Model elastomeric bearing in midas civil

#Model elastomeric bearing in midas civil free#

#Model elastomeric bearing in midas civil free#

A free (multidirectional) bearing is provided for the diagonally opposite corner to the fixed bearing. The bridge deck is fixed in one corner and horizontal movements are controlled by the use of guided (unidirectional) bearings. The arrangement above shows the layout for a simple single span structure with skew. Simple bridge bearing layout (single span on pot bearings) All horizontal forces and movements are then accommodated by shear deformation of the bearings. The bearings for this articulation arrangement will be elastomeric bearings. If a bridge deck is relatively small and the associated horizontal forces are not too big, the deck can effectively вЂњfloatвЂќ on bearings that will each accommodate rotational and translational displacements and will each provide part of the resistance to horizontal forces. Single span bridges Floating articulation The symbols for elastomeric pot bearings will be solid black, rather than an open square and circle. Note: Some symbols are due to be modified in a future amendment of BS EN 1337-1. Pot bearing with multidirectional sliding Symbols for common bearing types (from Table 1 of BS EN 1337-1 ) Symbol in planД®lastomeric bearing with restraints for one axis

A selection of common symbols is given below. The convention for illustrating the movements and constraints in bearings is given in Table 1 of BS EN 1337-1. The articulation scheme that the designer chooses should be shown on the drawings and will form the basis of a bearing schedule. The construction sequence of the structure should also be considered, to establish the permanent displacements. Similarly, restraint against transverse forces should be provided at only one bearing at each support.

Restraint against longitudinal forces should be provided at one support, with guided restraints aligned to allow movement at the other supports. The designer should avoid locking in forces that would hinder bearing replacement. Spans should be arranged so as to avoid uplift at bearing positions (it is a very complex and costly matter to provide restraint against uplift in a bearing), particularly when dealing with skewed structures. The following recommendations relate to the articulation arrangements for typical highway bridges.ДЄs bearings and expansion joints introduce a maintenance liability, it is good practice to limit the number of bearings required and to minimise the movement to be accommodated by an expansion joint. Since it is necessary to resist horizontal forces at at least one position, it is usual to do so by preventing horizontal displacement at that position this means that horizontal displacements at other positions are due to the expansion/contraction of the length from the fixed bearing and to the (vectorial) sum of the movements due to bending rotation. Horizontal displacements at supports arise both from an overall change in length of the structure and due to bending in a vertical plane (since the centroidal axes are above the levels of the supports). In some cases, there is also a rotation about a vertical axis (associated with plan bending of the structure) but this is usually small in magnitude. Generally, the structure will rotate about longitudinal and transverse axes at its supports and these rotations must either be accommodated in the bearings or the bearings must be designed to resist them (in which case the effects on the structure must also be considered). Movements can be either permanent (irreversible) or transient (reversible). Accidental actions - vehicular collision.Variable actions вЂ“ mainly traffic loads.Permanent actions (dead loads and superimposed dead loads).Temperature change (uniform and temperature difference).The principal actions that give rise to displacements and rotations at supports are: 5.1 Initial temperature and temperature rangeД«earings are used to transfer forces from the superstructure to the substructure whilst either tolerating or constraining relative movement.