Vehicle Barrier System 2

[Kan155]

Hello, What is meant by the underlined system and where can i find this "approved method"?

"Vehicle barriers for passenger vehicles shall be designed to resist a concentrated load of 6,000 pounds (26.70 kN) in accordance with Section 4.5.3 of ASCE 7. Garages accommodating trucks and buses shall be designed in accordance with an approved method that contains provisions for traffic railings. This is from ASCE 7-16, chapter 4.5.3

Thank you!

 

[r13]

I think it meant to provide a design that satisfy the typical highway guardrail requirement (AASHTO, or Local DOT), with the consideration of the geometry of the driveway, the speed of the traffic, safety distance... etc. See the linked design guide from INDOT. Link

 

[bridgebuster]

I think OP is asking about bridge railing. Traffic railing Cited above is not the same as highway guardrail. Highway guardrail works like a rubber band and won't stop a vehicle from going through it if hit head on at a wide variety of angles.

 

[r13]

bb,

You got a very good point. I missed the words "Vehicle Barrier", but confused on "traffic railings". Seems ASCE meant a barrier to stop the specified 6000 lbs traffic force, rather than just block the path and guide the direction of the traffic. Note the tight space and low speed driving in the indoor garage, what is the typical DOT design for its own garage?

 

[bones206]

AISC Design Guide 18 has some detailed discussion and methodologies for designing vehicle barriers in parking garages. Whether or not that methodology is considered "approved" is probably at the discretion of the local AHJ.

 

[bridgebuster]

r13 - AASHTO LRFD Chapter 14 gets into the design of railing. There's a table of loads for the various test levels. Most people don't have access to AASHTO or want buy it (ain't cheap), however, NCHRP 350 is free and it was the basis of the AASHTO loads.

Link

You could also look at various DOT standard bridge railings, but they may be more than needed. Railings for bridges are usually TL-4 or TL-5; that's a 60K load.

 

[r13]

bb,

Thanks. You can tell the difference between a 60 kips and 6 kips forces. ASCE shall clarify what constitutes "an approved method that contains provisions for traffic railings"

 

[HTURKAK]

These are copy paste from ASCE 7-16


4.5.3 Vehicle Barrier Systems. Vehicle barrier systems for passenger vehicles shall be designed to resist a single load of
6,000 lb (26.70 kN) applied horizontally in any direction to the barrier system and shall have anchorages or attachments capable
of transferring this load to the structure. For design of the system,the load shall be assumed to act at heights between 1 ft 6 in.
(460 mm) and 2 ft 3 in. (686 mm) above the floor or ramp surface, located to produce the maximum load effects. The load shall be
applied on an area not to exceed 12 in. by 12 in. (305 mm by 305 mm). This load is not required to act concurrently with any
handrail or guardrail system loadings specified in Section 4.5.1. Vehicle barrier systems in garages accommodating trucks and
buses shall be designed in accordance with AASHTO LRFD Bridge Design Specifications.

...and the related commentary;

C4.5.3 Vehicle Barrier Systems. Vehicle barrier systems may be subjected to horizontal loads from moving vehicles. These
horizontal loads may be applied normal to the plane of the barrier system, parallel to the plane of the barrier system, or at any
intermediate angle. Loads in garages accommodating trucks and buses may be obtained from the provisions contained in
AASHTO LRFD Bridge Design Specifications, 7th Edition, 2014, with 2015 interim revisions.


Apparently , the situation is clear..

 

[r13]

There is some confusion here. I guess the OP has read a draft copy 0f ASCE 2016. Here is an article commenting the ambiguity of ASCE 2010 on the same section, which might have prompted the change/clarification. Link

Wish someone can provide the specified AASHTO provisions (regarding GARAGE traffic barriers/guardrails) to shed the light.

 

[r13]

The linked document is the MDOT "Bridge Railing Manual", I think it represents and satisfies AASHTO 2015 provisions. IMO, TL-3 (test level) is the most appropriate standard/criteria for mixed passenger cars, trucks and buses in a garage setting. Actually, TL-2 is arguably acceptable too. But I don't know if it is the case in the eyes of ASCE then. Link