# concrete pressure on formwork calculation

It is crucial to understand how to calculate concrete pressure on formwork. By accurately evaluating the load that concrete formwork systems bear, engineers can determine the right support structures and materials, ensuring construction stability and sustainability. This article provides calculations for the strength of different components like walls, beams, slabs, and walers. Through these calculations, we can optimize the design and construction processes for concrete formwork systems, thereby improving construction quality and efficiency.

## ● Importance of concrete pressure on formwork calculations

1. In the process of calculating the strength of concrete formwork systems, it is essential to first consider the strength of each concrete formwork component. Walls, beams, slabs, and walers have different load-bearing capabilities. By conducting proper strength calculations, appropriate materials and dimensions can be determined to ensure that wet concrete pressure on formwork stays within a manageable range, protecting the concrete formwork systems from deformation or damage while supporting the required loads.

2. To address the load transmission and load combination issues of different concrete formwork components, we can utilize the results of concrete formwork loads and pressure calculations to guide the operational procedures during the construction process. By applying the accurately calculated load information to practical construction, we can effectively avoid situations where the loads are excessive or unevenly distributed across components, thereby enhancing the stability and safety of concrete formwork systems.

3. The concrete pressure on formwork is another essential factor to consider. We must take into account how the load-bearing capacity of concrete formwork systems relates to factors like the height and duration of pouring concrete. By using a concrete pressure on formwork calculator to calculate the pressure distribution on concrete formwork systems, we can guide the pouring process during construction. This ensures that the concrete is poured evenly, avoiding situations where certain areas are overloaded or experience imbalanced pressures. As a result, it improves the density and quality of the concrete.

Therefore, studying and applying the calculations of concrete formwork loads and pressure can optimize concrete formwork construction and the design, ensuring their safety and reliability.

## ● concrete pressure on wall formwork

(1）Calculate the strength and deflection of the concrete formwork wall

The concrete formwork wall is a two-way panel that can bear loads from two directions. Its maximum concrete formwork dimensions are length (a) = 600mm, width (b) = 200mm, and thickness (t) = 4mm.

concrete pressure on formwork formula is as follows:

Fb=BSsb2/t2

D=ASkb4/Et3

Fb--------bending strength

B-------Checked from the table below

Ss--------Combined load design value

Sk--------combined load standard value

b--------Short side dimension of the two-way board

t--------concrete formwork thickness

A--------Check it from the table below

E-------- modulus of elasticity

D -------- deflection value

a/b | 1 | 1.2 | 1.4 | 1.6 | 1.8 | 2 | 3 | 4 |

A | 0.0138 | 0.0188 | 0.0226 | 0.0251 | 0.0268 | 0.0277 | 0.0284 | 0.0284 |

B | 0.308 | 0.383 | 0.436 | 0.468 | 0.487 | 0.497 | 0.499 | 0.5 |

a/b=3.00, Checked from the above table: A=0.0284, B=0.499
concrete pressure on formwork formula of wall:Fb=BSsb2/t2 =74.44·MPa≤fa1 = 160.00·Mpa(The strength meets the requirements)

D=ASkb4/Et3 = 0.55·mm≤b/250 = 0.8·Mm (The deflection meets the requirements)

## ● concrete pressure on formwork of beam

(2) Calculate the strength and deflection of the concrete formwork beam

The concrete formwork beam is a two-way panel that can bear loads from two directions. Its maximum concrete formwork dimensions are length (a) = 400mm, width (b) = 300mm, and thickness (t) = 4mm.

concrete pressure on formwork formula is as follows:

Fb=BSsb2/t2

D=ASkb4/Et3

Fb--------bending strength

B-------Checked from the table below

Ss--------Combined load design value

Sk--------combined load standard value

b--------Short side dimension of the two-way board

t--------concrete formwork thickness

A--------Check it from the table below

E-------- modulus of elasticity

D -------- deflection value

a/b | 1 | 1.2 | 1.4 | 1.6 | 1.8 | 2 | 3 | 4 |

A | 0.0138 | 0.0188 | 0.0226 | 0.0251 | 0.0268 | 0.0277 | 0.0284 | 0.0284 |

B | 0.308 | 0.383 | 0.436 | 0.468 | 0.487 | 0.497 | 0.499 | 0.5 |

a/b=1.33, Checked from the above table: A=0.0277, B=0.497
concrete pressure on formwork formula of beam:Fb=BSsb2/t2 = 53.32 ·MPa≤fa1 = 160.00·Mpa(The strength meets the requirements)

