Aashto guidance safety federal highway administration. Principal engineer city of spokane division of public works and utilities capital programsgis section august 31, 2004 scope. This loading is based on a hypothetical vehicle with one. Thus, the categorization of loads as permanent or transient is significant within the context of a probabilitybased specification. Loads esals during the analysis period is required. If values fo r moment and shear vary fr om girder to girder, separate tables shall be shown for each girder.
The front axle carried 8,000 pounds and the rear axle, 14 feet away, carried 32,000 pounds. Each system consists of individual truck loads and lane loads. Fatigue design for steel bridges load induced fatigue design for steel bridges according to the aashto going to cover. Pavement performance considerations for heavy traffic loads buses. Evolution of aashtobased bridge design southern plains. Aug 17, 2016 hl93 is a type of theoretical vehicular loading proposed by aashto in 1993. Fire truck loading using aashto lrfd msquared48 structural 21 dec 10 17. Dead load is usually represented by selfweight of girders, the weight of deck and superimposed dead loads. Standard vehicle live loads have been established by aashto for use in bridge. For twoaxial trucks aashto designates these vehicles as h series trucks. Read legal truck loads and aashto legal loads for posting. Traffic loads applied to the pavement system are usually in various combinations of axle loads and configurations, each having a specific damage effect.
A study on simple beam bridge responses due to thai truck loads. Pavement performance considerations for heavy traffic loads. Legal truck loads and aashto legal loads for posting. Officials aashto to provide loadequivalence factors for tridem axles aashto 1986. It is commonly called as hs20 44 where h stands for highway, s for semitrailer, 20 ton weight of the tractor 1st two axles and was proposed in 1994 2. There can be confusion since aashto published bridge design criteria, known as h20, which calls for truck axle loading of 32,000 lbs. Live loads for bridges in our previous discussions we mentioned that the primary live loads on bridge spans are due to traffic. Basic fundamentals of fracture mechanics crack initiation 2. The use of aashto lrfd bridge design specifications with culverts. Vehicular loads are typically based on the aashto h25 or hs25 configuration, figure 22, which represents a 25 ton 222 kn semi truck. Load and resistance factor design lrfd for highway. Hl93 is a type of theoretical vehicular loading proposed by aashto in 1993.
On both flexible and rigid pavements, the loadequivalence factor for a 20,000pound single axle is about 1. The heaviest loads are those produced by large transport trucks. Chapter 17 superstructure general january 2020 173 17. Aashto hl93 vehicular live load is a combination of three different loads, hl93 design truck formerly, hs2044 truck. The aashto road test and other studies have indicated that heavyvehicle wheel loads cause much greater damage to roads than do light loads. American association of highway and transportation officials aashto is a nonprofit association that represents highway and transportation departments across the nation and. Aashto states that truckinduced loads shall be excluded unless required by the owner for fatigue design of overhead traffic signal support structures. However, bridges in actual service tend to experience higher or lower load effects than the existing.
This report contains the findings of research performed to develop recommended revisions to the legal loads for posting as depicted in the manual for condition. The loadequivalence factors vary sharply with weight, following roughly a fourthpower relationship. Lrfd bridge design code aashto, 1998 contained numerous changes in loads and load applications, when compared to the aashto 15th edition asd code aashto, 1992 and the 17th edition aashto, 2002. Heavy duty steel design criteria ohio gratings, inc. The purpose of this paper is to identify and quantify the more significant, heavier.
Because all of the higher functional classifications have the. Legal truck loads and aashto legal loads for posting explores recommended revisions to the legal loads for posting as. Trbs national cooperative highway research program nchrp report 575. Applied live loadsapplied live loads 363d i l d f d k d k3. H20 and hs20 loading 8000 lbs 32,000 lbs h20 loading 8000 lbs 32,000 lbs hs20 loading 32,000 lbs 8002331510 dynamic load sample calculation wheel load wl 16,000 lbs 32,000 lb axle 2 dynamic force fd 1. Pedestrian loads, as described in the aashto lrfd bridge design specifications, shall be used to not only design the pedestrian railings on the structure, but shall also be used to design stairway railings that are adjacent to the structure and are part of the contract. Guide specification for wind loads on bridges during construction in 2015 aashto changed the format of the wind load design provisions from the fastest mile approach to the 3 second gust approach the pending construction wind load provisions were tabled until the completed bridge provisions could be implemented.
The american association of state and highway transportation officials aashto has a series of specifications for truck loadings. Aashto guidance american association of highway and transportation officials aashto is a nonprofit association that represents highway and transportation departments across the nation and serves as a liaison between state departments of transportation and the federal government. Legal truck loads and aashto legal loads for posting blurbs. For continuous structures, lane loadings may be continuous or discontinuous 4. Legal truck loads and aashto legal loads for posting explores recommended revisions to the legal loads for posting as depicted in the manual for condition evaluation of bridges, and the guide manual for condition evaluation and load and resistance factor rating lrfr of highway bridges. The 1944 edition included the hs20 truck load and started a policy of affixing the year to loadings making hs2044 the official.
Pdf thai truck weight limits rated by the department of highways. Minimum cover heights for corrugated plastic pipe under. The load factor for down drag loads shall be as specified in the aashto. Understanding the hs25 classification stormtank stormwater.
When the depth of fill is less than 2 ft, the wheel load shall. Thus, the estimated traffic loads expected to be applied to the pavement system are critical in determining the life expectancy of a given pavement systemstructure. Hs20 is the minimum design load recommended by aashto for bridges on interstate. Bridge analysis guide 4a3 federal operating rating 1. This factor is based on stress ranges due to the passage of the fatigue truck specified in article 3. Aashto specifications provide two systems of standard vehicle loads. Pdf legal truck loads and aashto legal loads for posting. There is a distribution width factor, e, for cantilever slabs given in section 3. Loads and forces on timber bridges usda forest service. The truck loads first used had the designation of h20 see figure 1, which covered a twoaxle truck weighing 20 tons. Hl93 aashto vehicular live loading truck tandem design. It is used as the design loading for highway structures in usa and other countries where aashto code is followed. Aashto lrfd bridgeaashto lrfd bridge design specifications. Applied live loads no lane load 363d i l d f d k d k3.
Vehicle loads for assessing the required load capacity. Axle load dual wheels truck traffic 15,60024,000 lb. Revised load and resistance factors for the aashto lrfd. Title legal truck loads and aashto legal loads for posting created published washington, d. Aashto lrfd main design loads and combinations dead loads. In general, the truck load controls for shorter span lengths and lane load controls for longer lengths 3. This is one of the factors included in the standard, in addition to dead load soil weight, surcharge loads, and all applicable loadsafety factors. General axle load equivalency factors that are indepen dent of pavementrelated variables and axle configurations and have a magnitude similar to the aashto axle factors are proposed. Thus, where large volumes of traffic with heavily loaded trucks are anticipated, an indepth analysis of the pavement thickness is important. The average annual daily traffic aadt in the base year. This theoretical live load hl93, defined as the design truck, is an hs20 load or 16,000 lbs. Similarly in railroad applications, the standard load is. As many lanes may be loaded as is required to produce the maximum desired effect 5.