If your application varies from the values given on this table, contact Fibergrate Engineering for application assistance. Looking through the AASHTO code, I didn't find anything applicable to spanning with plate steel. 2 of the AASHTO LRFD Bridge Design Specifications. , M. 4. The finite-element method was used to investigate the effect of span length, slab width with and without shoulders, and wheel load conditions on typical bridges. The AASHTO live-load distribution equations presented in Table 1 and Table 2 remained essentially unchanged for interior girders. In order to simplify the computation of load distribution, AASHTO Standard It is important to note that these factors are applied to wheel loads (multiply by 1/2 if. The 40,000-pound proof load signifies a 2. Beam-and-Slab Bridge Wheel Load Distribution. This report presents the findings of the research performed on distribution of wheel loads on highway bridges under funding from the National Cooperative Highway Research Program (NCHRP). . Wood, J. , which is different from the Wheel Load Distribution Factor defined in the AASHTO Specs. 3. LRFD utilizes load combinations called limit states which represent the various loading conditions which structural materials must be able to withstand. This chapter deals with highway bridge loads and load distribution as speciﬁed in the AASHTO Load and Resistance Factor Design (LRFD) Speciﬁcations [1]. The current AASHTO Specifications are unrealistic and too conservative in most cases. 0 for a single lane (a single lane equals two wheels). Relationship of Slab Thickness and Girder Spacing in. For over 30 yr the "Standard Specifications for Highway Bridges" of the American Association of State Highway Officials (AASHO) has in-·eluded a procedure for determining this load distribution. Due to the improbable coincidence of other loads, the analysis may be limited to the impact load and dead loads with a load factor of 1. Distribution Statement No restrictions. H. 30, and the maximum deflection of the bridge was L/1500. 24 CFR 200 . L. Ronald Hudson, presents experimental data on the effect of tire inflation pressure and static wheel load on contact pressure distribu Calculations with this amount of steel using AS procedures with stresses, materials, covers, and live load distribution appropriate to the AASHTO Bridge Specifications for the estimated date of construction should give at or very near an H-10, H-15, or perhaps an H-20 theoretical rating. Pennings, K. The HL93 “design tandem” wheel load is 12,500 pounds compared with the “Alternate Military Load” of 12,000 pounds. 04 was utilized according to AASHTO 1996 Table 3. This project seeks to calculate live load distribution factors via live load test, and determine what, if any, category the NEXT section can fall under for simplified moment live load distribution factors. Some specifiers use an H-20 or HS-20 load; the load (12 ft) subject to various loads or load combinations of dead load, earth pressure, and live load. 67 (A615 steel) Discussion on AASHTO LRFD Load Distribution Factors for Slab-on-Girder Bridges C. The development of Sep 11, 2007 The enclosed VDOT Modification is made to the AASHTO Standard “Wheel Load Distribution of Steel Bridge Plank,” by Conrad P. yield strength to ultimate tensile strength γ3 = 0. the relationship of live load design moments and shears, obtained from the refined analysis, to the live load moments and shears obtained from a standard line girder analysis with a live load distribution factor of 1. Frank, S. Deflection results were lower than the AASHTO L/800 limit. 0. 19. AASHTO LRFD Bridge Design Specifications, Sections within AASHTO LRFD. AASHTO LRFD Bridge Design Specifications, hereafter referred to as AASHTO LRFD. Highway Live Loads on Concrete Pipe Foreword Thick, high-strength pavements designed for heavy truck traffic substantially reduce the pressure transmitted through a wheel to the subgrade and, consequently, to the underlying concrete pipe. Heins,. 3. Case (A). Axle Load Dual Wheels Modi˜ed AASHTO H-20 20,800 2 (C)*+ 20" 20" Truck Traf˜c 24,000 lb. This method Feb 25, 2003 Adoption as the AASHTO Design Guide Axle Load Distribution Factors. Lever Rule For Computation Of Live Load Distribution Factors In CONSPAN [TN] AASHTO, Bridge, CONSPAN, distribution factors, LEAP Bridge, Lever Rule, TechNote LOAD RATING OF NEW BRIDGE DESIGN. 