D=ASkb4/Et3 = 0.80·mm≤b/250 = 1.2·Mm (The deflection meets the requirements

## ● concrete pressure on formwork of slabs

Calculate the strength and deflection of concrete formwork for slabs

The concrete formwork for slabs is a two-way panel that can bear loads from two directions. Its maximum concrete formwork dimensions are length (a) = 400mm, width (b) = 400mm, and thickness (t) = 4mm.

concrete pressure on formwork formula is as follows:

Fb=BSsb2/t2

D=ASkb4/Et3

Fb--------bending strength

B-------Checked from the table below

Ss--------Combined load design value

Sk--------combined load standard value

b--------Short side dimension of the two-way board

t--------concrete formwork thickness

A--------Check it from the table below

E-------- modulus of elasticity

D -------- deflection value

a/b | 1 | 1.2 | 1.4 | 1.6 | 1.8 | 2 | 3 | 4 |

A | 0.0138 | 0.0188 | 0.0226 | 0.0251 | 0.0268 | 0.0277 | 0.0284 | 0.0284 |

B | 0.308 | 0.383 | 0.436 | 0.468 | 0.487 | 0.497 | 0.499 | 0.5 |

a/b=1.00, Checked from the above table: A=0.0138, B=0.308
concrete pressure on formwork formula of slab:Fb=BSsb2/t2 = 23.56 ·MPa≤fa1 = 160.00·Mpa(The strength meets the requirements)

D=ASkb4/Et3 = 0.48·mm≤b/250 = 1.60·Mm (The deflection meets the requirements)

## ● concrete pressure on formwork of waler

Concrete formwork waler geometry parameters:

Cross-sectional area: Al = 928mm2

Elastic modulus: E = 206,000MPa

Moment of inertia: Ip = 779,480mm4

Section modulus: Wp = 19,487mm3

Yield strength of steel (Fy): Fs = 210MPa

Flexural strength design value (steel): fsv = 150MPa

Concrete formwork waler maximum spacing: D = 800mm

Concrete formwork wall ties loaded width: B = 800mm

Uniform distributed line load design value: q = Ss · D = 47.74kN/m.

Maximum bending moment coefficient for intermediate support of a three-span continuous beam: u = 0.1.
Maximum bending moment at the support: M = u·q·B = 3.06 kN.m.

Maximum normal stress in the section: σ = M / Wp = 156.78 MPa ≤ Fs = 210.00 MPa (strength requirements satisfied).

Maximum shear force at the support: Q =q.B/2=19.10 kN

Maximum shear stress in the section: τ = Q / Al = 20.58 MPa ≤ fsv = 150.00 MPa (strength requirements satisfied).

Deflection calculation of concrete formwork waler.

Maximum deflection coefficient at the midpoint of a three-span continuous beam: u = 0.677.

Standard value of uniform distributed line load: qk = Sk.D/2=21.17 kN/m

Maximum deflection at the midspan: df= u. qk. B4/(100.E.Ip)=0.37mm ≤ B/500 =1.60mm (deflection requirements satisfied).

## ● concrete formwork loads and pressure calculations Summary

Based on a detailed study and analysis of concrete formwork loads and pressure calculations, the following conclusions can be drawn:

1. Calculating concrete pressure on formwork is a crucial factor in ensuring the safety and reliability of concrete formwork systems during construction. Properly calculating and assessing the loads borne by concrete formwork systems helps engineers determine appropriate support structures and materials, thereby ensuring construction stability and sustainability.

2. Accurate evaluation and proper control of various parameters are extremely important in the design and construction process of concrete formwork systems. A sensible design considers factors such as load distribution, the rigidity and strength of concrete formwork supports, and the height and duration of concrete formwork pour. Simultaneously, during the construction process, it is crucial to strictly follow the design requirements and maintain quality control to ensure the safe use and durability of concrete formwork systems.

3. Suggestions for further research and improvement: Despite the existing research on concrete pressure on formwork, there are still challenges and areas that can be improved. To enhance the safety and reliability of formwork systems, it is recommended to conduct further research and make improvements in the following aspects:

1) Further refine the regulations and standards for calculating concrete pressure on formwork based on real construction conditions to ensure their practicality and accuracy.

2) Carry out research on new materials and techniques to enhance the load-carrying capacity and durability of formwork in concrete.

3)Conduct more experimental studies on formwork design concrete pressure to gather additional experimental data and compare it with calculated results, thus improving the reliability of design and construction.

4) Place emphasis on training and educating construction workers on concrete formwork guidelines, strengthen quality control during the construction process and minimize the impact of human errors on concrete and formwork.

Through ongoing research and improvements, we can enhance the accuracy and reliability of concrete formwork loads and pressure calculations, thus providing dependable technical support and guidance for construction projects.

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