencies for calculating the Rayleigh damping coefficients. w1 shall be the first relevant Eigenfrequency, w2 the 2nd relevant frequency. Damping assumption is on the save side if the value of w2 related to a higher frequency. Default: w1=61, w2=157 (10.0 and 25 Hz)

Eccentricities

Definition of the axle load distribution over the width of the plate

Setting	Description
Track load factor (1-14)	These factors define the distribution of the axle load over the different longitudinal girders in accordance with the position of the track on the cross-section and the width of the crossties.