PERBANDINGAN KEKUATAN JEMBATAN RANGKA TIPE PRATT, PARKER, DAN BROWSTRING DALAM MENERIMA BEBAN YANG SAMA DAN HASIL PENERAPANNYA PADA MATERIAL BAMBU

Abstract

Based on the fact, the further research is conducted to compare the strength of three types truss bridge with bamboo material, the type are Pratt, Parker, and Bowstring. On the laboratory test results obtained that values of tensile strength and compressive strength average are 683.7918 Kg/cm2 and 391 801 Kg/cm2, then bamboo safety factor obtained from ISO is 2.25 and the resulting value of allowable tensile stress and allowable compressive stress are 303.9075 kg / cm2 and 174.134 kg/cm2. The third type of truss bridge with a span of 20 meters, a width of 5 meters and high of 4 meters will support the same load that is placed in the middle of the span such as 1 ton, 2 tons, 3 tons and 4 tons. Then the load simulation is using structural analysis programs. It found that Pratt truss is the strongest truss bridge because has a maximum value of smallest axial force and smallest deflection between Parker and Bowstring truss. After obtained the forces in structure analysis program then search for the value of the maximum stress occurs in the truss and compared with the stress at laboraturium and the results for the value of deflection on the analysis program structure is 0.024622 m, this value is smaller and still be under permit deflection value of 0.025 m. For the maximum tensile stress value in structural analysis program is 139 442 kg / cm 2, the value is 54.12% lower than the results of the average collapse stress during testing is 303.9075 kg / cm2. While for the maximum compressive stress on structural analysis program obtained from 219 688 kg / cm 2, the valueis 26.16% bigger than the results of the average compressive stress during testing in laboraturium was 174.134 kg / cm 2 so, when the bridge was given a load over 4 tons, the truss can not support the axial force.