Axle load shifts during truck braking and their implications for bridge and pavement design

1989 ◽  
Vol 16 (2) ◽  
pp. 113-118 ◽  
Author(s):  
B. G. Hutchinson ◽  
L. R. Rilett ◽  
R. Green ◽  
R. C. G. Haas
Keyword(s):  
Urban Areas ◽  
Load Transfer ◽  
Front Axle ◽  
Pavement Design ◽  
Bridge Design ◽  
Load Increase ◽  
Reference Design ◽  
Bridge Damage ◽  
Load Tests ◽  
Pavement Damage

The axle load shifts of four truck types during braking are estimated using theoretical braking models and the implications of these axle load shifts for bridge and pavement design are explored. The truck types examined are a three-axle straight truck, a five-axle tractor semi-trailer, a seven-axle tractor semi-trailer with two air-lift belly axles, and a seven-axle B-train tractor-double trailer, each loaded to legal Ontario limits with weigh-out commodities. Each of the truck types experienced a substantial load transfer to the front steering axles under braking, mainly from the rear tandem axle groups, where the front axle load increase varied from 38 to 48%. The bridge design implications of the load shifts are examined in terms of the Ontario Bridge Formula and the moments induced in simple-span bridges compared with the moments induced by a reference design truck. For the braking model used, the decelerations and associated shifts in axle load do not lead to higher forces for bridge design and evaluation. The pavement damage implications are analyzed in terms of load equivalency functions derived from some load tests conducted at a number of pavement sites across Canada in 1986. These equivalencies increased up to 50% of the static values for the three-axle truck at maximum braking. It is suggested that the major damage implications are at intersections in urban areas and that increased structural sections could be designed to handle the increased equivalencies. Key words: bridge design, pavement design, truck braking, truck loads, pavement damage, bridge damage.

Uplift behaviour of tapered piles established from model tests

2000 ◽  
Vol 37 (1) ◽  
pp. 56-74 ◽  
Author(s):  
M Hesham El Naggar ◽  
Jin Qi Wei
Keyword(s):  
Load Transfer ◽  
Compressive Loading ◽  
Compressive Load ◽  
Tensile Load ◽  
Confining Pressure ◽  
Cohesionless Soil ◽  
Uplift Capacity ◽  
Experimental Modelling ◽  
Confining Pressures ◽  
Load Tests

Tapered piles have a substantial advantage with regard to their load-carrying capacity in the downward frictional mode. The uplift performance of tapered piles, however, has not been fully understood. This paper describes the results of an experimental investigation into the characteristics of the uplift performance of tapered piles. Three instrumented steel piles with different degrees of taper were installed in cohesionless soil and subjected to compressive and tensile load tests. The soil was contained in a steel soil chamber and pressurized using an air bladder to facilitate modelling the confining pressures pertinent to larger embedment depths. The results of this study indicated that the pile axial uplift capacity increased with an increase in the confining pressure for all piles examined in this study. The ratios of uplift to compressive load for tapered piles were less than those for straight piles of the same length and average embedded diameter. The uplift capacity of tapered piles was found to be comparable to that of straight-sided wall piles at higher confining pressure values, suggesting that the performance of actual tapered piles (with greater length) would be comparable to that of straight-sided wall piles. Also, the results indicated that residual stresses developed during the compressive loading phase and their effect were more significant on the initial uplift capacity of piles, and this effect was more pronounced for tapered piles in medium-dense sand.Key words: tapered piles, uplift, axial response, load transfer, experimental modelling.

