FORMWORK FOR SLABS,BEAMS AND STAIRS

PRESENTED BY:

RAKHI DEVRASHMI. RSUNIDHI MADHAVSWATHE

INTRODUCTION

Formwork for concrete structures has a significant impact on the cost, time, and quality of a completed construction project.

Formwork is the term given to either temporary or permanent moulds into which concrete or similar materials are poured

WoodPlywoodSteelAluminium PlasticPlasterSynthetics

materials

MATERIALS USED OBJECTTIVES

QUALITY

SAFETY

ECONOMY

REQUIREMENTS AND STAGES

Assembly and erection

Concrete placement

Stripping and dismantling

SLABS AND BEAMS

In a typical reinforced concrete building frame, the slabs are the primary load carrying element. They transfer their load tosecondary elements such as walls or beams.

TIMBER FORMWORK

BEAM FORM

 Installation of formwork for first floor slab and beams progressing all around the building

DISADVANTAGES

Easy Handling – LightweightEasy assemblingFlexibleEasy to produceRepaired parts can be easily replacedEasily available

Speed reduced for larger structures not many reusesMay asorb moisture from concreteShrinkage and warping

ADVANTAGES

CONVETION STYLE

INCORRECT BEHAVIOUR

SHUTTERING FOR SLABS WITH TIMBER BEAMS

FIXING THE FORMWORK

SUPPORT OF FORMWORK

Use of 18mm plywood sheets.In the construction of the slab and beam formwork, it is need to give a proper attention to the levels, shape and the alignment of the particular structural element. It is need to check the level at the initial state of erecting the formwork and before the concreting is done. Otherwise the level of the slab can change after the cast .So also, the stop boards at drops should be well positioned and fixed correctly before the concreting. Diesel should be applied inside of the formwork which is touched the concrete surface to easy removal of formwork. 

STEEL FORMWORK

Consists of panelsUsage of clamps, bolts and nutsPanels fabricated In large numberUsed I large projects ad where there are high number of reusesSuitable for circular ad curved structures.Limited size ad shape. Excessive heat lossLimited fixingUniform surfaceLarger spans ad more durale. Does not absorb water from concrete

LIGHT METAL SHUTTERING

COMBINED

SHUTTERING

PERMANENT FORM WORK

USING PLASTICS

Combination of main beam and sliding wedge, this new and innovative system makes set-up and stripping faster, and reduces the turn-around time of the equipment.

20x60 cm panels (weighing each max. 11 kg) and by 3 plastic beams placed upon traditional wooden trusses.

This system allows to advance the stripping operation.

This the ideal solution to build any kind of slab: bidirectional, full or lightened.

The panels can be carried by hand by a single person without the aid of a crane or of heavy lifting equipment.

Resistance to chemicals, termites ad fungi

Use of electric power not required

STAIRSWeight of throat of stairs to e supportedFormwork should e tied together to prevent sideways movement.Sideways movement is mainly because of the slope of stairsA basic principle of stair formwork is that the treads are not formed, but left open. A normal good quality concrete mix with a standard slump, (that is not too wet) will swell up slightly under vibration, but it should not pour out of the bottom in a flood.

CONCRETE STAIRS WITH HALF SPACE LANDING

A mixture of steel props and maybe steel "h" frames under the landing, and good old form ply and timber struts and braces. 

 The soffit (underneath side) ply and supports of the landing run through wider than necessary for just the concrete, to support the timbers for the upper flight of the stair.You can see that all the smaller supports are cut out of timber.The formwork will stay in place at least a week.

WIDER STAIRS SHOWING MORE STRONG BACKS

When the stairs are wider, using more than one Strongback.There are two strong backs supporting the riser timbers. There is no limit as to how many and how wide the stair can go.

SOFFIT FORMWORK FOR A FLIGHT OF CONCRETE STAIRS

STEEL STAIRSReduced construction times – achieved

because manufacture and site preparation can occur simultaneously with quick and straight forward installation, ensuring faster enclosure of the structure, minimal delay to work being carried out by other trades, and limited site congestion with no delays resulting from external weather conditions.

Substantial cost savings over conventional formwork methods.

Permanent steel handrails may be fitted immediately eliminating the need for temporary safety rails.

No topping of stairs to repair damage which occurs during construction.

The riser profile provides a ledge at the bottom for the concreter to trowel to.

they contain the fill at the center of the pour with a metal mesh box This way they could use much less concrete than if the landing and stairs had been solid.

Formwork is essential in the success of any construction project involving concrete. If designed and set-up correctly, it will function as planned. If not, any of a number of costly problems can occurReusable – panel formnon reusable – stationary form

STRIKING

MAINTENANCE

STORAGE OF FORMS

Metal beam slab formwork

The stringers and joist are replaced with aluminium forming systems or steel beams and supports are replaced with metal props.This also makes this method more systematic and reusable

Modular slab formwork

These systems consist of prefabricated timber, steel or aluminium beams and formwork modules.does not require a crane to place the formwork, speed of construction with unskilled labour, formwork modules can be removed after concrete sets leaving only beams in place prior to achieving design strength.