With the benkelman beam measurement method, the vertical deflection of the road. Published reports omitted important considerations which could influence measurement by the benkelman beam of deflection and curvature of flexible pavements under load. The popular methods used under non destructive pavement analysis are falling weight deflection method and benkelman beam deflection method bbd. Measures the deflection of a flexible pavement under moving wheel loads. Benkelman devised the simple deflection beam in 1953 for measurement of pavement surface deflection on the washto test road. With the benkelman beam measurement method, the vertical deflection of the road surface is measured after a defined load of 5 tons has rolled away. Evolution of the deflection according to truck overloading. Mechanistic evaluation of asphaltic pavement based on. Fkbbb correction factors of benkelman beam bb test load curve models of road deflection. The permissible maximum allowable benkelman beam deflection for satisfactory performance of a road stretch depends upon the traffic, material of construction, and the environmental factors. The magnitude of rebound deflection of a flexible pavements when a standard wheel. An alternative tool has been developed for measuring lte in whitetopping.
Figure 3 mounting brackets for benkelman beam f tape measure and pavement marker 1 chalk, paint or some other method of marking the pavement locations. Benkelman beam consist of slender beam of length 3. Elastic moduli are determent from pavement surface deflection. Deflected pavement structure bounce back to original shape deflected surface original position l o a d l o a d load removed 10. This unit is made from lightweight aluminium and features a telescoping design to reduce weight and storage space. Scribd is the worlds largest social reading and publishing site.
Deflectometer rdd, benkelman beam deflectometer bbd. Jun 26, 2016 the benkelman beam is the simplest and the oldest deflection test device, developed in the united states in the mid1950s. Experimental setup of benkelman beam deflection equipment the arrangement was made for benkelman beam deflection test on runway for evaluation of structural capacity of existing flexible pavement. Results of deflection measurement by benkelman beam method and determination of the characteristic deflection. Benkelman beam flexure and surface regularity impact. Benkelman beam deflection technique free download as pdf file. It should be used to find out the overlay thickness of the flexible over flexible pavement as per irc81 1997.
However, at the 95 percent confidence level the bearing value of the section in. Backanalysis of a measured deflection bowl is a widely accepted method for estimating the existing pavement materials elastic properties this is required for undertaking the rehabilitation treatments mechanistic design. Larger pavement deflections imply weaker pavement and subgrade. Deflection should be find out by benkelman beam deflection test. Calculate the ratio l of the deflection at the free end to the length, assuming that the beam carries the maximum allowable load. Benkelman beam deflection technique od4p6wzdowlp idocpub. One of the easiest and convenient ways of designing an overlay for strengthening is by using benkelman beam deflection bbd technique which measures the.
This definition appears rarely and is found in the following acronym finder categories. Sep 22, 2015 this test procedure covers the determination of the rebound deflection of a pavement under a standard wheel load and tyre pressure. The benkelman beam enables precise and non destructive measurements of the. Development correlation between benkelman beam deflection and. Overlay design by benkelman beam road surface standard. Comparative studies between benkelman beam deflections bbd. Mechanistic design of overlay based on benkelman beam. Direct reading dial indicator eliminates need for conversion tables or field calculations. Home asphalt road quality testing benkelman beam benkelman beam for flexible pavement deflection testing. The results of the deflection measurements from the fatickkaolack road with modulation of the axle load of 10, and 16 tons are given in table 1 the results showed that the values read on the beam in the case of the load of 10. Benkelman beam method ppt, benkelman beam method pdf, benkelman beam deflection method.
Both the fwd and instrumented benkelman beam are used in new zealand to measure the deflection bowl. Horizontalreading, digital gauge for use with the benkelman beam. Standard test procedure for benkelman beam deflection. The benkelman beam enables precise and nondestructive measurements of the. Benkelman beam deflection measurements 5 pages, 40 kb.
The new zealand transport agency nzta decided it should revisit the design of electronic instrumentation that could be attached to standard benkelman beams to measure surface deflection. According indonesian highways conditions 2005, the value of rebound deflection that measured by benkelman beam bb devices should be corrected by a factor of ground water table seasonal factors and. Esurveying softech offers bbd benkelman beam deflection highway engineering and bump integrator test services at economical prices. The benkelman beam measures the deflection of a flexible pavement under moving wheel loads.
This test procedure covers the determination of the rebound deflection of a pavement under a standard wheel load and tyre pressure. Deflection dx 4step procedure to solve deflection of beam problems by double integration method. Diagram showing critical dimensions of benkelman beam 2. Conjugate beam method castiglianos theorem virtual work method. Author links open overlay panel sunny deol guzzarlapudi vinod kumar adigopula rakesh kumar. It is widely used all over the world evaluation of the requirements of strengthening of flexible pavements. The beam is placed in contact with the surface under test between the vehicle tyres. The magnitude of rebound deflection of a flexible pavements when a standard wheel load of truck is moved forward is measured. Bbd stands for benkelman beam deflection highway engineering. Pdf mechanistic design of overlay based on benkelman beam. Benkelman devised the simple deflection beam in 1953 for measurement of pavement surface deflection. Comparative studies between benkelman beam deflections. Relationship is drawn between deflections readings measured by benkelman beam on x axis and deflections readings obtained by fwd on y axis.