Instrumented load tests in mudstone: pile capacity and settlement prediction

2002 ◽  
Vol 39 (6) ◽  
pp. 1254-1272 ◽  
Author(s):  
J R Omer ◽  
R Delpak ◽  
R B Robinson
Keyword(s):  
Load Transfer ◽  
Load Capacity ◽  
Large Diameter ◽  
Soft Rock ◽  
Site Investigation ◽  
Alternative Methods ◽  
Vertical Loading ◽  
South Wales ◽  
Pile Design ◽  
Load Tests

The present work stems from the design of a viaduct in South Wales, U.K., where full-scale pile testing was carried out to assess whether the proposed design methods would meet the required load capacity and settlement criteria for the working piles. Five fully instrumented large diameter bored cast in situ piles, up to 30 m deep, were installed in weathered mudstone and tested under vertical loading. A sixth pile, which had no shaft instrumentation, was formed with a voided toe. In conjunction with vast soil data from 218 site investigation boreholes, the extensive data produced from the load tests were analyzed to quantify the key parameters considered to influence load transfer and settlement behaviour. Each pile was first calibrated using four methods to establish the as-built stiffness, taking into account the nonlinearity of concrete and the effect of partial steel encasement. It is demonstrated that the current national norms for bored pile design in cohesive soil – soft rock are overconservative for South Wales ground conditions. To ameliorate this, alternative methods are proposed, which lead to improved reliability and accuracy in shaft and base capacity assessment. In addition, a numerical model is developed that can be used to predict the complete load-settlement variation up to the ultimate state. The model is sufficiently expounded to allow its immediate application in pile design by geotechnical engineers.Key words: piled foundations, load tests, bearing capacity and settlement, Mercia mudstone.

scholarly journals DEVELOPMENT OF OVERWEIGHT PERMIT FEE USING MECHANISTIC-EMPIRICAL PAVEMENT DESIGN AND LIFE-CYCLE COST ANALYSIS

Transport ◽  
2016 ◽  
Vol 31 (2) ◽  
pp. 156-166 ◽  
Author(s):  
Hao Wang ◽  
Jingnan Zhao
Keyword(s):  
Life Cycle ◽  
Cost Analysis ◽  
Life Cycle Cost ◽  
Fatigue Cracking ◽  
Pavement Design ◽  
Life Cycle Cost Analysis ◽  
Damage Cost ◽  
Local Data ◽  
Traffic Loading ◽  
Pavement Damage

The study aims to determine rational overweight permit fee using Mechanistic-Empirical (M-E) pavement design and Life-Cycle Cost Analysis (LCCA). The state-of-art pavement design software, Pavement-ME, was utilized to develop Load Equivalency Factors (LEFs) and estimate pavement service life under various traffic loading conditions. LCCA was conducted to calculate Marginal Pavement Damage Cost (MPDC) in terms of Equivalent Uniform Annual Cost (EUAC) considering variations in maintenance strategies, analysis periods, and discount rates. A methodology framework was established to calculate distance based, weight based, weight and distance based, and flat permit fee for overweight trucks. With the local data obtained in New Jersey (United States), example permit fees were determined for the major and local road network with the thick and thin asphalt pavement structure, respectively. It was found that the truck-induced damage cost varied significantly between thin and thick asphalt pavements considering different failure mechanisms in fatigue cracking and rutting. In general, overweight permit fee may not be fair to overweight trucks at different vehicle classifications if only the total overweight tonnage is regulated in the permit fee structure.

Design of bored piles in residual soils based on field-performance data

1991 ◽  
Vol 28 (2) ◽  
pp. 200-209 ◽  
Author(s):  
M. F. Chang ◽  
B. B. Broms
Keyword(s):  
Load Transfer ◽  
Large Diameter ◽  
Design Procedure ◽  
Field Performance ◽  
Residual Soil ◽  
Residual Soils ◽  
Weak Rocks ◽  
Load Tests ◽  
Bored Piles ◽  
Load Displacement

The current practice for the design of large-diameter bored piles in residual soils in Singapore is based on the calculated static capacity of the piles. Insufficient consideration of the load-transfer mechanism and overreliance on pile load tests have led to conservative designs. A better alternative is to adopt a load–displacement analysis method that provides information on the load distribution along the pile and the complete load–displacement relationship. Results of full-scale load tests on instrumented piles indicate that bored piles in residual soils in Singapore behave in the same way as in stiff clay and weak rocks elsewhere in that the load transfer at the working load is dominated by shaft friction. Simple correlations exist between the standard penetration resistance and the load-transfer parameters. An example illustrates that the proposed design procedure that uses these simple correlations and the load-transfer method is an improvement over present design methods. Key words: bored piles, cast-in-place piles, design, drilled piers, field test, load transfer, residual soil, shaft resistance.

