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Design Example The 10” TH. wall system shown in the figure below is to be checked for a service gravity load of 3 Kips/ft and a lateral load of 25 Kips,

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Presentation on theme: "Design Example The 10” TH. wall system shown in the figure below is to be checked for a service gravity load of 3 Kips/ft and a lateral load of 25 Kips,"— Presentation transcript:

1 Design Example The 10” TH. wall system shown in the figure below is to be checked for a service gravity load of 3 Kips/ft and a lateral load of 25 Kips, acting in plane to the wall. The lintel bearing is as per SBC 07. The masonry unit consist of 1500 psi solid concrete blocks with type M1 cement - sand mortar. 15 ft5 ft 10 ft 7 ft

2 Analysis (Masonry Frame Properties) 3 + 0.36 Kips /ft 25 Kips 5 ft 10 ft W1: Cross-Section Area = 10” x (15’x12) = 1800 sq.in. Inertia = 10” x (15’x12)^3 / 12 = 4860000 in 4. Weight = 0.144 x (1800 / 144) x 10” = 18 Kips Load from slab = 3 x 15’ = 45 Kips W2: Cross-Section Area = 10” x (10’x12) = 1200 sq.in. Inertia = 10” x (10’x12)^3 / 12 = 1440000 in 4. Weight = 0.144 x (1200 / 144) x 10” = 12 Kips Load from slab = 3 x 10’ = 30 Kips Beam: Cross-Section Area = 10” x (3’x12) = 360 sq.in. Inertia = 10” x (3’x12)^3 / 12 = 38880 in 4. Weight = 0.144 x (360 / 144) = 0.36 Kips / ft W1 W2 45 kip 30 kip

3 Analysis Results Axial Force (K) Shear Force (K) Bending Moment (K.ft)

4 Wall 1 Compressive stress: P/A = (45+24.7) / 1800 = 0.0387 Ksi or 38.7 psi Basic compressive stress = 0.96 MPa or 139.23 psi Slenderness ratio = H/W = (10x12)/10 = 12 k s = 0.84 Area of element = 1800/144 = 12.5 sq. ft (>2.5 sq. ft) k a = 1 Assuming height of a unit as 6 in & 10 in width: height to width ratio = 6/10 = 0.6 (<0.75) k p = 1 Allowable compressive stress = k s k a k p x Basic compressive Stress 0.84 x 1 x 1x 139.23 = 116.9 psi (OK) Flexural Stresses: P/A + My/I = 0.0387 + (199x12)(7.5x12)/4860000 = 0.0809 Ksi or 80.9 psi P/A - My/I = 0.0387 - (199x12)(7.5x12)/4860000 = -0.0035 Ksi or 3.5 psi Allowable compressive stress = 116.9 psi (OK) Allowable tensile stress = 20 psi (OK) Shear Stresses: V/A = 19.7 / 1800 = 0.0109 Ksi or 10.9 psi Allowable stress = fs = 0.1 + fd /6 = 0.1 + (38.7x0.0068)/6 = 0.1155 MPa or 16.75 psi (OK) Section 9.6.6.1 (Table 9-b) Section 9.6.6.1.1 (Table 9-b) Section 9.6.6.1.2 (Table 9-b) Section 9.6.6.1.3 (Table 9-b) Section 9.6.6.2 Section 9.6.6.3

5 Wall 2 Compressive stress: P/A = (30+22.1) / 1200 = 0.0434 Ksi or 43.4 psi Basic compressive stress = 0.96 MPa or 139.23 psi Slenderness ratio = H/W = (10x12)/10 = 12 k s = 0.84 Area of element = 1200/144 = 8.33 sq. ft (>2.5 sq. ft) k a = 1 Assuming height of a unit as 6 in & 10 in width: height to width ratio = 6/10 = 0.6 (<0.75) k p = 1 Allowable compressive stress = k s k a k p x Basic compressive Stress = 0.84 x 1 x 1x 139.23 = 116.9 psi (OK) Flexural Stresses: P/A + My/I = 0.0434 + (42.4x12)(5x12)/1440000 = 0.0646 Ksi or 64.6 psi P/A - My/I = 0.0434 - (42.4x12)(5x12)/1440000 = -0.0222 Ksi or 22.8 psi Allowable compressive stress = 116.9 psi (OK) Allowable tensile stress = 20 psi (OK) (No Tensile Stresses) Shear Stresses: V/A = 5.3 / 1200 = 0.0044 Ksi or 4.4 psi Allowable stress = fs = 0.1 + fd /6 = 0.1 + (18.4x0.0068)/6 = 0.120 MPa or 17.4 psi (OK) Section 9.6.6.1 (Table 9-b) Section 9.6.6.1.1 (Table 9-b) Section 9.6.6.1.2 (Table 9-b) Section 9.6.6.1.3 (Table 9-b) Section 9.6.6.2 Section 9.6.6.3

6 Beam Compressive stress: P/A = 5.3 / 360 = 0.0147 Ksi or 14.7 psi Basic compressive stress = 0.96 MPa or 139.23 psi Slenderness ratio = H/W = (5x12)/10 = 6 k s = 1 Area of element = 360 /144 = 2.5 sq. ft (=2.5 sq. ft) k a = 1 Assuming height of a unit as 6 in & 10 in width: height to width ratio = 6/10 = 0.6 (<0.75) k p = 1 Allowable compressive stress = ks ka kp x Basic compressive Stress =1 x 1 x 1x 139.23 = 139.23 psi (OK) Flexural Stresses: My/I = (10.6x12)(1.5x12)/38880 = 0.0588 Ksi or 58.2 psi Allowable compressive stress = 116.9 psi (OK) Allowable tensile stress = 20 psi (Not OK) (Provide reinforcement) Shear Stresses: V/A = 6.7 / 360 = 0.0186 Ksi or 18.6 psi Allowable stress = fs = 0.1 + fd /6 = 0.1 + (14.7x0.0068)/6 = 0.116 MPa or 16.82 psi (Not OK) (Inc. Section) Section 9.6.6.1 (Table 9-b) Section 9.6.6.1.1 (Table 9-b) Section 9.6.6.1.2 (Table 9-b) Section 9.6.6.1.3 (Table 9-b) Section 9.6.6.2 Section 9.6.6.3

7 Bearing Stress Check (Lintel) Bearing length = 4 in or 1/10 th of span (5x12)/10 = 6 in (Take 6 in) Bearing load = (3 + 0.36) x 5 / 2 = 8.4 Kips Bearing area = 10 x 6 = 60 sq. in P/A = 8.4/60 = 0.14 Ksi or 140 psi Allowable Compressive stress = 139.23 psi (Not OK) Bearing area with 30 ° inclination. = 10 x (6+6sin30)= 90 sq.in P/A = 8.4/90 = 0.0933 Ksi or 93.3 psi Allowable Compressive stress = 139.23 psi (OK) Section 9.6


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