Write short notes on architectural features which govern the design of building against earthquake force
Formwork is the term used for the process of creating a temporary mould into which concrete is poured and formed. Traditional formwork is fabricated using timber, but it can also be constructed from steel, glass fibre reinforced plastics and other materials. There are three types of formwork :- -BeaRead more
Formwork is the term used for the process of creating a temporary mould into which concrete is poured and formed. Traditional formwork is fabricated using timber, but it can also be constructed from steel, glass fibre reinforced plastics and other materials.
There are three types of formwork :-
-Beam formwork :-
Formwork for beams takes the form of a three-sided box which is supported and propped in the correct position and to the desired level. The removal time for the formwork will vary with air temperature, humidity and consequent curing rate. Typical striking times are as follows (using air temperature of 7-16 ºC):
i) Beam sides: 9-12 hours.
ii) Beam soffits: 8-14 days.
iii) Beam props: 15-21 days.
-Column formwork :-
This consists of a vertical mould of the desired shape and size of the column to be poured. As a means of keeping the formwork material thickness to a minimum, horizontal steel or timber clamps (or yokes) are used at equal centres for batch filling and at varying centres for filling that is completed in one pour.
The head of the column formwork can be used to provide support for the beam formwork, but while this gives good top lateral restraint it can make the formwork complex. Alternatively, the column can be cast to the underside of the beams. Later on, a collar of formwork can be clamped around the cast column to complete the casting and support the incoming beam formwork.
-Plastic formwork :-
Re-usable plastic formwork is generally used for quick pours of concrete. The formwork is assembled either from interlocking panels or from a modular system and is used for relatively simple concrete structures. It is not as versatile as timber formwork due to the prefabrication requirements and is best suited for lost-cost, repetitive structures such as mass housing schemes.
Stay-in-place structural formwork is generally assembled on site using prefabricated fibre-reinforced plastic. It is used for concrete columns and piers and stays in place, acting as permanent axial and shear reinforcement for the structural member. It also provides resistance to environmental damage for both the concrete and reinforcing bars.
Proprietary systems are used to support vertical formwork while concrete cures, consisting of a series of tubes and ties.
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aviratdhodare
Such that the forces generated by the most destructive force that The Mother unleashes upon us human, tenets of Earthquake Resistant design need to be incorporated into all buildings we live and work within. For ensuring the safety of people there, it must be ensured by the designers that the buildiRead more
Such that the forces generated by the most destructive force that The Mother unleashes upon us human, tenets of Earthquake Resistant design need to be incorporated into all buildings we live and work within. For ensuring the safety of people there, it must be ensured by the designers that the buildings don’t collapse in the event of an earthquake. Towards this end, the technical aspect of endurance is – ductility. We shall see that a little later.
Before proceeding on any elaboration, let the concerned reduce the contradictions/conflicts that nearly regularly surface between the Architects and the Structural Engineers.
As far as Architectural features are concerned, these are a few of them that must be incorporated. For example, keep the plan symmetrical along its vertical axis and avoid large void spaces within the buildings.
If architects can take the structural engineers along with them right from the beginning of the architectural planning process, much of the confrontations and changes at later stages can be obviated. Else, the cost for the same size building can be much higher if the architect insists upon very peculiar shapes. Unfortunately, this seamless coordination between these two prime people doesn’t happen in most cases.
The challenge is much bigger for the structural designers if the owner and the architects insist upon peculiar designs. The Burj Al Arab Hotel of Dubai is one example. Imagine, everything right from the beginning has been and shall ever remain against the stability of this particular building. Yet it stands. More than the architect, it is the structural designer who needs to be applauded for this magic…
Structural designers must design buildings such that while the columns and the beams are strong, the roof slabs be as light as is feasible given the architectural shape/design of any building.
Confining reinforcement at the beam-column junctions ensures the required ductility of the buildings in the event of an earthquake. This MUST be ensured at all costs.
There are numerous other features of the design. But equally significant part is the execution of the design on the ground. Unfortunately, we in India are not able to control this part very well.
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