The effect of dimensional changes of flange and web in I-joist on its bending strength

Document Type : Research Paper

Authors

1 Associate prof., Department of bio-systems, Faculty of new technologies engineering, Shahid Beheshti university, Tehran, Iran

2 MS.C., Department of wood and paper science and technology, Faculty of natural resources, University of Zabol, Zabol, Iran

3 Associate prof., Department of wood and paper science and technology, Faculty of natural resources, University of Zabol, Zabol, Iran

Abstract

This study evaluated the effects of flange thickness to depth of web ratio at three levels (1:2, 1.5:3.5 and 2:5) as well as thickness to depth of web ratio at three levels (0.5:2, 0.5:3.5 and 0.5:5) and width of flange at three levels (3, 3.8 and 4.6 cm) as independent variables on some mechanical properties e.g. modulus of rupture (MOR) and modulus of elasticity (MOE) of I-joist manufactured from ash wood (Fraxinus sp.). For this purpose, response surface methodology (RSM) was applied to evaluate the effects of independent variables on MOR and MOE of I-joist based on a three-level, three-variable central composite rotatable design (CCRD). In this survey, bending test was done according to the ASTM D-5055. Mathematical model equations were derived from computer simulation programing to find significant differences and the most effective variables. According to the results, predicted values were found to be in agreement with actual values (R2 values of 0.99 and 0.98 for MOR and MOE, respectively). The study showed that RSM can efficiently be applied in modeling bending properties of I-joist. It was found that all independent variables had direct effect and significant effect on responces; in a way that flange thickness to depth of web ratio, thickness to depth of beam web ratio and width of flange maintained the MOR and MOE at maximum levels up to 2:5, 0.5:5 and 4.6cm, respectively. Simultaneously, some quadratic and interaction terms of variables had significant effects, too. Generally, increment in flange thickness to depth of web ratio, thickness to depth of web ratio and width of flange increased MOR and MOE of I-joist. Besides, flange thickness to depth of web ratio had the strongest effect on bending strength of beams

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References

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Iranian Journal of Wood and Paper Industries
Volume 10, Issue 4
February 2020
Pages 507-520

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