What is Load Combination | Load Combination as per IS 456

In this article, We explain the various load combinations are used in design of RCC Structure as well as Steel Structure. Also share the load combinations for Limit state of strength as well as limit state of serviceability.

So Read the article till the end, and if you get any knowledge from this article, please share with your friends. Let’s Start.

What is Load Combination

Load Combination is define as a set of various loading condition that are acting together in structure which is used to ensure the required safety and economy in the design of a structure.

While, A load combination causing critical condition in structure such as maximum deformation and stress etc. known as a Critical Load Combination.

It is a set of such load cases which is likely to act together on structure such as dead load, live load and wind load or dead load, live load and earthquake load etc.

It is very high chance to not occurrence of earthquake and wind load on building simultaneously. That’s why in load combination, wind load and earthquake loads are not in same sets.

Load Combination as per IS 456 – 2015

Load combination as per is 456 for grouped in two categories, 1. Limit State of Collapse, 2. Limit State of Serviceability.

Also Read: Working Stress Method Vs Limit State Method of design

Load Combination as per  IS 456

1. Load Combination for Limit State of Collapse

Limit State design Combination

  • 1.5 (DL+LL)

Earthquake Load combinations for Design

  • 1.5 (DL+EQX)
  • 1.5 (DL-EQX)
  • 1.5 (DL+EQZ)
  • 1.5 (DL-EQZ)
  • 1.2(DL+LL+EQX)
  • 1.2(DL+LL-EQX)
  • 1.2(DL+LL+EQZ)
  • 1.2(DL+LL-EQZ)
  • 0.9DL+1.5EQX
  • 0.9DL-1.5EQX
  • 0.9DL+1.5EQZ
  • 0.9DL-1.5EQZ

Wind Load Combination for design

  • 1.5(DL+WLX)
  • 1.5(DL-WLX)
  • 1.5(DL+WLZ)
  • 1.5(DL-WLZ)
  • 1.2(DL+LL+WLX)
  • 1.2(DL+LL-WLX)
  • 1.2(DL+LL+WLZ)
  • 1.2(DL+LL-WLZ)
  • 0.9DL+1.5WLX
  • 0.9DL-1.5WLX
  • 0.9DL+1.5WLZ
  • 0.9DL-1.5WLZ

Do you know: How to Calculate different Types of load in building

2. Load Combination for Limit State of Serviceability

Limit state Serviceability Combination

  • DL+LL

Earthquake Serviceability Combination

  • DL+LL+EQX
  • DL+LL-EQX
  • DL+LL+EQZ
  • DL+LL-EQ
  • DL+EQX
  • DL-EQX
  • DL+EQZ
  • DL-EQZ

Wind Load Serviceability Combination

  • DL+WLX
  • DL-WLX
  • DL+WLZ
  • DL-WLZ
  • DL+LL+WLX
  • DL+LL-WLX
  • DL+LL+WLZ
  • DL+LL-WLZ

3. Load Combination with Temperature Load

Design Combination With Temperature Load

  • 1.5(DL+LL+TL)

Earthquake Load combinations with Temperature Load

  • 1.0(DL + EQX + TL)
  • 1.0(DL – EQX + TL)
  • 1.0(DL + EQZ + TL)
  • 1.0(DL – EQZ + TL)
  • 1.0(DL + LL + EQX + TL)
  • 1.0(DL + LL – EQX + TL)
  • 1.0(DL + LL + EQZ + TL)
  • 1.0(DL + LL – EQZ + TL)

Wind Load Combination with Temperature load

  • 1.0(DL + WLX + TL)
  • 1.0(DL – WLX + TL)
  • 1.0(DL + WLZ + TL)
  • 1.0(DL – WLZ + TL)
  • 1.0(DL + LL + WLX + TL)
  • 1.0(DL + LL – WLX + TL)
  • 1.0(DL + LL + WLZ + TL)
  • 1.0(DL + LL – WLZ + TL)

Do you Know: Earthquake Proof Masonry Construction Aspects

Load Combinations As Per IS 1893 -2016

1. Load Combinations for Orthogonal Structural Element

When Lateral load resisting element are oriented along two mutually orthogonal horizontal directions, structure shall be designed for effects due to full design earthquake load in one horizontal direction at a time, and not in both directions simultaneously. That means the load combination are used as per IS456 criteria which is listed above.

2. Load Combinations for Non Orthogonal Structural Element

When lateral load resisting elements are not oriented along mutually orthogonal directions, Structure shall be designed for the simultaneous effect due to full design earthquake load in one horizontal direction plus 30% of design earthquake load along the other horizontal direction. Thus structure should be designed for the following sets of combinations of earthquake effects.

load combination for design of non orthogonal structural member

For above mentioned criteria, sets of load combination are listed below.

