Load take down

For any structure it is important to understand how the vertical load transfers down

through the structural system.

Consider the frame for a reinforced concrete and steel office building. It has $4$ storeys and it

has been designed on a $6$mxx$8$m grid. The overall structure is $3$ bays by $5$ bays so the total

plan dimensions are $18$mxx$40$m$.$ Each storey height is $3$ m $.$ See accompanying sketches.

The reinforced concrete slab has been designed to span in one direction, $6$ m $,$ and

preliminary sizing suggests it is $250$ mm deep. The slab is supported by steel beams which

span $8$ m between steel columns. There are transverse beams, parallel to the slab span, for

column stability only.

There should be an additional dead load allowance of $1\mathrm{.}5$kN$//$m$^(2)$ included for floor finishes

and services.

It is important for the design of structural members that ultimate factored $($ULS$)$ loads are

used, however, for foundation design unfactored $($SLS$)$ loads are required. Therefore, both

factored and unfactored loads need to be worked down through the system.

Do a load path analysis for the structure.

You will need to work through the following steps:

Determine the UDL live loading for the office floor from Eurocode $1$

Determine the total combined slab load $($both ULS and SLS are required$)$

Determine the linear UDL on the primary beams supporting the slab $($both ULS and

SLS are required for both an internal and a perimeter beam$)$

Determine the Max. ULS bending moment for one internal beam and one perimeter

beam

Determine the beam end reactions and accumulative column axial loads.

Provide a detailed plan of the column bases with the total SLS and ULS loads labelled

on each column base.

Please use $2\mathrm{.}5$kN$/$m$^2$ as the office floors live loading. Also, note that you have to calculate the ULS and SLS for the normal floors separately to the ULS and SLS for the roof $($which will just have the snow live loading of $0\mathrm{.}6$kN$/$m$^2)$ Figure $2,$ section of structural frame