Single HS20 Live Load in 1 Lane. How to relate that to load on multiple Bearing seats
Single HS20 Live Load in 1 Lane. How to relate that to load on multiple Bearing seats
(OP)
Hello, first time poster here. I am an entry level Project Engineer/Foreman for a bridge company. We have a bridge repair project at the moment that requires a live load calculation before we can begin. To summarize:
The Bridge needs to be jacked up half an inch along its bent 3 abutment. To do this we have 100-ton jacks under each(4) beam. The Highway Dept has given us dead load numbers to use so we know our jacks can handle this no problem.
We will flag the bridge and only allow 1 vehicle at a time across either way. What I need to do though is find out how much a single HS20 (80k lb) truck loading will increase the load on each bearing pad as that will be our worst case estimate. It's been a couple years since I had traffic in school so any help would be greatly appreciated.
Drawings are attached for clarification.
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The Bridge needs to be jacked up half an inch along its bent 3 abutment. To do this we have 100-ton jacks under each(4) beam. The Highway Dept has given us dead load numbers to use so we know our jacks can handle this no problem.
We will flag the bridge and only allow 1 vehicle at a time across either way. What I need to do though is find out how much a single HS20 (80k lb) truck loading will increase the load on each bearing pad as that will be our worst case estimate. It's been a couple years since I had traffic in school so any help would be greatly appreciated.
Drawings are attached for clarification.
Link
Link
Link





RE: Single HS20 Live Load in 1 Lane. How to relate that to load on multiple Bearing seats
BTW HS20 is a 72k truck, is 80k an Arkansas DoT requirement?
RE: Single HS20 Live Load in 1 Lane. How to relate that to load on multiple Bearing seats
When I was checking into HS20 everything I found said it is a 3 axle truck with the front axle at 12k and each of the back axles at 34k each for a total of 80k. 80k is also the legal limit for AR highways so I figured that would be the best to use for a conservative estimate.
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Thanks again.
RE: Single HS20 Live Load in 1 Lane. How to relate that to load on multiple Bearing seats
Also, I sketched out an HS20 truck. The one you have in your sketch is a variation of AASHTO Type 3-3, which is a real truck whereas HS20 is an imaginary vehicle. To play it safe check your loads with both trucks, unless ADOT specifies the 80k truck.