6. E. vehicle) AASHTO H-5 vehicle weighing 10,000 lbs: 8,000 lb and 2,000 lb axles with a minimum 72-inch wheel base. 0 4 kN/m2) for future bituminous wearing surface. data on the effect of tire inflation pressure and static wheel load on contact pressure distributions for the bias Goodyear 18-22. Furthermore, the girders were designed assuming no composite action with the panels. - 2,500 lbs. 1 to determine live load distribution factors. 36', therefore, I assume that for a 16k wheel load, I would have 16/4. Designers use H-20 or HS-20 from AASHTO, or specific axle configurations, to express the extreme load effect created by heavy vehicles such as transports, buses and fire trucks. The HL93 “design truck” wheel load is the same as the HS20 wheel load. This is a hypothetical Live Load Model proposed by AASHTO for analysis of bridges. A collegue of mine asked me about the proper wheel load distribution for H-20 loading on a temporary "road plate" used to cover a trench. 10,000 lbs 40,000 lbs 10,000 lbs 40,000 lbs 40,000 lbs H-25 Loading HS-25 Loading Rainstore3 has been independently ˜eld and labaratory tested to meet H-20 Bridge Loading. I am designing the slab based on a 1'-0" strip. The HL-93 Live Load is the design live load for bridges designed under Load and Resistance Factor Design (LRFD). The wheel load distribution factor was determined to be S/5, a dynamic load allowance was determined to be 0. 67x6/4= 5. Bridge rehabilitations and widenings are to be designed using either LFD or LRFD, at the designer’s option. 5 Tires," by Rex William Hansen, Carl Bertrand, Kurt M. For loads in other positions on the span, the distribution for shear shall be determined by the method prescribed for moment, except that the calculations of horizontal shear in rectan load to be applied to the “Strength II” limit state. TRB’s National Cooperative Highway Research Program (NCHRP) Report 647: Recommended Design Specifications for Live Load Distribution to Buried Structures explores recommendations to revise the American Association of State Highway and Transportation Officials Load and Resistance Factor Design Bridge Design Specifications relating to the distribution of live load to buried structures. • The definition of f s has been revised to reflect the current code language. load distribution factors used to assign live load demands to individual girders. 8, respectively. Mar 15, 2004 WHEEL LOAD DISTRIBUTION IN SIMPLY SUPPORTED CONCRETE The AASHTO bending moment gave results similar to those of the FEA A detailed method for accurately modeling wheel loading from overload trucks . Design Specifications , hereafter referred to as AASHTO LRFD. In addition to the pavement effect, the fill conditions (i. 17. 30 Tire Contact Area rev 7/2015. This isolated beam is subjected to loads comprising one axle of the design vehicle multiplied by a load fraction “g. •Standard APPENDIX D AASHTO Interior Girder Distribution Factor . •Mean wheel location = 18 in. ~. Load based on the AASHTO Standard Truck Load as defined in AASHTO LRFD Bridge Design Specifications, 2nd Ed. LATERAL LOAD DISTRIBUTION ON TRANSVERSE FLOOR BEAMS IN STEEL PLATE GIRDER BRIDGES by K. CHAPTER 2 DESIGN DATA 2-1 Variations from Current AASHTO LRFD StandardBridge Design Specifications and Interims Article 3. The AASHTO approach (Ref 5) is to calculate an "effective" width, E, over which the concentrated wheel load is assumed to be uniformly distributed: E = 4. A wheel load distribution factor of 1. ALLOWABLE SPAN IS STRONGLY DEPENDENT ON WHEEL WIDTH AND VEHICLE WEIGHT/LOAD CAPACITY. (of report) TRB’s National Cooperative Highway Research Program (NCHRP) Report 647: Recommended Design Specifications for Live Load Distribution to Buried Structures explores recommendations to revise the American Association of State Highway and Transportation Officials Load and Resistance Factor Design Bridge Design Specifications relating to the distribution of live load to buried structures. Level 1 methods provide simple formulas to predict lateral load distribution, using a wheel load distribution factor applied to a truck wheel line to obtain the longitudinal response of a single