3.2 Basic formula for structural calculation of bamboo plywood:
The structural calculation of bamboo plywood is mainly based on the Code for Design of Wood Structures, and the formula for checking the bearing capacity of flexural members is:
Δ m = m/w ≤ FM (4), where: Δ m- calculated bending stress of members (N/mm2), m-calculated bending moment of plate surface according to load (Nmm), w- static sectional resistance moment of members (mm), FM- designed bending strength of wood (N/mm2),
Deflection calculation formula: ω≤[ω](5)ω- calculated deflection value, [ω]-allowable deflection value, and 2mm is recommended.
4. Calculation example
At present, the widely used 12mm bamboo plywood is used for calculation to determine the reasonable spacing of small supporting beams. Assume that the static bending strength FK=60N/mm2 provided by the manufacturer, the partial coefficient of material properties γF=4.0, the bending design strength FD= 15N/mm2, and the elastic modulus E=5000N/mm2.
4. 1 horizontal template calculation (small stare blankly spacing L=300 mm)
Calculation of (1) bearing capacity
First, calculate the load (concrete slab thickness is 120mm) and width is1m.. Load calculation is shown in Table 3, Load Calculation Table.
Table 3
Load item load standard value (KN/ m2) load score
Component coefficient design load value (KN/ m)
1. Self-weight of formwork 0 1.2 0
2. Fresh concrete
Dead weight 24*0. 12 1.2 3.456
3. Self-weight of reinforcement 1.0 1.2 1.2
4. Construction personnel and
Equipment load 2.5 1.4 3.5
Total 9.356
The bending moment between fulcrums is m = ql2/8 = 9.356 * 0.3 * 300/8 =105.255kmm, calculated as the intermediate beam.
Jing sectional resistance moment:
w = bh2/6 = 1000 * 122/6 = 24000 mm3
Maximum stress of section:
δM = M/W = 105.255 * 1000/24000
=4.38 N/mm2？ FD= 15 N/mm2 (qualified)
(2) Deformation calculation:
When calculating the deflection, the load is 1, 2,3.
ω=5ql4/384*EJ
=5*4.656*3004/384*5000* 144* 1000
=0.682 mm？ [ω] =2mm. (Qualified