...
Input options for all bearing information can be found on the Structural Model tab.
Input Name | Description |
|---|---|
Distance from start / end | The distance from the end of the member to the center line of bearing. This value is also used as s for the plain bearing capacity calculation |
Length | The length of bearing area in the longitudinal direction |
Width | The width of the bearing area in the transverse direction |
Friction Coeff. | The coefficient of friction |
A1 / A2 | The ratio of the bearing areas as defined in PCI 5.5.1. |
Bearing Points | The number of points at each end of the member which support the component. IE for a double T this would be 2. |
Nu / Vu Ratio | The ratio used to calculate Nu and Cr. This ratio is only applied to the sustained load. |
User defined Cr | If the user selected ‘Override Cr’ they can input their own Cr value to use. Note that the Nu / Vu ratio will still be used to compute Nu. |
Plain Bearing Capacity
The plain bearing capacity is calculated based on Ch. 5 Section 5.5.1. For this calculation it is assumed that Nu is equal to 0.2 times the reaction, that is that Nu = 0. 2 Vu. When calculating the Cr term, the distance from the start (or end) is used for the s term in Eq. 5-61.
...
In the above equations, Acr is calculated as the sections height times the bearing width and it is still assumed that Nu is equal to 0.2 times the reaction.
...
Applied Reaction
The above calculations refer the Vu throughout the free body diagrams and within the equations themselves. This Vu however, is the applied end reaction at the member, not the maximum shear force coming from the shear diagrams. This is because, per ACI 318-14, The applied load at the ends of the member can, at times, but assumed to go directly into the support, because of this the maximum Vu is less than the end reaction.
...
If your member has multiple bearing points, the bearing geometry should be input as the total a single bearing pad’s geometry. For example, if you are designing a stadium riser that is bearing on two legs, the bearing width should be the total width of all bearing pads, not a single individual one. By by doing this, the A1 and Acr values in each equation will be appropriately doubled.If the member is a T-Beam type section (as defined on the concrete extents) the bearing geometry is assumed to be input per stemcalculated appropriately.