Reliability of Traffic Data

1998 ◽  
Vol 1625 (1) ◽  
pp. 18-25
Author(s):  
Wiley D. Cunagin ◽  
Perry M. Kent
Keyword(s):  
Performance Evaluation ◽  
Policy Development ◽  
Pavement Design ◽  
Traffic Data ◽  
Bridge Design ◽  
Administrative Policy ◽  
Data Variability ◽  
Data Files ◽  
And Performance ◽  
Transportation Applications

The results of an investigation into reliability of traffic data are presented. Accurate and reliable traffic data are essential to a wide variety of transportation applications, including pavement and bridge design and performance evaluation, programming, planning, and budgeting activities, as well as legislative and administrative policy development. Millions of dollars are spent each year to collect, process, and disseminate these data to users. The development of the AASHTO reliability concept for pavement design was investigated and expressions for traffic data variability were developed. Extensive actual traffic data files were analyzed. The resulting statistics were used to determine the importance of traffic data variability on the reliability of traffic projections for pavement design.

Modelling of Road Damage Potentials of Tandem C-Dolly

2007 ◽  
Author(s):  
Jose A. Romero ◽  
Alejandro Lozano
Keyword(s):  
Experimental Study ◽  
Load Transfer ◽  
The Other ◽  
Lateral Stability ◽  
Damage Potential ◽  
Longitudinal Load ◽  
Optimum Speed ◽  
Articulated Vehicles ◽  
Pavement Damage

The paper deals with the pavement damage potential of long combination vehicles equipped with tandem C-dolly. Due to its double-hitch bar design, the tandem C-dolly enhances the lateral stability of the articulated vehicles; however, its single articulation could create significant levels of longitudinal load transfer between the coupled bodies and posing higher pavement damage. The pavement damage potentials of vehicles equipped with tandem C-dolly is compared with that of vehicles equipped with standard tandem A-dolly. For pavements with a roughness lower than 2 mm/m the effect of tandem design is only marginal. For pavements with roughness greater than 2 mm/m, results suggest an optimum speed (95 km/h) at which C-dolly is 1% less damaging than A-dolly. However, for the other two speeds evaluated (75 and 115 km/h), C-dolly is up to 12.1% less friendly than A-dolly. Such increases in road damaging potential are significant and an experimental study should be performed to validate results.

Cost of Pavement Damage Due to Heavier Loads on Louisiana Highways: Preliminary Assessment

2000 ◽  
Vol 1732 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Freddy L. Roberts ◽  
Ludfi Djakfar
Keyword(s):  
Pavement Design ◽  
Design Parameters ◽  
Preliminary Assessment ◽  
Design Data ◽  
Present Worth ◽  
Gross Vehicle Weight ◽  
Pavement Damage ◽  
The Cost ◽  
Government Statistics ◽  
The Impact

A preliminary assessment is made of the impact of increasing the gross vehicle weight (GVW) from current legal limits to 100,000 lb (45 400 kg) on vehicles hauling sugarcane, rice, timber, and cotton. Sections of road were chosen in each area of Louisiana where commodities are produced, the amount of each commodity hauled was estimated, and the effects of increasing the GVW were evaluated for each section using pavement design models. Design data were secured from the Louisiana Department of Transportation and Development computer database and project files to determine the pavement design parameters and traffic estimates for each road. The number of vehicles hauling the 1998 harvest payload was estimated, a projected increase in the production of each commodity was estimated on the basis of government statistics, and rehabilitations were designed with the use of the 1986 AASHTO Design Guide for a 20-year analysis period. Present worth (PW) was calculated for each GVW scenario for each roadway. Comparisons of PW between the weight scenarios showed that increases in GVW have more effect on state and U.S. highways than they do on Interstate highways. Any increase in GVW over current limits increases the cost of overlays and decreases the length of time before an overlay is required. The cost increase due to increasing the GVW is substantial. Fee structures should be modified by the legislature so that these costs are paid for either through the current registration and overweight permit fee structure or through some new tax, such as a ton-mile tax.

