Building load analysis & RCC member design

IS 875 (Part 1/2/3) · IS 1893 (Part 1):2016 seismic · IS 456:2000 limit state design · no frame analysis

Project—

Concrete / steel—

Storeys—

Seismic zone—

Checks passing—

1 Project & materials

Project name

City (sets basic wind speed)

Storeys above ground

Floor to floor height

Plan length L

Plan width B

Grade of concrete, fck

Grade of steel, fy

Grade of links, fy(s)

Unit weight of RCC

Safe bearing capacity

2 Member sizes & cover

Slab thickness

Beam width

Beam depth

Column size along X

Column size along Y

Cover — slab

Cover — beam

Cover — column

Cover — footing

3 Dead load — IS 875 Part 1

Floor finish thickness (mm)

Unit weight of finish

Ceiling plaster thickness (mm)

Unit weight of plaster

Services allowance (kN/m2)

External wall thickness (mm)

Internal wall thickness (mm)

Unit weight of masonry

Wall plaster, both faces (mm)

Opening reduction factor

Roof waterproofing (kN/m2)

4 Live load — IS 875 Part 2

Occupancy

Corridor / balcony LL

Live load is reduced for columns by 10% per floor carried, capped at 50% (Cl. 3.2). The reduction is not permitted where the live load exceeds 5 kN/m².

5 Wind load — IS 875 Part 3:2015

Risk coefficient k1

Terrain category

Topography factor k3

Cyclone factor k4

Directionality Kd

Area averaging Ka

Combination Kc

Force coefficient Cf

6 Seismic load — IS 1893 (Part 1):2016

Seismic zone

Importance factor I

Response reduction factor R

Site / soil type

Building type for period Ta

Columns per floor (nos)

Beam length per floor (m)

External wall length per floor (m)

Internal wall length per floor (m)

Imposed load in the seismic weight follows Cl. 7.3.1 — 25 % when LL ≤ 3 kN/m², 50 % when LL > 3 kN/m². Imposed load on the roof is not included (Cl. 7.3.2). Equivalent static method, Cl. 7.6.

7 Slab

Shorter span lx (m)

Longer span ly (m)

Panel case — IS 456 Table 26

Bar diameter

Bar spacing

Basic span/depth ratio

Deflection factor kt (Fig. 4)

8 Beam

Effective span (m)

Support condition

Main bar diameter

Number of bars

Stirrup diameter

Stirrup legs

Stirrup spacing

9 Column

Effective length factor k

Tributary floor area (m2)

Beam load per floor (kN)

Wall load per floor (kN)

Bar diameter

Number of bars

Tie pitch

10 Footing

Self weight allowance (%)

Footing length L (m)

Footing width B (m)

Overall depth (mm)

Bar diameter

Bar spacing

Loads

Seismic load — IS 1893 (Part 1):2016

Storey forces are distributed as Qi = VB · Wi hi² / Σ Wj hj² (Cl. 7.6.3). Storey drift must be limited to 0.004 times the storey height (Cl. 7.11.1); that check needs a frame analysis and is not performed here.

Slab design

Beam design

Column design

Footing design

Summary schedule

The member design above uses the gravity combination 1.5(DL + LL) only. The seismic base shear and storey forces are computed by the equivalent static method, but distributing them into individual beams and columns needs a frame analysis, which this tool does not perform. Where the seismic combination governs, redesign the members for the forces from that analysis. Every result must be checked and sealed by a qualified structural engineer before construction.