A simply supported beam, spanning 13m, forming part of the floor structure for an office
is required to support a UDI. and a point load as shown in Figure 1. Both the UDL and point load are downwards loads applied to the top flange, at the same time. Table A gives the magnitude of the permanent and imposed actions for the UDI. and point load.
A lateral restraint is provided to the bottom flange at point 8 and to the flange at point C as
shown in Figure 1 (lateral restraint denoted by X).
The beam is connected to adjacent support structures by web side plate connections which can be considered to provide full torsional and lateral restraint at each end of the member, but which provide no restraint against rotation in plan.
The serviceability limit state deflection criteria shall be taken to be span/500.
a) Determine the ultimate and serviceability actions acting on the beam.
b) Draw the 8MD and SFO for the ultimate load case.
c) Use the Design Capacity Tables (DCT) to select a standard Grade 300 013 or WB section for the beam. (Select the lightest section - only need to use a WB if no 118 beam Is large enough to satisfy the member requirements). Section capacity, member capacity, shear capacity, combined shear and bending, and deflection limitation (using the Wes method in DCT) must all be considered.
d) Check the web bearing capacity of the selected member at the point load. Assume the stiff bearing width at the point load Is 50mm. Are any stiffeners required?
e) Assume that there are two M20 bolts in each web side cleat (at the simply supported ends). Does the web of the beam have sufficient bearing capacity (ply in bearing) at the edge of the holes?
Table A
|
|
Permanent
|
Imposed
|
|
Point load (kN)
|
30
|
8
|
|
UDL (kN/m)
|
5
|
4
|
