Study Of Short-time Flexural Behavior For Glulam String Beams In Different Prestressed State

Glulam wood material has been widely used in modern wood structures. Prestressed glulam beams can take full advantage of glulam wood compressive strength, increase the span of glulam beams and thereby saving the cost of glulam beams, which can promote the development of the wood structure. Prestressed glulam string beam is a kind of beam which was presstressed by screwing the web member in the middle of beams. Currently, the research related to prestressed glulam string beam is limited to preliminary theoretical analysis and experimental research for selection of glulam wood material. While the tests of entire prestressed glulam string beams have not been carried out yet. The influence of prestressing bars’number and the prestressing value to this kind of beams has not been validated and the appropriate quantitative relationship was lacked. Finite element simulation analysis on prestressed glulam string beam has not been carried out and there also needs further study on how to properly build analytical models. For the problems mentioned above, following work have been carried out in this paper.Flexural tests have been carried out on 36 prestressed glulam string beams and 9 ordinary glulam beams. The influence of prestressing bars’number and the prestressing value to prestressed glulam string beams have been studied on the aspects of ultimate loads, failure modes, load - deflection curves and sectional strain curves. The results showed that:the more prestressing bars or the greater prestressing value, the greater the bending ultimate and the failure modes tend more to ductile failure. With the growth of prestressing bars’number, the bending stiffness gets larger. While the increase of prestressing value could make the deflections smaller by increasing the inverted arch. Compared with ordinary glulam beams, prestressed glulam string beam can save the use of wood and significantly reduce costs.ABAQUS finite element analysis was used in this paper to simulate the prestressed glulam string beams. The influence of prestressing bars’number and the prestressing value to prestressed glulam string beams have been analyzed. The results were compared with that from the tests and the deviation was analyzed.