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Why You Need an Engineer to Determine Substantial Structural Damage

jar546

jar546

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Because it is essentially in the definition. Who else is qualified to determine this for situations where it is not obvious because of a total failure?

SUBSTANTIAL STRUCTURAL DAMAGE. A condition where any of the following apply:
  1. The vertical elements of the lateral force-resisting system have suffered damage such that the lateral load-carrying capacity of any story in any horizontal direction has been reduced by more than 33 percent from its predamage condition.
  2. The capacity of any vertical component carrying gravity load, or any group of such components, that has a tributary area more than 30 percent of the total area of the structure’s floor(s) and roof(s) has been reduced more than 20 percent from its predamage condition, and the remaining capacity of such affected elements, with respect to all dead and live loads, is less than 75 percent of that required by the International Building Code for new buildings of similar structure, purpose and location.
  3. The capacity of any structural component carrying snow load, or any group of such components, that supports more than 30 percent of the roof area of similar construction has been reduced more than 20 percent from its predamage condition, and the remaining capacity with respect to dead, live and snow loads is less than 75 percent of that required by the International Building Code for new buildings of similar structure, purpose and location.
For purposes of this definition, work done to implement repairs shall not be considered damage that reduces structural capacity.
 
All three conditions require two engineering calculations: one to calculate the pre-damaged structural capacity, and a second to calculate the post-damage structural calculation. And then a third calculation (which can be done by anyone using a $5 calculator) to compare the two capacities.

In my state, engineering can be performed only by licensed professional engineers. Ergo, something that specifically requires the performance of engineering calculations must be performed by an engineer. Architects (in this state, at least) are allowed to practice engineering -- when it is "incidental" to their architecture. So if I'm designing an entire building and I choose to perform my own structural engineering, I can do that (but I wouldn't). Where the work is specifically determining the reduction in structural capacity due to damage, it would be difficult to argue that such is incidental to architectural work, so I don't think architects would (or should) be allowed to do such work.
 
Inspectors are the first to respond when there is damage from fires, explosions and vehicle impact. I've been called in the middle of the night by the Fire Dept. many times to evaluate the structural integrity of a building. Many of us have an ID card from the Governor's Office Of Emergency Services with the duty to assess structures after a disaster strikes.

The engineer is involved in the fix but engineers are generally told what needs fixing.

So that's the typical day in the life of a La County building inspector. Jeff's post is for situations similar to the Florida condo collapse. A housewife can point to spalling concrete laying on the garage floor and an engineer can crunch numbers right up to the time of the event.
 
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ICE said:
Inspectors are the first to respond when there is damage from fires, explosions and vehicle impact. I've been called in the middle of the night by the Fire Dept. many times to evaluate the structural integrity of a building. Many of us have an ID card from the Governor's Office Of Emergency Services with the duty to assess structures after a disaster strikes.

The engineer is involved in the fix but engineers are generally told what needs fixing.

So that's the typical day in the life of a La County building inspector. Jeff's post is for situations similar to the Florida condo collapse. A housewife can point to spalling concrete laying on the garage floor and an engineer can crunch numbers right up to the time of the event.
Click to expand...
Most of us (all of us, I hope) can look at a hole where a car drove through a storefront or where a tree fell on a house and see whether or not any major load-carrying members have been impacted. But the question specifically cited code sections that require a determination that a structural element has been damaged such that its capacity is reduced by specific percentages in order for the damage to be classified as "Substantial Structural damage." Not even a licensed, experienced PE can make that determination by the Mk IV Mod 1A Hairy Eyeball method, unless the member(s) in question has/have been totally destroyed. To see if the reduction in capacity of a steel beam (for example) due to loss of 3/32" of lower flange thickness resulting from rust reduces the capacity of that beam by 20% or more requires performing calculations. And, at least in this state, performing those calculations requires a licensed PE. (Sure, any unlicensed monkey with access to the formulas can run the calculations -- but if they're not done by a PE and bear his/her seal and signature, we can't accept them.)
 
Thanks, I did not think to look at the IEBC for the definition since it was building structural committee definition.
[BS] SUBSTANTIAL STRUCTURAL DAMAGE

They should probably include it in the IBC definition on the next go round

Chapter 4 governs repairs and it is clear in 405.2.3.1 that a DP has to do the evaluation.
State laws would declare what type of license the DP would need.


[BS] 405.2.3 Substantial structural damage to vertical elements of the lateral force-resisting system.
A building that has sustained substantial structural damage to the vertical elements of its lateral force-resisting system shall be evaluated in accordance with Section 405.2.3.1, and either repaired in accordance with Section 405.2.3.2 or repaired and retrofitted in accordance with Section 405.2.3.3, depending on the results of the evaluation.

Exceptions:

1. Buildings assigned to Seismic Design Category A, B or C whose substantial structural damage was not caused by earthquake need not be evaluated or retrofitted for load combinations that include earthquake effects.

2. One- and two-family dwellings need not be evaluated or retrofitted for load combinations that include earthquake effects.

[BS] 405.2.3.1 Evaluation.
The building shall be evaluated by a registered design professional, and the evaluation findings shall be submitted to the code official. The evaluation shall establish whether the damaged building, if repaired to its predamage state, would comply with the provisions of the International Building Code for load combinations that include wind or earthquake effects, except that the seismic forces shall be the reduced seismic forces.
 
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