We are offering benkelman beam apparatus, which measures the deflection of a flexible pavement under moving wheel loads in accordance with aashto test t256. In this work, benkelman beam deflection test has been conducted using two benkelman beams simultaneously placed on two adjacent slabs near transverse joint for measuring lte of 150 mm thick inservice thin whitetopping constructed at dahanukar colony, kothrud, pune city. Design of overlay for flexible pavement civil iitb. Deflection approach the structural strength of pavement is. Download our benkelman beam method ppt ebooks for free and learn more about benkelman beam method ppt. It is widely used all over the world for evaluation of the. You can see our benkelman beam deflection testing works below. How is benkelman beam deflection highway engineering abbreviated. The probe beam, supported by a rigid reference beam, measures deflections using its 2.
Benkelman beam deflection technique road lane scribd. Standard guide for general pavement deflection measurements. T256standard method of test for pavement deflection measurements. Rebound deflection is defined as the amount of vertical rebound deflection of a pavement surface due to the moving load bina marga, 2005. Ai deflection method the overlaid pavement is considered as a two layer. To determine the rebound deflection of a pavement under a standard wheel load and tyre pressure with or without temperature measurement by benkelman beam test. For instance, if the benkelman beam deflection is 0.
This method of test covers a procedure for the determination rebound. Able to analyze determinate beam deflection and slope by moment area method. Benkelman beam test scope this method describes the procedure for the determination of rebound deflection and curvature function of a flexible pavement under a standard wheel load, using the benkelman beam. The hm574 benkelman beam is a simple leverarm device which measures deflection of flexible pavements under the action of moving wheel loads. Pavement deflection is measured by the benkelman beam which consists of a slender beam 3. Thus the paper discusses about the linear, exponential and logarithmic relationship between benkelman beam deflection and falling weight deflectometer for the edge and. The method also describes the procedure for the calibration of the deflection data acquisition system ddas and bwl4 manual, queensland.
Specifications for measurement condition survey and deflection data are used to establish sections of uniform performance at least 10 deflection measurements should be. Sep 11, 2015 test method for determination of elastic modulus of pavement structure using benkelman beam, with each country have standard about it vi. Its used to measure the structural capacity of a flexible pavement. Strength evaluation of flexible pavement of runway using. Collection and interpretation of pavement structural. History of benkelman beam deflection technique1 devised by a. Pdf evolution of the deflection according to truck. These books contain exercises and tutorials to improve your practical skills, at all levels. Benkelman beam deflection method for evaluation of structural capacity of existing flexible pavements and design of overlay phase 1 this paper reports on the first phase of a study of the benkelman beam method, sponsored by the indian ministry of surface transport. This has been attempted several times in the past but resulting devices were often complex and expensive. Benkelman beam deflection testing company india, tamilnadu. And strengthening is the most adopted method as a pavement maintenance measure. It was decided that 8 sets of observations of the benkelman beam deflection test may be taken. The vertical deflection is recorded by a special measuring beam, which is mounted on a support frame that can be rotated at a ratio of 1.
The most widely used method in india has been benkelman beam deflection bbd method. The design traffic in terms of cumulative standard number of axles is to be used. Velciti done benkelman beam deflection for various state and cities roads and highways. Pavement evaluation is a technique of assessing the. Electronic upgrade of a standard benkelman beam to enable. The benkelman beam is the simplest and the oldest deflection test device, developed in the united states in the mid1950s. Evolution of the deflection according to truck overloadingcomparison between benkelman beam method and fem of lateritic pavements. The development included planning the measurement process, choosing the necessary accessory equipment, designing. Benkelman beam deflection bbd test benkelman beam is less expansive deflection measuring equipment and method of study is simple and easy to carry out.
Pavement evaluation by benkelman beam of state highway. Pddx pavement deflection data exchangetechnical data guide, version 1. Benkelman beam for flexible pavement deflection testing. Benkelman beam deflection testing company india, roads and highway testing services, deflection testing company india, highway consultants. The method also describes the procedure for the calibration of the benkelman beam. Comparative studies of lightweight deflectometer and. The benkelman beam deflection method is thus widely used for evaluation of structural capacity of existing flexible pavements and also for estimation and design of overlays for strengthening of any weak pavement for highways. Referenced documents purchase separately the documents listed below are referenced within the subject standard but are not provided as part of the standard aashto standard. The deflection of the pavement after the corrections i. It is a convenient and practical device for measuring deflection of flexible pavements under the action of wheel loads. Manufactured from aluminium alloy and supplied complete with dial gauge and accessories, the benkelman beam is used to measure the road surface deflection when under load from vehicle wheels. Correlation between deflections measurements on flexible. The results of the deflection measurements from the fatickkaolack road with modulation of the axle load of 10, and 16 tons are given in table 1.
Based on present study, graphical method which deflection dependent was developed to determine parameters of elasticity. The beam is a steel wideflange section with e 28 106 psi and an allowable bending stress of 17,500 psi in both tension and compression. Bbd stands for benkelman beam deflection highway engineering suggest new definition. Also given is the method for computing allowable spring axle load from the test data. The benkelman beam deflection method is thus widely used for evaluation of structural capacity of existing flexible pavements and also for estimation and. Benkelman beam conducted under washo method to collect data in order to find deflection condition of existing pavement.
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