girder. The span is 6'. per axle with a minimum 96-inch wheel base. EXAMPLE 2: COMPUTATION OF LEVER RULE FOR INTERIOR BEAM. Distribution of Wheel Loads to Stringers, Longitudinal Beams and Floor The wheel load distribution factor from the “S-over” equation, the AASHTO standard equation (AASHTO 1996), for concrete slab on steel girder bridges with two Jul 28, 2010 How will the new AASHTO loading specifications affect you? The HL93 “design truck” wheel load is the same as the HS20 wheel load. 0 ft. those as part of the Design Request definition together with wheel spacing,. The most common historical approach is to convert damage from wheel loads of various magnitudes and repetitions (“mixed traffic”) to damage from an equivalent number of “standard” or “equivalent” loads. , P. Current AASHTO guidance on wheel load distribution widths for timber slab bridges load rated using Allowable Stress may be conservative and results in unnecessary Title Live Load Distribution Factors For A Three Span Continuous Precast Girder Bridge Publication No . Loads Distribution Thomas Saad, P. Key Words Load equivalency concept, load equivalency factor, AASHTO 18-kip equivalency concept 18. 26,000. 751. July 1989 Report No. Allowable stresses are discussed in subsequent chapters, according to the type of material. where one‐lane distribution factor in the pavements present above the fill while determining the load distribution. A plank element is modeled as a beam on elastic supports. However, for narrow bridges with roadway widths less than 18 ft. O. 9. 2 (C)*+ 25". , Frederick G. Aug 29, 2016 The Distribution Factor Analysis feature computes live load distribution factors for location and vehicle wheel description entered by the user. 7) If the structure is located within the limits of the one hundred (100) year flood plain, use the - live load distributed to top slab per sections 3. 2016 AASHTO LRFD Specification Update Frank Russo, PhD, PE T5 –Loads and Load Distribution to Wheel Load Cycling 5. For reinforced concrete boxes, when the depth of fill is two feet or less, the wheel load shall be distributed as in slabs with concentrated loads. . It was found that the presence of secondary elements can result in a load distribution factor up to 40 % lower than the AASHTO LRFD value. A future Load spectra ¾ME-PDG (AASHTO 2002 Design Guide) ¾Quite complex, requires a lot of data Vehicle class distribution (10 heavy vehicle classes) Axle load distribution single axles for each vehicle class Axle load distribution, tandem axles for each vehicle class Axle load distribution, triple axles for each vehicle class distribution of truck load to plank decks. dead load is included with the dead load of the panel. AASHTO rating loads, based on standard structural analysis practices. 2. org Lateral distribution of the wheel load shall be that produced by assuming the flooring to act as a simple span between stringers or beams. Distribution of Wheel Loads Through Earth Fills. law. 12. D. , fill thickness and fill modulus) may affect the load distribution. edition (1) (AASHTO Standard), provides a distribution width of live loads when Jan 5, 2013 AASHTO: Standard Specifications for Highway Bridges. TABLE 2. AASHTO LRFD Slab-on-Beam Bridge Live Load Distribution Factors T he slab-on-beam bridge live load distribution factors of the AASHTO LRFD Bridge Design Specifications were originally developed by Imbsen & Associates Inc. The AASHTO LRFD (2012) introduced new wheel load distribution factors based on published research in the last few decades. ), Tarhini K. Concrete Each wheel load distributed between intersecting strips by ratio. 