Ac 3.01535 2200 | LIBRARY Mich aan State wenn eam ee ee ee ee ee PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before date due. DATE DUE DATE DUE DATE DUE MSU Is An Affirmative Action/E qual Opportunity Inetitution c\cire\datedus.pm3-p. 1 DESIGH OF CONCRETE BEAM TESTING MACHINE --200000--- A Thesis Submitted to fhe Faculty of MICHIGAN AGRICULTURAL COLLEGE ‘ Eo C eS a H. H. Himebaugh RS 1) MoGaw om _ Candidates for the Degree of Bachelor of Science. July, 1919. THESIS INTRODUCTION. When the fire of March Sth, 1916 destroyed the Engineering Hall and shops at M.A.C. it also, destroyed all the departmental equipment. The more necessary articles were replaced as soon as possible in order that the college work might be continued without interruption. However, some things were not replaced immediately, and among them was a machine for testing concrete beams; @ very necessary part of the Civil Engineering Department's equipment, for without a machine of this nature it has been impossible to obtain the best results in Masonry Design. In conferring with Professor Vedder upon a thesis subject this year he suggested that a machine to test conorete beams for flexure be designed and built, and as the writers were interested in concrete design, they decided to take this subject for a thesia and by doing eo afd to their knowledge of concrete design, and, also, leave a useful instrument with the college. The writers wish to express their appreciation to Professor Vedder for his help and many valuable suggestions as to the design of such e machine, and, also, to Messrs. Hool and Johnson, the authors of the Concrete Engineers Handbook which was used as reference thruout the work. 101878 HISTORY. Before starting our work we studied the design of similar machines that are on the market, for we wished to make ours as practical as possible. After looking thru the various manufacturers catalogues we decided on the design shown on the following pages of this thesis. We chose hydraulic jacks as the means of applying the required pressures in the testing of beams, because the engineering department owned two available jacks that were not likely to be used for any other purpose. Upon the suggestion of Professor Vedder the machine was designed for the maximum duty of breaking a reinforced concrete beam four by twelve inches in cross-section and twelve feet in length. Using a beam of the above dimensions as a standard and a basis of calculation, we computed the ultimate foroe that would be required to break it. To this result we applied a factor of safety of five and derived the sise of our machine base. After our general design was approved we started collecting the materials for the base-beam. The form was. constructed of matched pine lumber that had been previously used in a shed door; so we were assured that it was thourly dried and would not warp. The work of building the form was carried on as rapidly as possible in order that the conorete might be poured and have at least twenty-eight days in which to set before undertaking the assembling of the machine. The concrete was mixed with a minimum percentage of water and well tamped in the form. After setting it was sprinkled with water several times a day for the first two weeks. Due to the fact that when in use the tension side of the base-beam will be the top, we poured the base-beanm up side down, and in this way avoided the necessity of having to work the concrete thra the reinforcing ateel which is required in the top of the base-beam when the machine is assembled. When the base-beam had set four weeks, we rolled it over using two pump jacks for the purpose, and when it was in position the machine was assembled and put in working order. DESCRIPTION. The assembled concrete beam tester, shown in Fig. l, was constructed in the cement laboratory. In designing it was found that the beam would stand the load without etirrups by placing thirteen 11/16"x16' round mild steel rods in the top of it. But this amount of steel was near the stress point and the writers decided to add stirrups in order to mke it absolutely safe. 80 two rods 5/16"xl6' were placed in the bottom to hook the stirrups over and then stirrups of 5/16" round rods were placed four inches apart for a distance of five feet four inches from each end of the beam. See Fig. 2, for the placing of the steel. fhe rods were held in place by wiring to the form and then after the beam had set the wires were out. After stripping the beam it was decided to paint it with cement to make a smooth finished surface. The hydraulic jacks, rods and plates which were to be used had been thru the fire and, of course, were in a very rusty condition. To remove the rust they were first thorly soaked with kerosene and afterwards the rust was removed with sandpaper. The parts were then painted with machine enamel. In drawing sketches and designe the writers decided to make the pump base of a concrete hollow square with a hardwood top. The base is made of 1:2:4 conorete with 1/4" deformed reinforoing rods at the corners. See Fig. 3. The outside dimensions are 18" x 24" and the inside 10" x 16" 4 allowing a four inch wall. In order to fasten the hard- wood top to the concrete base it was decided to use six machine bolts inbeéded in the concrete. In providing enough bond strength on these bolts, 1/2" x 10" machine bolts were requisitioned, and a two inch right angle bent on the end, These were inbedded in the concrete leaving 3-1/4" protruding above the top. The hardwood top, shown in Pig. 4, was designed to be 3" x 18" x 24" and was built up in the carpenter shop. Hard pine two by four inch pieces were glued together and after- wards the whole piece was planed on the planer. Six 9/16" holes were drilled in this piece to correspond with the bolts in the conorete base. Two 1/2" holes were then drilled in the center to fasten the pum. A 1” hole was drilled to let the suction pipe down into the oil tank. fhe writers designed an oil tank with an open top, shown in Fig. 5, of No. 18 gauge galvanized iron. This was designed to fit on the inside of the hollow pum base. 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