# What are load combinations?

## What are load combinations?

A load combination results when more than one load type acts on the structure. Building codes usually specify a variety of load combinations together with load factors (weightings) for each load type in order to ensure the safety of the structure under different maximum expected loading scenarios.

## Which load combination is correct?

Explanation: For limit state of strength, the load combination is 1.5(DL+LL), for limit state of serviceability, the load combination is 1.0(DL+LL), where DL=Dead load, LL=imposed load.

**What are the load combinations of ASD and LRFD?**

ASD

LRFD-LC1 | 1.4(D+F) |
---|---|

LRFD-LC2a | 1.2(D + F + T) + 1.6(L + H) + 0.5Lr |

LRFD-LC2b | 1.2(D + F + T) + 1.6(L + H) + 0.5S |

LRFD-LC2c | 1.2(D + F + T) + 1.6(L + H) + 0.5R |

LRFD-LC2i | 1.2(D + F + T) + 1.6(L + H) + 0.2Di + 0.5S |

**What is the most common load combination?**

These are also known as ultimate load combinations:

- 1.4D.
- 1.2D + 1.6L + 0.5(Lr or S or R)
- 1.2D + 1.6(Lr or S or R) + (L or 0.5W)
- 1.2D + 1.0W + L+0.5(Lr or S or R)
- 1.2D + 1.0E + L +0.2S.
- 0.9D + 1.0W.
- 0.9D + 1.0E.

### Is 800 a combination load?

a) Dead load + imposed load, b) Dead load + imposed load + wind or earthquake load, c) Dead load + wind or earthquake load, and d) Dead load+ erection load. The effect of wind load and earthquake loads shall not be considered to act simultaneously. The load combinations are outlined in detail in Cl. 3.5 of IS 800:2007.

### Is 1893 a load combination?

For IS 1893:2016, the maximum load combination factor is 1.5 and for NBC 105:1994 the maximum load combination factor is 1.3.

**What are ASD load combinations?**

It focuses on the requirements for general structural design, as well as providing a means for determining loads (dead, live, soil, flood, snow, rain, ice, earthquake, wind) and their combinations. Allowable Strength Design (ASD) involves eight basic load combination equations.

**Is earthquake load a code?**

Today, the Bureau of Indian Standards (BIS) has the following seismic codes: IS 1893 (Part I), 2002, Indian Standard Criteria for Earthquake Resistant Design of Structures (5th Revision) IS 4326, 1993, Indian Standard Code of Practice for Earthquake Resistant Design and Construction of Buildings (2nd Revision) IS 13827 …

#### How many load combinations are there in LRFD?

seven

Load and Resistance Factor Design (LRFD) involves seven basic load combination equations.

#### What is meant by load combination?

Generally, load combination is composed of individual loads, i.e. dead load superimposed dead loads and live loads that are combined together to come up for a strength design and allowable stress design.

**How to determine the appropriate design load combinations for a project?**

After establishing the design loads of the proposed project, the next thing to consider is to determine the appropriate design load combinations. Generally, load combination is composed of individual loads, i.e. dead load superimposed dead loads and live loads that are combined together to come up for a strength design and allowable stress design.

**What are the 5 load combinations?**

These are also known as ultimate load combinations: 1 1.4D 2 1.2D + 1.6L + 0.5 (Lr or S or R) 3 1.2D + 1.6 (Lr or S or R) + (L or 0.5W) 4 1.2D + 1.0W + L+0.5 (Lr or S or R) 5 1.2D + 1.0E + L +0.2S 6 0.9D + 1.0W 7 0.9D + 1.0E

## How do we select the safety factors for load combinations?

Depending on the effect of loading on the structure we select the safety factors for load combinations. The following table in BS 8110 shows the load factors for load combinations. For example, we can create load combinations as follows. When earth pressure and dead load is considered, we create following load combination