以下介紹RC樓板撓度計算(載重:均佈載重,集中荷重or線載重請用有限元素分析程式計算)
Consider the floor system shown in Fig. a.
Estimate the deflection of the slab panel identified in part b of the figure under the follwoing conditions.
Given:
Span length along X-X direction = 30’ (9.14 m)
Span length along Y-Y direction = 26.25’ (8.0 m)
Slab thickness = 8 in (203 mm)
Ec (modulus of elasticity) = 4.287 * 106 psi ( 29,558 MPa)
Superimposed dead load = 25 psf ( 1.2 kN/m2)
Live load = 40 psf (1.9 kN/m2)
Required
Deflection of the panel at midspan for the following load combination
Superimposed dead load = 25 psf ( 1.2 kN/m2)
Live load = 40 psf (1.9 kN/m2)
Required
Deflection of the panel at midspan for the following load combination
1*DL + 1*LL
Aspect ratio γ = 30/26.25 = 1.14
Total service load q = [(20+5+40) + 150*8/12]/144 = 1.146 lb/in2 (7.9*10-3 N/mm2)
Using closed form formulas (Table 5)
(a4*q / E*h3 ) = [(30*12)4 * 1.146 / (4.287*106 * 83) = 8.77 in (222.76 mm)
For mid-panel deflection, consider case 3 from Table A
k = 0.0548
Deflection, Δ = k (a4*q / E*h3 )= 0.0548*8.77 = 0.48 in (12.20 mm)
For deflection at midpoint of column lines in X-direction, from Table 5
k = 0.0446
Deflection, Δ = k (a4*q / E*h3 )= 0.0446*8.77 = 0.39 in (9.91 mm)
撓度檢核:查表與手算之後再對照我國規範標準檢核
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