The trucks that you list are all 'design' vehicles. That is, they are basically mathematical fictions (and not actual vehicles), specified for the single purpose of establishing acceptable design loadings for bridges or whatever.
For the purpose that they have been specified, there would be no point in indicating a set of 'unloaded vehicle loads'. For engineering design purposes, one would either assume the presence of a vehicle loaded to its full design value, or no vehicle at all. The in-between case of partly loaded vehicles would not usually be relevant.
If you want to know actual vehicle masses, I suggest that you look elsewhere.
I have a load limitation 11 Tons per axle on one of the waterfront structure. We need to find out what is the maximum load that can be hauled over it. We have various trucks like concrete mixers, dump trucks etc. that has to pass on these structure. Unfortunately, the configurations of the trucks that the client proposes to use is not clearly defined.
While I was aware of the fact that HS20 is a theoretical truck, I thought 3, 3s2 and 3-3 were the wheel configuration of actual trucks. Thanks for the info. Otherwise I would have been running in circles.
load on tundem rear axlec of concrete mixer is up to 46,000 lbs (23 tons). Use 25 tons to be on safe side, or search the web for more info.
You may concider impact.
I'm lost here...If you have an 11 tons per axle load limit as defined by your structure and yet you're looking for the maximum load that can be hauled across it??? Isn't it 11 tons??? I guess what you mean is what is the truck that you must limit - which is not at all based on truck but axle weight anyway. You would simply post a sign showing the restrictions. If you're responsible for access to a construction site then perhaps bolstering the weak element would be in your favor.
By inspection, you can't use a HS vehicle as the axle load is 32kips or 16 tons and this is without impact. Most states will require impact unless the speed is somewhere around 5-10 mph. Using the HS vehicle would give you, in my opinion, blanket approval, if it worked for all vehicles as it is a fictional truck designed to effect the maximum load.
For other truck weights I suggest that you contact some of the truck manufacturers or concrete delivery folks - you may want to have them stop at a weight station if one is close enough by.
It will be very hard to inventory this and even more so to enforce the load limit. I also hope there is a nice, warm and fuzzy safety factor in the 11 tons.
You might JUST consider installing an access ramp to your wharf, over which all trucks would have to pass, and which would deflect excessively (sounding a LOUD limit-switched alarm) under a 11 ton axle. With modern technology, you might possibly arrange for the alarm to shout at the driver "Get that x#@*~! truck off my wharf".
If you want to limit the maxim axle load to 11 tons, the following load limits need to be set for the trucks you have listed:
HS: 24 Tons
H: 13 Tons
Type 3: statutory vehicle (25 tons) has maxim axle load of 8.5 tons (but 2 are only 4 feet apart)
Type 3S2: statutory vehicle (36 tons) has maxim axle load of 7.75 tons (but 2 are only 4 feet apart)
Type 3-3 statutory vehicle (40 tons) has maxim axle load of 8 tons (but 2 other 7 ton axles are 4 feet apart)
It is true that these are fictitious design vehicles, but DOTs Post bridges this way all of the time. The way you come up with the maximum truck load is by using the following equation:
Posted Weight = (Allowable axle load / Maximum design vehicle axle load) x Design Vehicle weight
This assumes that you will only get one axle on the bridge at a time. If more than one axle is on the bridge, the analysis becomes more complicated.
The AASHTO Manual for Condition Evaluation of Bridges has a handy table that gives you the Live Load Moment due to all 5 types of trucks listed above on a longitudinal stringer for simple spans ranging from 5 to 300 feet. This table takes into account the effect of multiple axles on the bridge
Thank You all for your responses. My original question remains unanswered. My client is a General Contractor who has to drive concrete and material truck on the 500 ft. long wharf. The load restriction on the wharf is 35T vehicles and the axle wt. not to exceed 11 Tons. I have to advice the client as to how much concrete and debris he can haul on the pier. Obviously, none of the trucks can be loaded to full capacity. If I have the axle loads when the trucks are empty, then I can calculate the load that I can add-on to arrive at the limit of 11 Tons/axle. Since the configuration of trucks used varies, I am trying to find out the allowable haul for the five standard (theoretical) truck types.
Alternatives of Strengthening the wharf is not feasible due to the cost. Only other alternative would be to barge in/out the material.
I don't think using the theoretical trucks will help you in this situation (as they are theoretical and not tied to an unloaded or partially loaded real-life truck). You need to get actual axle configurations and weights in order to complete this task.
If the contractor is serious about using the trucks to haul materials then weighing the actual trucks in use would be well worth the time and expense - no one, especially you and your employer, wants a collapsed wharf. Otherwise, use the barge. If the contractor needs to know if it is possible, then get them to weigh each truck they plan to use to determine axle loads, and then limit the loads such that axles do not surpass the 11 ton limit. ~dison
It seems to me that you need to know the span length of the spans at the warf and the axle spacing. If the span length of the warf is sufficiently short, then you will be determining the allowable truck weight based on the design tandum, two axles four feet on center. If the spans are less than sixteen feet then I believe this will serve as a basis for an analysis. If the span gets up over twenty feet, then you may have to consider the front three axles as a combination. I hope this helps.
If I may; who owns the warf? Who determined that it was OK for an 11 ton vehicle? They may have information you should consider before you get back to the client with a final answer.
Finally, you may want to consider a make shift weigh station to protect you in this case, although if an overweight truck collapses the warf, he won't be able to leave the area before you get a chance to have him weighed.
I’d go with weighing the trucks. There are portable weigh scales available that can weigh one axle at a time or a complete truck. The cost to set one up is not significant as they are common on road construction.
The advantage is that you will have a record of each truck so that if after the job there is any question if the wharf was overloaded then you can demonstrate due diligence in keeping the weights within the allowable.
If you are looking for a number for bidding purposes, most truckers know their tare weight.(i.e. empty truck) you can then calculate the number of deliveries needed for the volume of material
Rick Kitson MBA P.Eng
Construction Project Management
From conception to completion
As I've mentioned above weighing the vehicles is certainly appropriate.
You also propose another good alternate that is available. Barging. I've worked on many jobs where barging was the an alternative and it worked to everyone's satisfaction. Of course, this assumes that you already have a tug handy. All the jobs I had did so it was just a little more scheduling for the day of the big pour/delivery etc.
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