Earthquake load combinations for design

  • 1.5(DL+EQX+0.3EQZ)
  • 1.5(DL+EQX-0.3EQZ)
  • 1.5(DL-EQX-0.3EQZ)
  • 1.5(DL-EQX+0.3EQZ)
  • 1.5(DL+EQZ+0.3EQX)
  • 1.5(DL+EQZ-0.3EQX)
  • 1.5(DL-EQZ-0.3EQX)
  • 1.5(DL-EQZ+0.3EQX)
  • 1.2(DL+LL+EQX+0.3EQZ)
  • 1.2(DL+LL+EQX-0.3EQZ)
  • 1.2(DL+LL-EQX-0.3EQZ)
  • 1.2(DL+LL-EQX+0.3EQZ)
  • 1.2(DL+LL+EQZ+0.3EQX)
  • 1.2(DL+LL+EQZ-0.3EQX)
  • 1.2(DL+LL-EQZ-0.3EQX)
  • 1.2(DL+LL-EQZ+0.3EQX)
  • 0.9DL+1.5(EQX+0.3EQZ)
  • 0.9DL+1.5(EQX-0.3EQZ)
  • 0.9DL-1.5(EQX+0.3EQZ)
  • 0.9DL-1.5(EQX-0.3EQZ)
  • 0.9DL+1.5(EQZ+0.3EQX)
  • 0.9DL+1.5(EQZ-0.3EQX)
  • 0.9DL-1.5(EQZ+0.3EQX)
  • 0.9DL-1.5(EQZ-0.3EQX)

Also Check: How to Calculate Expansion Joint in Building

Earthquake Load Combinations for Serviceability checks

  • DL+LL+EQX+0.3EQZ
  • DL+LL+EQX-0.3EQZ
  • DL+LL-EQX+0.3EQZ
  • DL+LL-EQX-0.3EQZ
  • DL+LL+EQZ+0.3EQX
  • DL+LL+EQZ-0.3EQX
  • DL+LL-EQZ+0.3EQX
  • DL+LL-EQZ-0.3EQX
  • DL+EQX+0.3EQZ
  • DL+EQX-0.3EQZ
  • DL-EQX+0.3EQZ
  • DL-EQX-0.3EQZ
  • DL+EQZ+0.3EQX
  • DL+EQZ-0.3EQX
  • DL-EQZ+0.3EQX
  • DL-EQZ-0.3EQX

3. Three Directional Earthquake Load Combination

Indian Standard IS 1893 -2016 Suggested that if your structure followed any conditions which are listed below, It is necessary to consider vertical earthquake shaking in your structure design.

  • Structure is located in Seismic Zone IV or V
  • Structure has vertical or plan irregularities.
  • Structure is rested on soft soil.
  • Bridges.
  • Structure has long spans.
  • Structure has large horizontal overhangs of structural members or sub-systems.

The all Three dimensional load combinations are listed below.

three dimensional earthquake load combinations

Also Read: Ductile Detailing of Beam as per IS 13920-2016

Three dimensional earthquake load combination for design

  • 1.5(DL+EQX+0.3EQZ+0.3EQY)
  • 1.5(DL+EQX+0.3EQZ-0.3EQY)
  • 1.5(DL+EQX-0.3EQZ+0.3EQY)
  • 1.5(DL+EQX-0.3EQZ-0.3EQY)
  • 1.5(DL-EQX-0.3EQZ-0.3EQY)
  • 1.5(DL-EQX-0.3EQZ+0.3EQY)
  • 1.5(DL-EQX+0.3EQZ-0.3EQY)
  • 1.5(DL-EQX+0.3EQZ+0.3EQY)
  • 1.5(DL+EQZ+0.3EQX+0.3EQY)
  • 1.5(DL+EQZ+0.3EQX-0.3EQY)
  • 1.5(DL+EQZ-0.3EQX+0.3EQY)
  • 1.5(DL+EQZ-0.3EQX-0.3EQY)
  • 1.5(DL-EQZ-0.3EQX-0.3EQY)
  • 1.5(DL-EQZ-0.3EQX+0.3EQY)
  • 1.5(DL-EQZ+0.3EQX-0.3EQY)
  • 1.5(DL-EQZ+0.3EQX+0.3EQY)
  • 1.2(DL+LL+EQX+0.3EQZ+0.3EQY)
  • 1.2(DL+LL+EQX+0.3EQZ-0.3EQY)
  • 1.2(DL+LL+EQX-0.3EQZ+0.3EQY)
  • 1.2(DL+LL+EQX-0.3EQZ-0.3EQY)
  • 1.2(DL+LL-EQX-0.3EQZ-0.3EQY)
  • 1.2(DL+LL-EQX-0.3EQZ+0.3EQY)
  • 1.2(DL+LL-EQX+0.3EQZ-0.3EQY)
  • 1.2(DL+LL-EQX+0.3EQZ+0.3EQY)
  • 1.2(DL+LL+EQZ+0.3EQX+0.3EQY)
  • 1.2(DL+LL+EQZ+0.3EQX-0.3EQY)
  • 1.2(DL+LL+EQZ-0.3EQX+0.3EQY)
  • 1.2(DL+LL+EQZ-0.3EQX-0.3EQY)
  • 1.2(DL+LL-EQZ-0.3EQX-0.3EQY)
  • 1.2(DL+LL-EQZ-0.3EQX+0.3EQY)
  • 1.2(DL+LL-EQZ+0.3EQX-0.3EQY)
  • 1.2(DL+LL-EQZ+0.3EQX+0.3EQY)
  • 0.9DL+1.5(EQX+0.3EQZ+0.3EQY)
  • 0.9DL+1.5(EQX+0.3EQZ+0.3EQY)
  • 0.9DL+1.5(EQX-0.3EQZ+0.3EQY)
  • 0.9DL+1.5(EQX-0.3EQZ-0.3EQY)
  • 0.9DL-1.5(EQX+0.3EQZ+0.3EQY)
  • 0.9DL-1.5(EQX+0.3EQZ+0.3EQY)
  • 0.9DL-1.5(EQX-0.3EQZ+0.3EQY)
  • 0.9DL-1.5(EQX-0.3EQZ-0.3EQY)
  • 0.9DL+1.5(EQZ+0.3EQX+0.3EQY)
  • 0.9DL+1.5(EQZ+0.3EQX+0.3EQY)
  • 0.9DL+1.5(EQZ-0.3EQX+0.3EQY)
  • 0.9DL+1.5(EQZ-0.3EQX-0.3EQY)
  • 0.9DL-1.5(EQZ+0.3EQX+0.3EQY)
  • 0.9DL-1.5(EQZ+0.3EQX+0.3EQY)
  • 0.9DL-1.5(EQZ-0.3EQX+0.3EQY)
  • 0.9DL-1.5(EQZ-0.3EQX-0.3EQY)

