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(OP)
Clause 5.3.2 of ACI 318-14 states that: "the effect of one or more loads not acting simultaneously must be investigated".

What does that mean? Does this mean we need to investigate Dead Load Alone, Live Load Alone, EQ Load Alone and Wind Load Alone? I thought we need to use the Load Combinations in Section 5.3.1 of ACI 318-14.

Thanks.

### RE: ACI 318 (Load Combinations)

I think it is meant to consider pattern load, or uneven live load, that might lead to critical effects, such as stress reversal.

### RE: ACI 318 (Load Combinations)

(OP)
Thank you. Yes, it can be explained this way but still not clear for me.

Like for example, in the following load combo:
1.2D + 1.0E + 1.0L + 0.2S
Do we need to derive the following load combos from it (considering that dead load must always be applied)?
1.2D + 1.0E
1.2D + 1.0E + 1.0L
1.2D + 1.0E + 0.2S
1.2D + 1.0L
1.2D + 1.0L + 0.2S
1.2D + 0.2S

For instance:

### RE: ACI 318 (Load Combinations)

(OP)

So, it seems Clause 5.3.2 of ACI 318-14 is applicable to live loads (and to some extent snow load) as we have a choice on where to place it. I don't believe the same can apply to dead load, seismic load, wind load, and other environmental loads.

### RE: ACI 318 (Load Combinations)

Exactly. :) Any load that could be non-continuous at times. Judgement is required when altering uniform snow load, as the unbalanced condition is already covered by code, such as accumulation over parapet and roof obstructions. Alternate span load pattern can be both an unnecessary over kill, and unrealistic.
If equipment is present, you have ask yourself what might cause "if it is not there", unless it is rigidly build into the structure, which is rare.

### RE: ACI 318 (Load Combinations)

It's usually meant for live load, storage loads and such. I've done it for roof live load too. Not so much for rain or snow. That's handled more through ponding and snow drift concepts. But, you're free to do it for them too. I just don't see it as being directly applicable.

### RE: ACI 318 (Load Combinations)

r13, JoshPlumSE, If its a simple frame or system, applying patterned loads seems comfortable but how do you incorporate patterned loading for uneven spans and columns randomly placed in framing(I generally deal with projects on flat slabs so questioning considering that in mind).

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