2, MOMENT DISTRIBUTION FACTOR FOR INTERIOR BEAMS (Aashto Lrfd 4. Axle Load Dual Wheels Modi˜ed AASHTO H-25 26,000 2 (C)*+ 25" 25" Truck Traf˜c 32,000 lb. In addition to highway bridges, there are a large number of bridges located on secondary roadways where farm calculating load equivalency factors, if necessary. Federal Highway Administration Chicago, IL AASHTO Load and Resistance Factor Design (LRFD) Goal: develop more comprehensive specifications to: Eliminate any gaps & inconsistencies in the AASHTO Standard Specifications, Incorporate the latest in bridge research, Achieve more uniform margins of safety or (12 ft) subject to various loads or load combinations of dead load, earth pressure, and live load. The current culvert designs are according to the AASHTO Standard Specifications. Yura, and J. 5. Non-composite dead loads (slab, girder) shall be distributed longitudinally to girders assuming simple supports and transversely to girders according to tributary widths. Live Loads for Bridges The AASHTO standard H20 and HS20 trucks Live Loads for Bridges The AASHTO specifications also allow you to represent the truck as a single concentrated load and an uniform load. (1/2 axle load +. In bridge design, a live (or truck-wheel) load distribution method is required to simplify AASHTO LRFD (2005) bridge-design specification also uses equations Wheel Load. The four finite-element modeling techniques yielded similar load distribution factors. is the 18,000 lb (80 kN) equivalent single axle load (normally designated ESAL). The NEXT beam cross section does not fall into an AASHTO LRFD category for simplified moment live load distribution factors. The main objective of this research was to investigate the impact of the wheel-line spacing of dual-lane loads on the lateral load distribution on bridges. 25’ used by Erps, etal (8). Another example of a small vehicular live load is a maintenance vehicle that weigh 5,000 lbs. BrR has the ability to compute the Standard Specification live load distribution factors for you based on the corrugated deck definition. This study deals primarily with this problem of wheel load distribution through soil and attempts to develop theoretical and experimental data for comparison with the current AASHTO specifications and to provide a smooth transition for the entire range of effective fill heights. TIRE LOAD (Ibs,) 6000 7000 BOOO Figure 12 Tire Deflection Versus Tire Load Maximum vertical contact pressure of these two tire types at their typical steer and drive/trailer axle loads/inflations are . These specifications introduced the provision of distributing single or multiple wheel live loads to the The AASHTO live-load distribution equations presented in Table 1 and Table 2 remained essentially unchanged for interior girders. Key Words Loads, Load Combinations, Steel Bridge Design, Load Factors, Limit States 18. 5 and Smooth 11R24. 2”. The second problem, pertaining to load distribution through HL-93 Design Truck (formerly, HS20-44 Truck) HL-93 Design Tandem (formerly, Alternate Military) Design Lane Load; Details of application and calculation of Design Vehicular Live Load is explained in “AASHTO Bridge Design Specifications Cl 3. Cai, P. LOAD RATING OF NEW BRIDGE DESIGN. S. The wheel load distribution factor equations from the AASHTO Standard Specification (AASHTO 1996) are called “S-over” equations, which is AASHTO specifications for highway bridges have been revised several times based . Federal Highway Administration Chicago, IL AASHTO Load and Resistance Factor Design (LRFD) Goal: develop more comprehensive specifications to: Eliminate any gaps & inconsistencies in the AASHTO Standard Specifications, Incorporate the latest in bridge research, Achieve more uniform margins of safety or beam distribution for the estimation of the wheel load distribution factor. Standards to be used in the the live load moments and shears obtained from a standard line girder analysis with a live load distribution factor of 1. 1, and the live load impact factor was 0. This specification requires castings to keep a proof load of 40,000 pounds applied on a 9-inch by 9-inch pad in the center of the casting. HL-93 is used in Load Rating when calculating the Federal Inventory and Operating Rating for bridges To improve the state policy and AASHTO code specifications, it is necessary to understand the actual effects of wheel-line spacing on lateral load distribution. terms of wheel loads, as with AASHTO (2002). 35 Dead Permanent Loads For all bridge floors, except those on movable spans, the design dead load shall include an additional 20 30 lbs/ft2 (1. The live-load distribution equations in the AASHTO LRFD Specification, provided in Table 2, were attained by adjusting the AASHTO Standard Specification equations, provided in Table 1, from wheel loads to lane DISTRIBUTION OF WHEEL LOADS ON HIGHWAY BRIDGES. g. adjacent spans, and offsetting the trucks to investigate the load distribution. shown in FIGURE 13. This. Load Distribution. lids for concrete vaults). 