Predictive Indoor Wheel Testing of Heavy Duty Truck Tires

1987 ◽  
Vol 15 (1) ◽  
pp. 58-67
Author(s):  
R. L. Keefe
Keyword(s):  
Load Transfer ◽  
High Stress ◽  
High Load ◽  
Heavy Duty ◽  
Low Speed ◽  
Service Failures ◽  
Heavy Duty Truck ◽  
Truck Tire ◽  
Truck Tires ◽  
Load Tests

Abstract An indoor wheel test for heavy duty truck tires has been developed to predict in-service failures of commercial and developmental tires. The test, run at slow speed and high load to emphasize stress and fatigue rather than heat, is based on the premise that repeated high stress is the principal cause of in-service tire failure. These stresses occur when dynamic or transient overloads are caused by road bumps, load transfer during braking and cornering, or dual tire configuration on non-uniform surfaces. Although these overloads may occur infrequently, they can become very significant in the long distances run by truck tires. Other current heavy duty truck tire tests are generally run at higher speeds, emphasizing heat resistance of rubber compounds, or else are low-speed, much-overloaded bead tests which are unrealistically severe. Since its development in 1974 the present test has been broadly predictive for many belt, carcass, or fatigue related in-service failures of both bias and radial commercial and developmental truck tires. The test is called “The DuPont High Load Wheel Test” to distinguish it from other low-speed-high-load tests.

Modular Footbridges of Guadua Angustifolia Kunth

2015 ◽  
Vol 668 ◽  
pp. 218-226
Author(s):  
Fabián Augusto Lamus Báez ◽  
Carlos Felipe Urazán Bonells ◽  
Sofía Andrade Pardo
Keyword(s):  
Urban Areas ◽  
Soil Stabilization ◽  
Weight Ratio ◽  
Growth Cycle ◽  
Fixation Rate ◽  
Truss Bridges ◽  
Pedestrian Bridges ◽  
Load Tests ◽  
Bridge Building ◽  
Short Time

In South America, especially in the Andean region, many communities are isolated and their development is limited due to the difficulties in communicating with urban areas, because the lack of adequate road infrastructure. Most of this problem is due to economic issues and lack of attention from governments. Moreover, the Guaduaangustifolia Kunth (Guadua-a.) is a bamboo that grows in most of the Americas. This material has a resistance – weight ratio similar to structural steel also presenting additional benefits such as soil stabilization, flow regulation, and a high CO2 fixation rate to the ground. In addition the Guadua-a. growth cycle spans from 3 to 5 years. All of these makes the Guadua-a. in highly renewable material. This paper presents an alternative for the construction of Guadua-a. structural modules for pedestrian bridges, as a solution to the lack of infrastructure in village roads and even in suburban areas. In the proposed model, the bridge would be built by the community in a short time, taking advantage of existing Guadua-a. in the area, and establishing an industrialized cultivation of it, to enable them to have enough material for maintenance and replacement of sections as necessary. A numerical structural analysis was performed to determine the maximum possible span under load specifications from Colombian bridge building code. The results shows that a bridge up to 21m of span can be constructed using the module. The span can be increased drastically when the module is combined with wire-cable or an arc shaped configuration, however, the module was assessed to be used in straight truss bridges because this setting carries the largest loads on the elements. Real scale load tests were conducted on a full scale physical model of the module, the structural elements and the connection between the modules.

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