پديد آورندگان :
ناظريان مرتضي داﻧﺸﮕﺎه ﺷﻬﯿﺪ ﺑﻬﺸﺘﯽ - داﻧﺸﮑﺪه ﻣﻬﻨﺪﺳﯽ ﻓﻨﺎوريﻫﺎي ﻧﻮﯾﻦ - گروه سامانه هاي زيستي , رضائيان عليرضا داﻧﺸﮕﺎه زاﺑﻞ - داﻧﺸﮑﺪه ﻣﻨﺎﺑﻊ ﻃﺒﯿﻌﯽ - ﮔﺮوه ﺻﻨﺎﯾﻊ ﭼﻮب و ﻓﺮاورده ﻫﺎي ﺳﻠﻮﻟﺰي , شمسيان محمد داﻧﺸﮕﺎه زاﺑﻞ - داﻧﺸﮑﺪه ﻣﻨﺎﺑﻊ ﻃﺒﯿﻌﯽ - ﮔﺮوه ﺻﻨﺎﯾﻊ ﭼﻮب و ﻓﺮاورده ﻫﺎي ﺳﻠﻮﻟﺰي
چكيده فارسي :
اﯾﻦ ﺑﺮرﺳﯽ اﺛﺮات ﻧﺴﺒﺖ ﺿﺨﺎﻣﺖ ﺑﺎل ﺑﻪ ارﺗﻔﺎع ﺟﺎن در ﺳﻪ ﺳﻄﺢ )1/5 :3/5 ،1:2 و 2 :5(، ﻫﻤﯿﻨﻄﻮر ﻧﺴﺒﺖ ﺿﺨﺎﻣﺖ ﺑﻪ ارﺗﻔﺎع ﺟﺎن در ﺳﻪ ﺳﻄﺢ )0/5 :3/5 ،0/5 :2، و 5: 0/5( و ﻋﺮض ﺑﺎل در ﺳﻪ ﺳﻄﺢ )3/8 ،3 و 4/6 ﺳﺎﻧﺘﯿﻤﺘﺮ( ﺑﻪ ﻋﻨﻮان ﻣﺘﻐﯿﺮﻫﺎي ﻣﺴﺘﻘﻞ ﺑﺮ روي ﺑﻌﻀﯽ از ﺧﻮاص ﻣﮑﺎﻧﯿﮑﯽ ﻧﻈﯿﺮ ﻣﺪول ﮔﺴﯿﺨﺘﮕﯽ )MOR( و ﻣﺪول اﻻﺳﺘﯿﺴﯿﺘﻪ )MOE( ﺗﯿﺮﻫﺎي I ﺷﮑﻞ ﺳﺎﺧﺘﻪ ﺷﺪه از ﭼﻮب زﺑﺎن ﮔﻨﺠﺸﮏ ).Fraxinus spp( را ارزﯾﺎﺑﯽ ﮐﺮده اﺳﺖ. ﺑﺮاي اﯾﻦ ﻣﻨﻈﻮر، روش ﺳﻄﺢ ﭘﺎﺳﺦ )RSM( ﺑﺮاي ارزﯾﺎﺑﯽ اﺛﺮات ﻣﺘﻐﯿﺮﻫﺎي ﻣﺴﺘﻘﻞ ﺑﺮ روي MOR و MOE ﺗﯿﺮﻫﺎي I ﺷﮑﻞ ﺑﺮ اﺳﺎس ﻃﺮح ﻣﺤﻮر ﭼﺮﺧﺸﯽ ﻣﺮﮐﺐ ﻣﺮﮐﺰي )CCRD( ﺑﺎ ﺳﻪ ﻣﺘﻐﯿﺮ و ﺳﻪ ﺳﻄﺢ ﻣﻮرد اﺳﺘﻔﺎده ﻗﺮار ﮔﺮﻓﺖ. در اﯾﻦ ارزﯾﺎﺑﯽ، آزﻣﻮن ﺧﻤﺶ ﻣﻄﺎﺑﻖ اﺳﺘﺎﻧﺪارد 5055-ASTM D اﻧﺠﺎم ﭘﺬﯾﺮﻓﺖ. ﻣﻌﺎدﻟﻪﻫﺎي ﻣﺪل