Effect of sanitary systems on strength of structures
Where ever proper planning is done
during construction sanitary vertical stakes are fixed on outer faces of walls.
But in the recent years a trend has
started to embed these pipes with in walls in smaller housing. For getting
better looks and creating designs inside the toilets and on the outer face from
elevation point of view these pipes are hidden by embedding. This causes these
pipes to pass through structural members such as beams at times in positions of
maximum shear or bending moment. Here even the rings provided for shear in
beams are shifted, totally twisted or cut to accommodate these pipes this can
be a major point of weakness at times of Earthquakes. Rings / stirrups take the
major brunt of the shear forces created by seismic forces and normal loading in case these are only cut or displaced from position then how safe is the
building.
Thus, care should be taken that
vertical sanitary stakes should not pass through beams. Where ever pipes cross beams,
the structural designer should be informed so that he adjusts the structure
accordingly.
In the case of walls chases are cut
indiscriminately in all directions i.e. horizontally and vertically in both
4.5" and 9" thick walls. This causes weakness in these walls, firstly
due to the hammering the mortar joint is weakened, secondly from where ever the
chase passes it creates a plane of weakness. These weaknesses can again become
fatal at the time of severe earthquakes.
Thus, it is very much necessary to
take approval of the structural designer w.r.t the position of vertical stakes
and the cutting of chases in load bearing brick walls. If possible provide the
G.I pipes on the surface of walls as was the practice in C.P.W.D during the
good old days..
It is always advisable to provide
the vertical stakes outside the wall since in case of earthquake if these pipes
are affected then it would be easy to repair them without breaking the wall and
secondly this would not weaken the structural frame.
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