Experimental Study About Dynamic Properties Of Modern Bamboo Structure

There are a considerable number of static tests on modern bamboo structures; however, researches on their dynamic performance are relatively few, which leaves a lot of room for further studies. The following two aspects of modern bamboo structures performance are taken into account.In practical engineering, the structure has to carry both static and repeated dynamic loads, such as bridges, crane beams, etc. Researches on the structure’s capacity to carry repeated loads involve the fatigue performance of the structure. The vertical vibration of modern wooden floors, which affects the comfort index of occupants, has plagued people for a long time. Since modern bamboo structures and wooden structures have something in common in terms of building materials and structural mode, the question whether it is comfortable living on bamboo floors is proposed as the target of our study.From the perspective on testing the dynamic performance of modern bamboo structures, the main research contents are as follows:Firstly, six laminated bamboo beams of the same size and finger-jointed location are designed, with three of them as tested beams and the other three as compared ones, and then fatigue tests are conducted as well as static damage tests on them respectively. When the fatigue tests are conducted to a predetermined number of times, stop them for static loading tests concerning beam load-deflection curves and strain distribution. The results show that laminated bamboo beams have fairly good fatigue resistance and enjoy a fatigue life of more than two million times. Stiffness of laminated bamboo beams in the fatigue process show a decline-smooth trend and stiffness decline is relatively greater in the initial stage of fatigue. But in general, there is no obvious decrease in the stiffness of the beams but we observe a decline in their strength with a decreased limit bearing capacity by 15%.Secondly, the identification method of bamboo beams’damage by modal testing is researched. At different stages of the fatigue test, the bamboo beams are vibrated by hammering, and the acceleration response is collected. Then, the modal parameters of bamboo beams at different fatigue stages are calculated by using the new PolyMax method, and the results are analysised. The results show that it can obtain the modal parameters of bamboo beams preferably by hammering them. But, the fundamental frequency isn’t sensitive to the damage, so it shouldn’t be the target of damage detection.Finally, the comfortable level of a bamboo structure floor is evaluated. Reference to the test methods of modern wood structure, reinforced concrete structure, etc, the writer evaluate the comfortable level of a bamboo structure floor by testing the static deflection, the fundamental frequency and peak acceleration. The results show that these three targets of the floor are consistent with the international norms, and the testing floor is comfortable enough.