Mohrs theorems for slope and deflection state that if a and b are two points on the deflection curve of a beam and b is a point of zero slope, then m. The beam is placed in contact with the surface under test between the vehicle tyres. How is benkelman beam deflection highway engineering abbreviated. Determine the equation of the deflection curve for a cantilever beam ab subjected to a uniform load of intensity q see figure. Benkelman in the united states and is often referred. Conjugate beam method the conjugatebeam method was developed by h. This device was introduced during the washo road test 1954 6, 1955 7. It was decided that 8 sets of observations of the benkelman beam deflection test may be taken. Standard guide for general pavement deflection measurements. By upgrading existing benkelman beams with electronic measurement sensors and data recording equipment then full deflection bowl data could be acquired with improved reliability when compared to manual methods of recording. Deflection should be find out by benkelman beam deflection test. Guidelines for deflection testing, analysis, and interpretation publication no.
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. The calculation technique will be explained in some examples. To lay down a uniform procedure for the design of flexible overlays using the benkelman beam deflection technique tentative guidelines of flexible road pavements using benkelman beam deflection technique irc. Overlay design by benkelman beam road surface standard. Benkelman beam consist of slender beam of length 3. The benkelman beam shall be calibrated for both range 2 and 3 prior to testing commencing. Electronic upgrade of a standard benkelman beam to enable.
Diagram showing critical dimensions of benkelman beam 2. Benkelman beam deflection technique road lane scribd. To verify the correct performance of the apparatus. Pavement evaluation by benkelman beam of state highway. However, at the 95 percent confidence level the bearing value of the section in. The hm574 benkelman beam is a simple leverarm device which measures deflection of flexible pavements under the action of moving wheel loads. General a the surface under the beam shall be sound and free of excessive loose material, large protruding. Benkelman beam deflection measurements 5 pages, 40 kb. Benkelman beam apparatus, asphaltbituminous mixture testing. The beam has a length l and a constant flexural rigidity. 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 tons to the axle vary. Hibbeler, 7th edition, prentice hall structural analysis, hibbeler, 7th edition, prentice hall. D4694 test method for deflections with a fallingweighttype impulse load.
General a the surface under the beam shall be sound and free. It should be used to find out the overlay thickness of the. For the love of physics walter lewin may 16, 2011 duration. Method aims determine the slope and deflection by using moment area method expected outcomes. Pavement evaluation and measurement of functional and structural. 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 most widely used method in india has been benkelman beam deflection bbd method. The following survey and tests will be conduct to compare deflection of flexible pavements by bbd and fwd techniques. Comparison of static modulus by benkelman beam bb test and dynamic modulus. This test method sets out the procedure for measuring the rebound deflection of a flexible pavement or road formation using a portable deflection beam under both a standard wheel load and tyre pressure. Able to analyze determinate beam deflection and slope by moment area method. Fhwahrt16011 december 2017 research, development, and technology turnerfairbank highway research center 6300 georgetown pike mclean, va 221012296. Benkelman beam apparatus, asphaltbituminous mixture. It should be used to find out the overlay thickness of the flexible over flexible pavement as per irc81 1997. The benkelman beam test requires two measurements to be taken, pavement deflection and distance from the loading vehicle. In the past, manitoba was using the benkelman beam rebound bbr deflection method for the rehabilitation design. Deflection testing of earthwork and pavement layers roads and. This pavement analysis tool provides the following features. Measures the deflection of a flexible pavement under moving wheel loads.
Development correlation between benkelman beam deflection and. Benkelman beam flexure and surface regularity impact. Examples illustrate the use of the deflection method in forecasting life and in. 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. Supplied complete with a wooden transport case 430mm x 1800mm x 350mm. History of benkelman beam deflection technique1 devised by a. Velciti done benkelman beam deflection for various state and cities roads and highways. Deflection of beam theory at a glance for ies, gate, psu 5. 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. The benkelman beam measures at a given point of the roadway the deflection caused by a wheel load. Bbd stands for benkelman beam deflection highway engineering.
