We are accustomed, sometimes, to applying load to beams without giving much thought to the inherent stiffness of the load itself, either in the direction of the force or normal to it. Whether or not we consider arching of masonry is a matter of ‘engineering judgment', perhaps influenced by the requirements of BS 5977: Part 1:
Lintels. Studwork partitions have considerable load-relieving stiffness, which we wisely ignore, at least for strength considerations. Items of plant, such as water tanks, have inherent degrees of stiffness that, frequently, are able to distribute load towards the beam’s bearings. In a particular situation, it may be worthwhile
considering these factors when we make an ultimate or serviceability limit state assessment of a beam’s behaviour.