Also Check: 4 Best Books for Reinforced Concrete Design

Three dimensional earthquake load combination for Serviceability check

  • DL+LL+EQX+0.3EQZ+0.3EQY
  • DL+LL+EQX+0.3EQZ-0.3EQY
  • DL+LL+EQX-0.3EQZ+0.3EQY
  • DL+LL+EQX-0.3EQZ-0.3EQY
  • DL+LL-EQX-0.3EQZ-0.3EQY
  • DL+LL-EQX-0.3EQZ+0.3EQY
  • DL+LL-EQX+0.3EQZ-0.3EQY
  • DL+LL-EQX+0.3EQZ+0.3EQY
  • DL+LL+EQZ+0.3EQX+0.3EQY
  • DL+LL+EQZ+0.3EQX-0.3EQY
  • DL+LL+EQZ-0.3EQX+0.3EQY
  • DL+LL+EQZ-0.3EQX-0.3EQY
  • DL+LL-EQZ-0.3EQX-0.3EQY
  • DL+LL-EQZ-0.3EQX+0.3EQY
  • DL+LL-EQZ+0.3EQX-0.3EQY
  • DL+LL-EQZ+0.3EQX+0.3EQY
  • DL+EQX+0.3EQZ+0.3EQY
  • DL+EQX+0.3EQZ-0.3EQY
  • DL+EQX-0.3EQZ+0.3EQY
  • DL+EQX-0.3EQZ-0.3EQY
  • DL-EQX-0.3EQZ-0.3EQY
  • DL-EQX-0.3EQZ+0.3EQY
  • DL-EQX+0.3EQZ-0.3EQY
  • DL-EQX+0.3EQZ+0.3EQY
  • DL+EQZ+0.3EQX+0.3EQY
  • DL+EQZ+0.3EQX-0.3EQY
  • DL+EQZ-0.3EQX+0.3EQY
  • DL+EQZ-0.3EQX-0.3EQY
  • DL-EQZ-0.3EQX-0.3EQY
  • DL-EQZ-0.3EQX+0.3EQY
  • DL-EQZ+0.3EQX-0.3EQY
  • DL-EQZ+0.3EQX+0.3EQY

Do you Know: Criteria for Arrangement of Ties in Column

Load Combination Quiz

Structural Load

Load Combination As per IS 456

This Quiz includes the question and answer related to Load Combination as per IS 456 & IS 1893

1 / 6

DL+LL+WL Combination for Limit State of Serviceability is

2 / 6

Earthquake Load Combination for Non Orthogonal Structures?

Where,

  • EQX and EQY is Horizonal Earthquake Force
  • EQZ is Vertical Earthquake Force

3 / 6

DL+WL Combination for Limit State of Collapse is

4 / 6

DL+IL+WL Combination for Limit State of Collapse is

5 / 6

1.5 (DL+LL) is a load combination of

6 / 6

Three Dimensional Earthquake Load Combination is Used in which cases?

Your score is

The average score is 75%

0%

What are the load combinations for deflection check?

The Serviceability load combinations are used to check deflection of any structure. all serviceability load combination are listed above.

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