Structural Design 5 - Loading of a building

 There are three major types of loading. Dead, Imposed and lateral loading. We have to clearly and correctly identify the loading nature and the values for a better analysis part. If the loading is not considered well, you will have either a very weak insufficient sizes for elements or an over-design which will lead for an unnecessary money loss to the client. We will look at those different different loading separately. 

(1). Dead loads. 

We call these immovable loads as well. Actually these are the still loads which are definitely act weather the building functioning or not.  We consider the brick weights, Block wall weights, Concrete weights (Self weight) and finishes weight for this load case. We consider the service dead load as it is and when conducting the design works we have to factorize it for an adverse dead load condition. Acoording to BS8110, it is 1.4

gk is used to denote a dead load in units of kN/m or kN/m2 (Dead load intensity)
Gk is usually used to denote a dead load in units of kN (Point dead load)

Here we have small simple examples for calculating the dead loads in two different situations.

(1). Imposed loads.(Live loads) 

We call these movable loads. The things inside utilizable areas including pets and humans in it are taken for live or imposed loads. According to the function of the different different floor areas imposed loads can be varied. As an example, inside a bed room usually 2-5 people can accommodate and relative it has a small imposed load. When we consider a lift machine room there is a relatively large imposed load since the weight of the machines used there are very large. Likewise we have to find the relevant imposed load for the areas. For that we can use a code in British standards. That is BS 6399. All the relevant live loads according to the functionalities are included in this loading code. Weather it is a school, factory or an office all the needed loads are indicated in that book. Since after fixing a partition is immovable, we can change the position and the amount of partitions anytime easily in the floors. So the partition loads are also taken in to imposed loads. In British codes, they have clearly mentioned that a safety factor of 1.6 is needed to taken in to account when converting a service imposed load in to a design or Ultimate imposed load. 

Sop finally we can take the final Design load by multiplying the dead load by 1.4 and multiplying the imposed load by 1,6 and by adding those together.

n=1.4gk+1.6qk

For an example, we can show below the column design philosophy. In that equation, we have the ultimate point or axial load on a column in left hand side. When finding it we have to find the dead loads and live loads on it and factor them and sum up them. That is shown in the below picture.

Now you have a good knowledge about loading. We can proceed these learning from here. Meet us on our next new lesson about Initial sizing of structural elements in Structural Design 6 Lesson. Until then follow our blog to receive the notifications.
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