Pddx pavement deflection data exchangetechnical data guide, version 1. Benkelman beam deflection technique free download as pdf file. Deflectometer rdd, benkelman beam deflectometer bbd. Benkelman beam deflection studies linkedin slideshare. Williot mohr diagram method virtual work method or unit load method the deflection. Sep 25, 2016 before that, deflection were measured by back calculation method of benkelman beam test to get material static modulus. Rebound deflection is defined as the amount of vertical rebound deflection of. D4602 guide for nondestructive testing of pavements using cyclicloading dynamic deflection equipment.
Calculate the slope and deflection at the free end. Collection and interpretation of pavement structural. The benkelman beam measures the deflection of a flexible pavement under moving wheel loads. Comparative studies between benkelman beam deflections bbd. A mixed approach, together with several environmental and structural adjustments, was used in pavement design for the new construction or reconstruction projects. Pdf conventionally in india overlay of flexible pavement design is carried out as per irc. A falling weight deflectometer fwd is a testing device used by civil engineers to evaluate the physical properties of pavement. Design of overlay for flexible pavement civil iitb. 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. Pdf mechanistic design of overlay based on benkelman beam. For instance, if the benkelman beam deflection is 0. The objective of the project deals with the identification of the deflections in the pavement at the regular intervals and design the overlay as per the site requirements, we find out the deflections using the benkelmans beam. Standard test procedure for benkelman beam deflection.
Comparative studies between benkelman beam deflections. With the beam free for operation, removal of the shim should result in a dial change of. Fwd data is primarily used to estimate pavement structural capacity for 1 overlay design and 2 to determine if a pavement is being overloaded. Deflection is measured when the vehicle passes over the test area. Pavement deflection is measured by the benkelman beam which consists of a slender beam 3. The probe beam, supported by a rigid reference beam, measures deflections using its 2. Structural deflectionsvirtual workunit load method dr.
Standard guide for nondestructive testing of pavements. The beam has a length l and a constant flexural rigidity ei. The most commonly used static deflection device is the benkelman beam. Static load deflection equipment measures the maximum deflection response of a pavement to static or slowly applied loads. Using fwd data with me design and analysis, volume iii. Bbd is defined as benkelman beam deflection highway engineering rarely. Directreading dial indicator eliminates need for conversion tables or field calculations. T256standard method of test for pavement deflection measurements. Before that, deflection were measured by back calculation method of benkelman beam test to get material static modulus.
Pdf evolution of the deflection according to truck. Dec 11, 2018 for the love of physics walter lewin may 16, 2011 duration. Larger pavement deflections imply weaker pavement and subgrade. This distance is frequently called the ttildititangential deviation to distinguish it from the beam deflection.
Benkelman beam deflection testing company india, tamilnadu. Evolution of the deflection according to truck overloading. Pdf comparative studies of lightweight deflectometer and. Adjustable feet for benkelman beam, complete with two spirit level calibration device 80b01803 calibration device for 80b0180 benkelman beam apparatus. Home asphalt road quality testing benkelman beam benkelman beam for flexible pavement deflection testing. As part of a pavement management system, supplementing the visual assessment of pavements, deflections by benkelman beam have been utilised for both the design of rehabilitation methods and their effectiveness. Surface deflection data from 320 mm thick conventional whitetopping overlay test sections at pune city, india was obtained using nondestructive test of. Both the fwd and instrumented benkelman beam are used in new zealand to measure the deflection bowl.
Benkelman beam deflection bbd part 1 tre highway engg. Benkelman beam deflection measurements waka kotahi nz. Pdf on jan 1, 2018, fatou samb and others published evolution of the deflection according to truck overloadingcomparison between benkelman beam method and fem of lateritic pavements find. Results of deflection measurement by benkelman beam method and determination of the characteristic deflection. If the dial gauge is functioning correctly, the beam pivot should be checked for free and smooth. 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. Deflection beam has been in use in india for more than two decades by different organizations. Horizontalreading, digital gauge for use with the benkelman beam.
By suitably placing the probe between the dual wheels of a loaded truck, it is possible to measure the rebound and residual deflections of the pavement structure. Deflected pavement structure bounce back to original shape deflected surface original position l o a d l o a d load removed 10. 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 is a deflection measuring device developed in 1953 by a. There must be no structures, such as trenches, culverts or pits, the test site must also be free of. You can see our benkelman beam deflection testing works below.
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