Vehicular impact on boundary wall 1

[atika]

hi everybody
I'm designing a boundary walls in a residential area. I can't find anything in ASCE-7 or AASHTO directing me to design them to withstand vehicular impact.
can anyone guide me to find exact wording tells me that they are exempted from resisting vehicular impact?

 

[bridgebuster]

What do you mean by boundary wall? Is it a wall around a gated community? Anyway, the AASHTO LRFD spec is for a barrier on a bridge. The design loads are specified in Chapter 13. The loading depends on the type of traffic you expect; see 13.7.2 "Test Levels".

The AASHTO Roadside Design Guide may be of more use to you. It addresses barriers and railings for at-grade facilities.

 

[atika]

appreciate your prompt response.
the walls I'm designing are separating each housing unit within a large housing area ( 6000 villas). I'm just wondering if there is any provision in any official code forcing me to design these walls and their footings to vehicular impact in absence of any roadside barrier

 

[bridgebuster]

I took a look at the International Residential Code and didn't come across anything. To me, it sounds like you're building a privacy wall between adjacent houses and along the street. Unless you're required by your local code to prevent a vehicle from going through the wall just design the wall for the usual loads: dead, wind, seismic, etc.

Here's a way to look at it: Suppose there aren't any walls around the house, would you design the walls of the house to stop a vehicle? As an aside, about 30 years ago a car crashed into my uncle's house head on- don't recall how fast it was going - the basement wall stopped the car.

 

[ukbridge]

I had a similar issue designing the substructure for gantries in accordance with the Eurocodes, and agreeing the proper loads (if any) is an absolute nightmare. It depends on a great many things, such as proximity of the structure to the road, junctions etc. I'm not sure of the american way of doing things, but it might help speaking to the local authority.

 

[dhengr]

Atika:
It seems to me, that as an engineer, you have to ask questions like; what are the likely loadings and how likely are they, and what does it cost to design against these loads, and what does it cost to occasionally rebuild a section of wall if some drunken turkey does run into the wall? It seems to me, that more and more, many of you guys want the codes to tell you, “exact wording,” everything you can and can’t do, in every possible situation, and then to provide a design guide with worked out problems, into which you can plug your own particular numbers for the all perfect solution, for every possible problem, no thinking required. Did they ever tell you, during your engineering training, that sometimes you have to consider the various practical alternatives, and do a little free (but well informed) thinking, about reasonable solutions, to slightly unusual problems, and the codes may not cover them all. And, there may actually be some disadvantage to approaching the building authorities with your question directly. They might think it is a good and necessary idea/requirement, and double the cost of your walls, with little return or improvement to your project or the public safety and welfare. I suspect that 90% of the walls on the property are actually nowhere near any vehicular traffic and that the few lengths of wall needing it could be guarded by a few well placed large rocks with some flowers around them, called a garden, at a tee intersection for example. But, then you run the risk of some smart attorney claiming that your rock ran into the front end of his client’s car, while in a drunken stupor.

 

[BUGGAR]

Nobody's mentioned it but I remember reference to a 10 k guardrail alongside highways. At least that gives you a number and a context.

You could always put up Jersey barriers like all the highway contractors do to protect their workers. 'Course these ain't very pretty. Around here they get tagged with graffiti and politicians grant them to be street art and that works. Some of the better painted ones are actually sold to art patrons up in LaJolla.

If you don't want a highly visible barrier, you could plant a continuous line of those reverse spike tire shredders like in the exits of parking lots. Cars would lose some momentum after surfing one of these. Plant them in lots of tall grass and folks will never figure out how all four tires could go flat simultaneously.

 

[IRstuff]

Typically, boundary walls, even those adjacent to streets or highways, are not subject to impact requirements, because, the cost required to build something like that is prohibitive, given the likelihood of occurrence.

On the other hand, there are certain road layouts and speed limits that do lead to excessive occurrences of vehicle impacts. A friend once had a car crashing through his back fence and landing mere inches away from his kitchen window. The car was driven by a DUI, at 30 mph over the speed limit, etc., etc. But, his was only one house in the entire neighborhood that ever experienced anything like that in 50 yrs of the neighborhood's existence.

TTFN
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[drawoh]

atika,

Are you protecting homes from the crashing vehicles, or are you making sure the drivers and passengers of the vehicles survive the crash?

Are the vehicular impacts accidental or deliberate?

--
JHG

 

[atika]

I believe that they should not be designed to any vehicular impact load as they are not an essential part of the road. similar to noise walls, they themselves are not required to resist vehicular impact load unless they serve as traffic barrier or if they are attached to it. It makes sense to me, the additional cost will not be justifiable comparing to the actual occurrence of the collision as some of you mentioned.
I went through the codes and could not find anything about this particular subject. I just wanted to be sure that I'm not missing anything. thank you all for your help

 

[manstrom]

A "vehicle barrier" per IBC / ASCE would be required at the end of a parking space or drive aisle where the car could fall 12" or more - typically in a parking garage. The loading is 6000 lbs at 2'-3" (1'-6" under older codes).

You don't need to design for this if there is no fall greater than 12", nor is the area is not at the end of a parkign space or drive aisle.

If this is along a roadway, I'm out of my element. I assume there is an AASHTO standard for that.