7/21/2019 Loads Acting on Formwork

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Loads acting on Formwork 

 

In Construction, the formwork has to bear, besides its own weight, the weight of wet concrete, the live load due

to labor, and the impact due to pouring concrete and workmen on it. The vibration caused due to vibrators used

to compact the concrete should also be taken care off. Thus, the design of the formwork is an essential part

during the construction of the building.

For the design of planks and joists in bending & shear, a live load including the impact may be taken as

!"kg#m$. It is however, usual to work with a small factor of safety in the design of formwork. The surfaces of

formwork should be dressed in such a manner that after deflection due to weight of concrete and reinforcement,

the surface remains hori%ontal, or as desired by the designer. The sheathing with full live load of !" kg#m$should not deflect more than ".' cm and the joists with ""kg#m$ of live load should not deflect more than

".'cm.

In the design of formwork for columns or walls, the hydrostatic pressure of the concrete should be taken

into account. This pressure depends upon the (uantity of water in the concrete, rate of pouring and the

temperature.

The hydrostatic pressure of the concrete increases with the following cases)*

•  Increase in (uantity of water in the mi+.

•  The smaller si%e of the aggregate.

•  The lower temperature.

•  The higher rate of pouring concrete.

If the concrete is poured in layers at an interval such that concrete has time to set, there will be very little

chance of bulging.

luminium as usual is not a very strong material. -o the basic elements of the formwork system are the

 panel which is a framework of e+truded aluminium sections welded to an aluminium sheet. It consists of high

strength special aluminium components. This produces a light weight panel with an e+cellent stiffness*to*

weight ratio, yielding minimal deflections when subjected to the load of weight concrete. The panels are

manufactured in standard si%es with non*standard elements produced to the re(uired si%e and si%e to suit the

 project re(uirements.