# Concrete Formwork Design

The **modulus of elasticity** and **strength value** of the formwork components are taken as the characteristic value. For the strength value, GK = 2.0 is accepted.

Primary Beam Interval, L

_{bk}, Secondary Beam Interval,_{Lik}, Prop Interval, L_{d}, Rod Interval, L_{b}

Primary Beam Intervals according to the selected plate thickness in slab formwork boards, beam bottom and top formwork boards, and column or shearwalls side formwork, L

_{bk},

*f _{el}*= Formwork plate bending strength [MPa]

*f _{kl}*= Formwork plate shear strength [MPa]

*GK *= Factor of safety

*p =* Pressure acting on the formwork due to fixed and live loads [MPa]

*E _{l}*= Plate Modulus of Elasticity [mm

^{2}]

*A _{l}*= Plate sectional area [mm

^{2}]

*I _{l}*= Plate section moment of inertia [mm

^{4}]

*S _{l}*= Plate section moment of strength [mm

^{3}]

*b _{l}= *Formwork plate width

For slab and column-wall formwork, *b _{l}*= 1000 mm. In the beam lower formwork plates,

*b*is taken as the width of the beam.

_{l}Secondary Beam Intervals according to primary support beam dimensions to be used in slab, beam, column and shear wall formwork, L

_{ik},

*f _{ebk}*= Primary support beam bending strength [MPa]

*f _{kbk}*= Primary support beam shear strength [MPa]

*GK *= Factor of safety

*p =* Pressure acting on the formwork due to fixed and live loads [MPa]

*E _{bk}*= Primary support beam modulus of elasticity [mm

^{2}]

*A _{bk}*= Primary support beam cross-sectional area [mm

^{2}]

*I _{bk}*= Primary support beam section moment of inertia [mm

^{4}]

*S _{bk}*= Primary support beam section moment of strength [mm

^{3}]

*L _{bk}= *Primary support beam interval

Rod Intervals to be used in column, shearwall and beam side formwork, L

_{b}

*f _{eik}*= Secondary support beam bending strength [MPa]

*f _{kik}*= Secondary support beam shear strength [MPa]

*GK *= Factor of safety

*p =* Pressure acting on the formwork due to fixed and live loads [MPa]

*E _{ik}*= Secondary support beam modulus of elasticity [mm

^{2}]

*A _{ik}*= Secondary support beam cross-sectional area [mm

^{2}]

*I _{ik}*= Secondary support beam section moment of inertia [mm

^{4}]

*S _{ik}*= Secondary support beam section moment of strength [mm

^{3}]

*L _{ik}= *Secondary support beam interval

*N _{d}= *Rod tensile capacity or prop axial pressure capacity

The props of the slab formwork will be on each secondary support beam. Prop Intervals, L

_{d}

*f _{eik}*= Secondary support beam bending strength [MPa]

*f _{kik}*= Secondary support beam shear strength [MPa]

*GK *= Factor of safety

*p _{d} =* Pressure acting on the formwork due to fixed and live loads [MPa]

*E _{ik}*= Secondary support beam modulus of elasticity [mm

^{2}]

*A _{ik}*= Secondary support beam cross-sectional area [mm

^{2}]

*I _{ik}*= Secondary support beam section moment of inertia [mm

^{4}]

*S _{ik}*= Secondary support beam section moment of strength [mm

^{3}]

*L _{ik}= *Secondary support beam interval

*N _{d}= *Rod tensile capacity or prop axial pressure capacity

The props sof the beam formwork will be on each secondary support beam.

*f _{eik}*= Secondary support beam bending strength [MPa]

*f _{kik}*= Secondary support beam shear strength [MPa]

*GK *= Factor of safety

*p _{d} =* Pressure acting on the formwork due to fixed and live loads [MPa]

*E _{ik}*= Secondary support beam modulus of elasticity [mm

^{2}]

*A _{ik}*= Secondary support beam cross-sectional area [mm

^{2}]

*I _{ik}*= Secondary support beam section moment of inertia [mm

^{4}]

*S _{ik}*= Secondary support beam section moment of strength [mm

^{3}]

*L _{ik}= *Secondary support beam interval

*N _{d}= *Rod tensile capacity or prop axial pressure capacity

In column or shearwall formwork, at least one level of support should be used to carry the wind loads calculated according to 1.2.2.

Wind effects are taken into account in the support design.

The Ƥ

_{d}value used to determine the Prop Interval, L_{d}varies according to the sequential use of the scaffoldings. The total number of stories (n) where the props are used sequentially starting from the ground story is entered as user defined.If the number of primary beam, secondary beam, rod, or prop is 2, the interval values are reduced by multiplying by 0.8.

When calculating the prop interval, the total load (nG+Q) that will affect the props is increased by 10%.

Prop interval for slabs,

Prop interval for beams,