2 for Service III resistance limits). Report No. For H20-44 and HS20-44: Concentrated load 18 kips for moment 26 kips for shear Uniform loading 640 lb/ft of load lane The Use of AASHTO LRFD Bridge Design Specifications with AASHTO AASHTO (12,00 lb per STD) HS 20 LOAD ALTERNATE LOAD. 5 tires. 0 + 0. ” NCHRP. The corresponding lane load distribution factor according to AASHTO 1998 LRFD Table tribution for haunched deck panels (Ref 4) concluded that AASHTO load distribution design allowables could be increased up to 45 percent for 20-foot spans. 32, distance from the lane edge to the wheel line. A wheel load is one-half of the axle load. STRAND, MICHAEL A. Stream ﬂow, ice loads, vessel collision loads, loads for barrier design, loads for anchored and mechanically stabilized walls, seismic forces, Wheel Load (lbs) (1/2 axle load + 30% impact) Load Distribution Parallel with Axle Perpendicular to Axle Truck Traf˜c 40,000 lb. e. M. 2 Vehicular Live The size of the “standard truck” and the distribution of its weight is reported in the AASHTO code. Accordingly, the critical factor in the analysis is the lateral distribution of wheel loads to the bridge components. This has resulted in the posting of these bridges, restricting traffic and impacting commerce. CA YES An experimental test program to evaluate the behavior of a 0. ASCE2 Abstract: Live-load distribution is an important step in the analysis of bridge superstructures. distance It accounts for wheel load impact from moving vehicles. 4-scale model of a two-span continuous plate-girder bridge with modular precast prestressed concrete deck panels has recently been completed. Please refer to the latest edition of the AASHTO LRFD Bridge Design Specifications4 for details of this design load. This document is available to the public through the National Technical Information Service, Springfield, Virginia 22161. This AASHTO procedure has been criticized for being conservative due to its approach for using simplistic load distribution factors. Live Load Distribution throughLive Load load combinations to assist the designer in avoiding non-governing load combinations. The pressure reduction is so great that generally the live load can be neglected. These specifications introduced the provision of distributing single or multiple wheel live loads to the The live load distribution factors contained in the AASHTO-LRFD Bridge Design Specification present a major change to the AASHTO-LFD specifications that have been in effect for more than 50 years. Load-Induced Fatigue A wheel load distribution factor of 1. configuration, Figure 2-2, which represents a 25 ton (222 kN) semi-truck. Similar load distribution characteristics were observed in the transverse and longitudinal directions. Background Precast concrete box culverts are typically designed as highway bridges per either AASHTO Standard (2002) or LRFD (2012). The distribution factor is the Reaction, R, is independently computed about the Hinge on both the right and the left sides. The where is the slab thickness in cm, is the wheel load in kg, is the radius of the wheel load distribution in cm, the radius of the relative stiffness in cm and is the radius of the resisting section in cm SECTION 3: LOADS AND LOAD FACTORS 3-3 21 This design criterion typically applies to pier columns and non-redundant through type superstructure elements, such as through trusses or through arches. The formulas developed in this study for the level 1 analysis were based on the standard AASHTO HS truck. R. 23. II90-2F, "Truck Tire Pavement Contact Pressure Distribution Characteristics for the Bias Goodyear load distribution factors for comparison with the AASHTO LRFD simplified live load distribution factor equations, namely the Lever Rule Method. The bias-ply tire generates lower peak pressures than the radial-ply tire, in the order of about -12% Vehicular loads are typically based on the AASHTO H-25 or HS-25. General Traffic . and Resistance Factor Design (AASHTO LRFD) do not account for the presence of wheel load distribution in simply-supported, one-span, one- and two-lane May 2, 2019 specified, all code references refer to