Project 2

Design Basis Report for Warehouse Building:

Project Name: Warehouse Building in Chennai Location: Chennai, India Design Standards: IS800:2007, IS1893 and IS 875

General Project Description: The warehouse building is a single-story steel structure with dimensions of 30m x 50m and an eave height of 9m. The roof slope is 1 in 12, and the bay spacing is 6m. The soil type is medium, and the safe bearing capacity is 200 kN/m2. The structure will be designed to resist gravity loads, wind loads and seismic loads as per IS1893.

Design Criteria:

1. Design Load Combinations: The following load combinations will be considered for the design of the structure as per IS875: a) 1.5(DL + LL) b) 1.2(DL + LL) + 1.5(EQL) c) 1.2(DL + LL) + 1.5(WL) d) 0.9(DL + LL + EQL) + 1.5(WL)

where, DL = Dead Load LL = Live Load EQL = Earthquake Load WL = Wind Load

2. Design Loads: The design loads for the warehouse building are as follows: a) Dead Load: i) Roof Sheeting: 0.05 kN/m2 ii) Purlins and Girts: 0.075 kN/m2 iii) Columns: 1.2 kN/m2 iv) Bracings: 0.05 kN/m2 v) Crane Load: 0.25 kN/m2 Total Dead Load = 1.6 kN/m2

   b) Live Load: 2.5 kN/m2 c) Wind Load: i) Basic Wind Speed: 47 m/s (As per IS 875) ii) Importance Factor: 1.0 iii) Terrain Category: 2 iv) Shielding Factor: 0.85 v) Design Wind Speed: 31.96 m/s vi) Wind Pressure Coefficient: 0.6 Wind Load = 0.115 kN/m2 d) Earthquake Load: i) Zone Factor: 0.16 (As per IS 1893) ii) Importance Factor: 1.0 iii) Soil Type Factor: 2.5 (As per IS 1893) iv) Response Reduction Factor: 5.0 (As per IS 1893) Earthquake Load = 0.039 kN/m2

3. Structural Elements and Design Parameters: The structural elements and their design parameters for the warehouse building are as follows: a) Columns: i) Material: ISMB 400 ii) Section Properties: Area = 4170 mm2, Ixx = 478 x 104 mm4, Iyy = 113 x 104 mm4 iii) Axial Load: 15 kN iv) Bending Moment: 116.1 kNm v) Check for Lateral Torsional Buckling (LTB) and Slenderness Ratio (λ) b) Rafters: i) Material: ISMB 400 ii) Section Properties: Area = 4170 mm2, Ixx = 478 x 104 mm4, Iyy = 113 x 104 mm4 iii) Span: 6m iv) Check for Maximum Bending Moment

To design a simply supported gantry girder to carry electric overhead travelling crane, we need to follow the below steps:

Step 1: Determine the maximum bending moment due to the weight of the crane and other loads

The maximum bending moment due to the weight of the crane and other loads can be calculated as follows:

Mmax = (WL/8) × (4L/3 + 2a)

Where, W = Total weight of crane = 250 kN L = Span of crane girder = 9 m a = Minimum hook approach = 1.0 m

Mmax = (250 × 9 / 8) × (4 × 9 / 3 + 2 × 1.0) = 527.34 kN-m

Step 2: Determine the self-weight of the gantry girder

The self-weight of the gantry girder can be calculated using the following formula:

W = (A × L × γ)

Where, A = Cross-sectional area of the gantry girder L = Span of the gantry girder = 7 m γ = Unit weight of the material

Assuming the gantry girder is made of ISMB450, the cross-sectional area can be obtained from the standard table. The unit weight of ISMB450 is 60 kg/m.

A = 1989 mm2

W = (1989 × 7 × 60) / 1000 = 837.18 kN

Step 3: Determine the maximum shear force due to the weight of the crane and other loads

The maximum shear force due to the weight of the crane and other loads can be calculated as follows:

Vmax = (W/2) + (WL/4)

Where, W = Total weight of crane = 250 kN L = Span of crane girder = 9 m

Vmax = (250/2) + (250 × 9/4) = 536.25 kN

Step 4: Check for deflection

The deflection of the gantry girder should be within the permissible limit. As per IS 800:2007, the maximum permissible deflection for the gantry girder is L/800.

Maximum permissible deflection = 7 / 800 = 0.00875 m

Step 5: Design the gantry girder

Based on the maximum bending moment and maximum shear force, we can design the gantry girder. We can use the standard table of ISMB section to select the appropriate section.

Assuming the gantry girder is made of ISMB600, the section modulus can be obtained from the standard table.

Z = 34348 mm3

The required section modulus can be calculated as follows:

Zreq = Mmax / (σb × d)

Where, σb = Allowable bending stress = fy / γm = 250 / 1.10 = 227.27 N/mm2 d = Depth of the section = 600 mm

Zreq = (527.34 × 106) / (227.27 × 600) = 12,147.83 mm3

As Z > Zreq, the section is safe in bending.

Similarly, the required web area for the shear force can be calculated as follows:

Awreq = Vmax / (τw × d)

Where, τw = Allowable shear stress = 0.43 × fy / γm = 93.07 N/mm2

Awreq = (536.25 × 103) / (93.07 × 600) = 9.17 mm2

Assuming the web thickness as 10 mm,