Week 6 Challenge

Aim: To understand the structural system of Industrial Structure namely

• Lateral Force Resisting Systems
• Vertical Force Resisting Systems
• Flooring Systems

Introduction:

Structural system, in building construction, the particular method of assembling and constructing structural elements of a building so that they support and transmit applied loads safely to the ground without exceeding the allowable stresses in the members.

Procedure in detail:

1. Chequered Plate design

Design a chequered plate to carry a uniformly distributed Factored live load of 15 kN/m2. Consider the plate is spanned with dimension of 1200 mm x 5000 mm with all edges fixed. (Refer Roarks chart table 11.4)

Solution:

Factored live load = 15 kN/m²

Self-weight = 7850kg/m³ x 10/1000mm = 0.0785kN/m² which is negligible

Long span = 5000mm

Shorter span = 1200mm

Assume Plate thickness t = 10mm

Condition: All edges are fixed

Yield stress = 250 MPa

Allowable deflection

As per table 11.4

8^th point for all sides fixed

a/b = 5000/1200 = 4.167

B1 = 0.5

B2 = 0.25

(4.167>2 / α value taken)

α = 0.0284

Sigma(max)= -B1q²b² / t² (center)

= -(0.5x15x10³Nx1200² mm²)/ 10⁶ mm²x 10² mm² = -108 N/mm² < 250 N/mm²

Hence Safe

Sigma(centre)= B2qb² / t²

= (0.25x15x10³Nx1200² mm²)/ 10⁶ mm²x 10² mm² = 54 N/mm²

Max. Deflection = αqb⁴/Et³

= (0.0284 x 15 x 10³ N x 1200⁴) / (2x10⁵ N/mm² x 10⁶ mm²x 10³ = 4.42mm

Allowable Deflection = Thickness/2 = 10/2 = 5mm

Hence Safe

2. Design of Decking slab.

Design thickness of RC slab required to carry Dead load of 5 kN/m2 & Live Load of 8 kN/m2 for a mezzanine floor in an Industrial structure with plan as shown below. Provide optimum spacing of the secondary beam and also choose the decking sheet profile to be used. Neglect the composite action of decking sheet and RC slab. Decking sheet is provided only for formwork purpose.

DL = 5kN/m²

LL = 8kN/m²

To identify the spacing of beam

Assume 100mm thick RC Slab

Therefore, 25x0.1 = 25kN/m²

Total load = [(2.5+5)+8]x1.5 = 23.25kN/m²

From Manufactures Standard provided

Choose Provide PLL75/230

Thickness 1.25mm

Span – 1.5m

w_t = 14.90 kg/m²

Allowable load = 2993 kg/m² = 29.36 kN/m²

Since, it will span for 2 to 3 supports

0.8 x 29.30 = 23.48 kN/m²

Including w_t = 14.90 kg/m² = 0.14 kN/m²

23.25 + 0.149 = 23.399 kN/m² < 23.48 kN/m²

Hence Safe

Choose spacing thickness & profile such that

Spacing of beam and weight of sheet are chosen for optimized station

Therefore, Now placing beams

Max span of slab is (1.5x8m)

Quick check on slab thickness

One way slab (RC)

Ly/Lx = 8/1.5 = 5.33 > 2 (1 way)

Assumed depth of slab

Span/d = 25

d = 1500/25

Effective depth = mm

Effective depth = 60+75 = 97.5mm

Therefore, choose effective depth as 100mm

3. Lateral Load resisting system & Gravity Load resisting system

Draw the load path and identify the axial force type in different type of bracing system below to resist horizontal shear & gravity load. Also state the type of bracing system