the AASHTO LRFD Bridge Live Load distribution factors are calculated by first finding the . GRUBB, AND LLOYD R. Case 2: H-5 truck (10,000 lb. You can click the ‘Compute from Typical Section…’ button and BrR will compute the distribution factors. The loads used to design the longitudinal girders are determined by the application of a specified AASHTO wheel load distribution factor, which is a function of girder spacing. ASCE1; and Genmiao Chen, P. 10 The distribution of the wheel load in both directions are analyzed below: S = span length H = Depth of ground cover on top of culvert Case 1 - Traffic travels parallel to span of buried structure Live load distribution parallel Live load distribution transverse Calculations with this amount of steel using AS procedures with stresses, materials, covers, and live load distribution appropriate to the AASHTO Bridge Specifications for the estimated date of construction should give at or very near an H-10, H-15, or perhaps an H-20 theoretical rating. Dynamic *AASHTO 3. ” This “g” is defined as Axle Load Distribution Factor in LRFD Specs. If you leave these fields blank, the AASHTO LFD engine will compute the distribution factors for distribution width is less than the span or diameter, the applied pressure for design purposes, shall be the total load divided by the span or diameter. Axle Load Dual Wheels Modi˜ed Method to Compute Live-Load Distribution in Bridge Girders Jingjuan Li, Ph. ) Ratio of specified min. 2) The AASHTO-LRFD Specifications allow the use of advanced methods of analysis to determine the live load distribution factors. 1. 1 Qualitative example of AASHTO load distribution procedure. Parallel Axle Load. The corresponding lane load distribution factor according to AASHTO 1998 LRFD Table specifications provide simplified formulae to determine Live Load Distribution Factors (LLDFs) for highway bridges. Material properties, in particular MOE and MOR, are based on the actual test data. The models are developed using LARSA 4D software. 10 Distribution of Live Loads to Substructure Units . Although LATERAL LOAD DISTRIBUTION ON TRANSVERSE FLOOR BEAMS IN STEEL PLATE GIRDER BRIDGES by K. “…where the Specifically, the wheel load distribution factors and impact factors as defined by AASHTO were considered in order to assess the load transfer and distribution in Aug 29, 2014 AASHTO: AASHTO Standard Specifications for Highway Bridges (17th Ed. The distribution of the wheel load through a pavement may be different from that suggested by the current AASHTO guidelines. Assignment. Wheel-Load Distribution Results from AISI-FHWA Model Bridge Study MARK MOORE, KARL A. Do not use AASHTO distribution factors for the line girder analysis. 1190-1, "Truck Tire-Pavement Contact Pressure Distribution Characteristics for Super Single 18-22. Once the. Table 2-2: AASHTO LRFD (1998) Girder distribution factors for Table 1. 1 Live Load Distribution Factors (S4. 4. BSS01011999-2 Abstract This design example illustrates the procedure for calculating live load distribution factors for the approximate method of analysis described in Article 4. For pre-stressed concrete bridges, the NYSDOT Design Permit Vehicle shall also be used for the “Service III” limit state as a design load case in addition to the AASHTO HL93 live load (see Article 5. It is very important to remember that AASHTO LRFD uses axle load and lane load, instead of wheel load. In the direction of the deck span, no longitudinal distribu tion of wheel loads is assumed, and wheel loads act as concentrated loads. Bridge rehabilitations and Note A: Position wheel loads within the design lane such that the effect being considered May 2, 2000 3. A. (Reinforcement paralell to traffic) This gives 4. Security This paper presents the results of a parametric study related to the wheel load distribution in one-span, simply supported, multilane, reinforced concrete slab bridges. AASHTO's H-20 and HS-20 are live load ratings applied to the design of bridges or other suspended items (e. wheel from the back axle starts to load the bridge, the strain increases to a new peak. The results of these modeling techniques were compared with AASHTO wheel load distribution factors (in 1996 and in 1994) and published experimental results. The live load distribution factors contained in the AASHTO-LRFD Bridge Design Specification present a major change to the AASHTO-LFD specifications that have been in effect for more than 50 years. 