Load combination as per IS 456 | Load combination for foundation | Load combination for structural design
Load combination as per IS 456 | Load combination for foundation | Load combination for structural design
Load combination
The load combinations are mainly used in structural design of all building. The combination of two or more loads with the suitable factor of safety namely 1.5, 1.2 or 0.9 is called a load combination.
As per the gravity loads & lateral loads the load combinations are varies. These combinations will helps to minimise the maximum reinforcement values & maximum bending moments for the particular structures. The below-specified loads are considered in the loads combination as per the IS 456-2000 code and IS 1893-2016 code.
LOAD IN BUILDING
- Dead load
- Live load
- Seismic load
- Wind load
Load Combinations for RCC Structures
Combinations as per IS 456:
For Limit State of Collapse:
For Limit State of Serviceability:
For Foundation Design:
Important Note:
- In case of Earth quake(Seismic) load SBC can be increased by 25%
- In case of Wind load SBC can be increased by 25% by following codal provisions
The load combination for gravity load & lateral load (Dead load + live load + wind load or seismic load) may be neglected in design and first load combination(gravity load) i.e. Dead load + Live Load shall be compared with safe bearing capacity due to shear criteria and allowable bearing capacity due settlement criteria where wind or seismic load is less than 25 % of that due to dead &live loads. Where wind or seismic load is more than 25 % of that due to dead and live loads, foundations may be so proportioned that the pressure due to combination of load (dead + live + wind load) does not exceed the safe bearing capacity by more than 25 % When seismic forces are considered, the safe bearing capacity shall be increased as specified in IS: 1893-1984.
Net safe SBC for (DL+LL +EQ) comb = SBC*(A)
A = 150% for footing with tie beams on Rock and hard soil
A = 125% for footing with tie beams on Medium soil /or soft soil
A = 150% for footing without tie beams on Rock and hard soil
A = 125% for footing without tie beams on Medium soil
A = 0.00% for footing without tie beams on soft soil
.YESTERDAY JOBS
INDIAN JOBS
For both Earthquake(Seismic) & Wind Loads
Load Cases
- Earthquake load along +ve x direction
- Earthquake load along -ve x direction
- Earthquake load along +ve z direction
- Earthquake load along -ve z direction
- Wind load along +ve x direction
- Wind load along -ve x direction
- Wind load along +ve x direction
- Wind load along -ve x direction
- Floor Load (Dead Load) - FLDL
- Dead Load – DL
- Floor Load (Live Load) - FLLL
- Live Load – LL
Combination of loads
1 Dead load, Live load 1.5 (DL+LL)
2 Dead load, Live load and Seismic load 1.2 (DL+LL+EQx)
3 Dead load, Live load and Seismic load 1.2 (DL+LL-EQx)
4 Dead load, Live load and Seismic load 1.2 (DL+LL+EQy)
5 Dead load, Live load and Seismic load 1.2 (DL+LL-EQy)
6 Dead load, Seismic load 1.5 (DL+EQx)
7 Dead load, Seismic load 1.5 (DL-EQx)
8 Dead load, Seismic load 1.5 (DL+EQy)
9 Dead load, Seismic load 1.5 (DL-EQy)
10 Dead load, Live load and wind load 1.2 (DL+LL+WLx)
11 Dead load, Live load and wind load 1.2 (DL+LL-WLx)
12 Dead load, Live load and wind load 1.2 (DL+LL+WLy)
13 Dead load, Live load and wind load 1.2 (DL+LL-WLy)
14 Dead load, wind load 1.5 (DL+WLx)
15 Dead load, wind load 1.5 (DL-WLx)
16 Dead load, wind load 1.5 (DL+WLy)
17 Dead load, wind load 1.5 (DL-WLy)
18 Dead load, Seismic load 0.9DL+1.5EQx
19 Dead load, Seismic load 0.9DL-1.5EQx
20 Dead load, Seismic load 0.9DL+1.5EQy
21 Dead load, Seismic load 0.9DL-1.5EQy
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