Experimental and numerical studies of inelastic behavior of thin walled elbow and tee joint under seismic load

In the present work, experimental and numerical studies are carried out on inelastic behavior of thin walled elbow and tee joint under incremental seismic load, with an emphasis on fatigue-ratcheting. Initially, a short radius carbon steel (SA106 Gr B) elbow is subjected to internal pressure and incremental seismic excitation till failure. The tested elbow is analyzed using a simplified method to evaluate ratcheting and compared with test results. Simulations are carried out with uniform and actual thickness distribution to study the variation in strain accumulation. Later, a tee joint of same material and size is studied under similar loading conditions till failure. The resulting strain accumulation in elbow and tee joint are compared. The change in natural frequencies of elbow and tee during the test are evaluated using wavelet analysis and the details are provided in the paper.