5 and the smooth radial Armstrong 11R24. loading provisions given in AASHTO LRFD Bridge Design Specifications and AASHTO Bridge There are two classes of design live loads recommended by AASHTO, truck load computation as well for the distribution of wheel loads applied at the end of a tested to meet H-20 Bridge Loading. 06S (feet) Loads and Loads Distribution Thomas Saad, P. 6 Wheel Load for Deck Design . In view of the complexity of the theoretical analysis involved in determin ing lateral wheel-load distribution, AASHTO specifications give empirical In 1989, the AASHTO published the AASHTO M306 and revised it in 2005. values of the AASHTO Standard Specifications. If Only One Lane is Loaded The first wheel line is placed directly over the interior girder of interest to generate the largest reaction. This paper introduces a new framework to compute live-load distribution for bridge girders. 67k/ft(not including impact)and a moment of 3. ➢ The “H” three wheel forces as they pass over the point C . 30% impact). 2b). (lbs). 5 safety factor over the H-20 design load of 16,000 pounds. When the depth of fill Load distribution may also be influenced by the type and spacing of beam bracing or dia phragms, but the effect of these components is not considered for deter mining load distribution. Dead load shall be applied to the following structure types as follows: For Steel or Concrete Girder Structures. , through National Cooperative Highway Research Program (NCHRP) Project 12-26, Distribution of Wheel Loads on Highway Bridges Comprehensive Design Example for Prestressed Concrete (PSC) Girder Superstructure Bridge Design Step 5 Design of Superstructure Design Step 5. 25". Jirsa Research Report 1746-3 Research Project 0-1746 EFFECTS OF OVERLOADS ON EXISTING STRUCTURES conducted for the Texas Department of Transportation in cooperation with the Vehicular loads are typically based on the AASHTO H-25 or HS-25. 5) Surcharge load: Assume 2 feet of earth cover, unless other information is available. Dual Wheels. Aug 17, 2016 AASHTO HL-93 vehicular live load is a combination of three different loads, the design lane load shall be assumed to be uniformly distributed 17. Load dispersion through soil is also discussed, and the relevant AASHTO provisions are reviewed and compared with field measurements and with theoretically predicted values by using the Boussinesq elasticity solution. The formulae for the AASHTO code-specified LLDFs have been developed, considering the effect of typical highway trucks. ANALYSIS The following cases were analyzed using AASHTO and Westergaard‘s (3) solutions to get a historical perspective of the wheel loads effects on bridge decks. 06S. H 300 DESIGN LOADS AND DISTRIBUTION OF LOADS H 310 GENERAL REQUIREMENTS All structures should be designed to sustain, within the allowable stresses, all applicable design loads and forces which are properly distributed. • The definition of α 1 was added. 3 Distribution of Dead Load to Girders . AASHTO-LRFD LIVE LOAD DISTRIBUTION SPECIFICATIONS By Toorak Zokaie,1 Member, ASCE ABSTRACT: The live load distribution factors contained in the AASHTO-LRFD Bridge Design Speciﬁcation present a major change to the AASHTO-LFD speciﬁcations that have been in effect for more than 50 years. I am designing a concrete top for a roadway box. 60 (non-segmental brg. S. Longitudinal cracking was found to increase the load distribution factor; the resulting load distribution factor can be up to 17 % higher than the LRFD value. is the wheel load in pounds. one-dimensional beam. FEA wheel load distribution and bending moments comarepared with reference bridge slabs without railings as well as to the AASHTO design procedures. Beam-and-Slab Bridges . 19’, which is similar to the 1. 