رﯾﺎﺿﯽ ﺗﻮﺳﻂ ﺑﻬﺮهﮔﯿﺮي از ﺑﺮﻧﺎﻣﻪ ﺷﺒﯿﻪﺳﺎز ﮐﺎﻣﭙﯿﻮﺗﺮي ﺑﻪ ﻣﻨﻈﻮر ﯾﺎﻓﺘﻦ اﺧﺘﻼفﻫﺎي ﻣﻌﻨﯽدار و ﺗﺎﺛﯿﺮﮔﺬارﺗﺮﯾﻦ ﻣﺘﻐﯿﺮﻫﺎ ﺑﺪﺳﺖ آﻣﺪ. ﺑﺮ اﺳﺎس ﻧﺘﺎﯾﺞ، ﻣﻘﺎدﯾﺮ ﭘﯿﺶﺑﯿﻨﯽ ﺷﺪه در ﺗﻄﺎﺑﻖ ﺑﺎ ﻣﻘﺎدﯾﺮ ﺑﺪﺳﺖ آﻣﺪه ﺑﻮدهاﻧﺪ )ﻣﻘﺪار R2 ﺑﺮاي MOR و MOE ﺑﻪ ﺗﺮﺗﯿﺐ ﺑﺮاﺑﺮ 0/99 و 0/98(. ﺑﺮرﺳﯽ ﻧﺸﺎن داد ﮐﻪ RSM ﻣﯽﺗﻮاﻧﺪ ﺑﻪﻃﻮر ﻣﻮﺛﺮي در ﻣﺪلﺳﺎزي ﺧﻮاص ﺧﻤﺸﯽ ﺗﯿﺮ I ﺷﮑﻞ ﻣﻮرد اﺳﺘﻔﺎده ﻗﺮار ﮔﯿﺮد. ﻣﻌﻠﻮم ﮔﺮدﯾﺪ ﮐﻪ ﻫﻤﻪ ﻣﺘﻐﯿﺮﻫﺎي ﻣﺴﺘﻘﻞ اﺛﺮ ﻣﺴﺘﻘﯿﻢ و ﻣﻌﻨﯽدار ﺑﺮ روي ﭘﺎﺳﺦﻫﺎ داﺷﺘﻪاﻧﺪ، ﺑﻨﺤﻮي ﮐﻪ ﻧﺴﺒﺖ ﺿﺨﺎﻣﺖ ﺑﺎل ﺑﻪ ارﺗﻔﺎع ﺟﺎن، ﻧﺴﺴﺒﺖ ﺿﺨﺎﻣﺖ ﺑﻪ ارﺗﻔﺎع ﺗﯿﺮ و ﻋﺮض ﺑﺎل در ﺳﻄﻮح ﺑﻪ ﺗﺮﺗﯿﺐ ﺑﺮاﺑﺮ ﺑﺎ 2:5، 0/5 :5 و cm 4/6 ﻣﻘﺎدﯾﺮ MOR و MOE را در ﺣﺪاﮐﺜﺮ ﻣﯿﺰان ﻗﺮار دادﻧﺪ. ﻫﻤﺰﻣﺎن، ﺑﻌﻀﯽ از اﺛﺮات ﻣﺘﻘﺎﺑﻞ و ﻣﺮﺑﻊ اﺛﺮات ﻣﺘﻐﯿﺮﻫﺎ ﻧﯿﺰ ﺗﺎﺛﯿﺮات ﻣﻌﻨﯽداري داﺷﺘﻪاﻧﺪ. ﺑﻄﻮر ﮐﻠﯽ، اﻓﺰاﯾﺶ در ﻧﺴﺒﺖ ﺿﺨﺎﻣﺖ ﺑﺎل ﺑﻪ ارﺗﻔﺎع، ﻧﺴﺒﺖ ﺿﺨﺎﻣﺖ ﺑﻪ ارﺗﻔﺎع ﺟﺎن و ﻋﺮض ﺑﺎل MOR و MOE ﺗﯿﺮﻫﺎي I ﺷﮑﻞ را اﻓﺰاﯾﺶ داد. ﻋﻼوه ﺑﺮ آن، ﻧﺴﺒﺖ ﺿﺨﺎﻣﺖ ﺑﺎل ﺑﻪ ارﺗﻔﺎع ﺟﺎن ﺑﯿﺸﺘﺮﯾﻦ ﺗﺎﺛﯿﺮ را ﺑﺮ روي ﻣﻘﺎوﻣﺖ ﺧﻤﺸﯽ ﺗﯿﺮ داﺷﺖ.
چكيده لاتين :
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