75 and 0. ASCE1 Abstract: The present study developed a new set of formulas for load distribution factors that are more rational than the current AASHTO LRFD formulas. load case. Security Classif. • The modular ratio will now be taken as an exact value as opposed to assuming a value of 9. Jul 6, 2018 3, LRFD LIVE LOAD DISTRIBUTION FACTORS. The live-load distribution equations in the AASHTO LRFD Specification, provided in Table 2, were attained by adjusting the AASHTO Standard Specification equations, provided in Table 1, from wheel loads to lane 3. developing more realistic design criteria for distribu,~ion of wheel loads on highway bridges. : Wheel load distribution in I girder 1. “Distribution of wheel loads on highway bridges. resource. The design edge beam width, E, for 1-line of wheel loading (½ lane) shall be taken as:. Grasspave2 Wheel load = WL= 16,000 lbs (32,000 lb axle / 2). • The load factors for Fatigue I and Fatigue II have been increased to 1. Chapter 2 describes the historical background of the AASHTO wheel load distribution formula and summary of relevant research studies. 36 or 3. 1996 AASHTO Standard Specification, Wheel Load Distribution Factors [ 1] 2005 AASHTO LRFD Design Specification, Lane Load Distribution Factors Apr 3, 2018 For the case of the uniformly distributed lane load, the 0. Provides a more accurate formula to calculate the live load distribution factors The live load distribution factors in LRFD method is approximately half of these in the standard specifications. goal of this research was to determine the following AASHTO bridge design parameters: wheel load distribution factor g, dynamic load allowance IM, and maximum deflection. Reason for proposing this live load model is to prescribe a set of loads such that it produces extreme load effect approximately same as that produced by the exclusion vehicles. Equating this area for a 16 K wheel load to a circle results in a diameter of 1. are calculated using the load on one rear wheel of a truck. According to the FEA results, the presence of railings he reduces t longitudinal bending moment inthe concrete slabs by 25% to 60% depending on the stiffness of the railings in (AASHTO) Standard Specifications for Highway Bridges. Marshek, and W. Lever Rule For Computation Of Live Load Distribution Factors In CONSPAN [TN] AASHTO, Bridge, CONSPAN, distribution factors, LEAP Bridge, Lever Rule, TechNote 4) Traffic loads: AASHTO H20 wheel load with appropriate impact factor. Longitudinal glulam panels are designed as individual members to resist applied loads. 6) Lifting loads: Design precast structures for lifting loads. This document is available to the public through the National Technical Information Service, Springfield, VA 22161. Jirsa Research Report 1746-3 Research Project 0-1746 EFFECTS OF OVERLOADS ON EXISTING STRUCTURES conducted for the Texas Department of Transportation in cooperation with the EXAMPLE 6 - DECK DESIGN, INCLUDING COLLISION ON A TYPE 7 & TYPE 10M BARRIER 6 2019 Where: Flexural cracking variability factor γ1 = 1. Dec 3, 2002 beam, pultruded structural beam, wheel load distribution, dynamic load . 4, BEAM-SLAB BRIDGES, Last . The most commonly used equivalent load in the U. The major part of the load model is axle load, and in particular wheel load. 6 and 4. 4 Dead Load Distribution. Furthermore, it is not the wheel load but rather the damage to the pavement caused by the wheel load that is of primary concern. Based on my research, AASHTO(1992 edition) gives a distribution width of 4+. Modified AASHTO H-25. 1 Elevation view of . The models use the Eccentric Beam modeling techniques previously discussed in section 5. Some specifiers use an H-20 or HS-20 load; the load • If using the simplified live load distribution equations in the AASHTO Specifications, choose the appropriate equation based on the number of design lanes (one lane or multiple lanes). R. Transversely, the design lane load is assumed to be uniformly distributed The single nominal wheel load is specified as a 100 kN load placed on the Jan 8, 2016 Girder distribution factors (GDFs) were compared to AASHTO equivalent values. In-place load test strain data are used to compute wheel load distribution widths and estimates for bending moments acting on unit widths of bridge deck. These widths are compared with those computed using the AASHTO-LRFD and AASHTO Standard specifications. 13 of nonlinear finite element analyses. 51 ft-k. Determine Wheel Load Fraction for live load distribution. Results from . A comparison of old versus new indicates that the difference is very small. aashto wheel load distribution