ﺑﺮرﺳﯽ رﻓﺘﺎر ﭘﯿﭽﺸﯽ ﺑﺘﻦ ﺧﻮدﺗﺮاﮐﻢ اﻟﯿﺎﻓﯽ ﺗﺤﺖ ﺑﺎرﻫﺎي ﺳﯿﮑﻠﯽ

Investigating Torsional Behavior of Fiber Reinforced Self Consolidating Concrete under Cyclic Loading

ﺧﺼﻮﺻﯿﺎت ﺑﺘﻦ ﺧﻮدﺗﺮاﮐﻢ اﻟﯿﺎﻓﯽ ﺗﺎزه و ﺳﺨﺖ ﺷﺪه ﻣﻮرد ﺗﻮﺟﻪ ﻣﺤﻘﻘﯿﻦ در ﺻﻨﻌﺖ ﺳﺎﺧﺖ و ﺳﺎز ﻣﯽﺑﺎﺷﺪ وﻟﯿﮑﻦ، رﻓﺘﺎر اﯾﻦ ﺑﺘﻦ ﺗﺤﺖ اﺛﺮ ﭘﯿﭽﺶ ﻣﺘﻨﺎوب، ﻧﺎﺷﯽ از اﻋﻤﺎل ﺑﺎرﻫﺎي ﺳﯿﮑﻠﯽ ﮐﻤﺘﺮ ﻣﻮرد ﺑﺮرﺳﯽ ﻣﺤﻘﻘﺎن ﻗﺮار ﮔﺮﻓﺘﻪ اﺳﺖ. در اﯾﻦ ﭘﮋوﻫﺶ آزﻣﺎﯾﺸﮕﺎﻫﯽ رﻓﺘﺎر ﺑﺘﻦ ﺧﻮدﺗﺮاﮐﻢ اﻟﯿﺎﻓﯽ ﺗﺤﺖ اﺛﺮ ﭘﯿﭽﺶ ﺳﯿﮑﻠﯽ ﻣﻄﺎﻟﻌﻪ ﺷﺪ. ﺟﻬﺖ اﻋﻤﺎل ﭘﯿﭽﺶ، ﻧﻤﻮﻧﻪﻫﺎي T ﺷﮑﻞ ﺳﺎﺧﺘﻪ ﺷﺪ ﮐﻪ ﺑﻪ ﺻﻮرت واروﻧﻪ در دو اﻧﺘﻬﺎي ﻗﺴﻤﺖ اﻓﻘﯽ ﺑﻪ ﺻﻮرت ﮔﯿﺮدار روي ﺗﮑﯿﻪ ﮔﺎه ﻣﺘﺼﻞ ﺑﻪ ﮐﻒ ﺻﻠﺐ ﻗﺮار ﮔﺮﻓﺖ و ﺗﻮﺳﻂ دﺳﺘﮕﺎه اﮐﭽﻮﯾﯿﺘﻮر ﻧﯿﺮوي رﻓﺖ و ﺑﺮﮔﺸﺘﯽ ﺑﺎ داﻣﻨﻪﻫﺎي ﻣﺘﻔﺎوت ﺑﻪ اﻧﺘﻬﺎي ﻗﺴﻤﺖ ﻋﻤﻮدي وارد ﺷﺪ ﺗﺎ ﻗﺴﻤﺖ اﻓﻘﯽ ﺣﻮل ﻣﺤﻮر ﻃﻮﻟﯽاش ﺗﺤﺖ ﭘﯿﭽﺶ ﻗﺮار ﮔﯿﺮد. ﻗﺴﻤﺖ ﻋﻤﻮدي ﻧﻤﻮﻧﻪ ﺣﺎوي ﺑﺘﻦ ﺑﺪون اﻟﯿﺎف ﺗﻮﺳﻂ ﻣﯿﻠﮕﺮدﻫﺎي ﻃﻮﻟﯽ و ﻋﺮﺿﯽ ﻣﺴﻠﺢ ﺷﺪ ﺑﻪ ﻃﻮريﮐﻪ، در زﻣﺎن اﻋﻤﺎل ﺑﺎر ﺟﺎري ﻧﺸﻮﻧﺪ و از ﻃﺮﯾﻖ آن ﭘﯿﭽﺶ ﺑﻪ ﻗﺴﻤﺖ اﻓﻘﯽ ﺳﺎﺧﺘﻪ ﺷﺪه ﺑﺎ ﺑﺘﻦ ﺧﻮدﺗﺮاﮐﻢ اﻟﯿﺎﻓﯽ وارد ﺷﻮد. ﺑﺎ ﻧﯿﺮوي اﻋﻤﺎل ﺷﺪه و ﺗﺮﺳﯿﻢ ﻧﻤﻮدارﻫﺎي ﻫﯿﺴﺘﺮﺳﯿﺲ، ﻣﯿﺰان ﺗﺤﻤﻞ ﻟﻨﮕﺮ ﭘﯿﭽﺸﯽ و اﺗﻼف اﻧﺮژي ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺖ. از ﺑﺘﻦ ﺧﻮدﺗﺮاﮐﻢ رده C50 و اﻟﯿﺎف ﻓﻮﻻدي ﺑﺎ اﻧﺘﻬﺎي ﻗﻼبدار و ﻧﺴﺒﺖ ﻃﻮل ﺑﻪ ﻗﻄﺮ 62/5 ﺑﻪ ﻣﯿﺰان ﺻﻔﺮ )ﺑﺘﻦ ﺷﺎﻫﺪ(، 0/5 ،0/25و 0/75 درﺻﺪ ﺣﺠﻢ ﺑﺘﻦ اﺳﺘﻔﺎده ﺷﺪ. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻧﺘﺎﯾﺞ ﺑﻪ دﺳﺖ آﻣﺪه ﻣﯿﺰان 0/5 درﺻﺪ اﻟﯿﺎف در ﺗﻤﺎﻣﯽ آزﻣﺎﯾﺶﻫﺎ داراي ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان اﺗﻼف اﻧﺮژي ﺗﺎ3/87 و ﺑﯿﺸﺘﺮﯾﻦ ﻟﻨﮕﺮ ﭘﯿﭽﺸﯽ ﺗﺎ2/46 ﺑﺮاﺑﺮ ﻧﻤﻮﻧﻪ ﺷﺎﻫﺪ داﺷﺘﻪ اﺳﺖ.

Researchers in the construction industry have shown great interest in rheological and mechanical properties as well as durability of fiber reinforced self-compacting concrete (FRSCC), however, its behavior under torsional cyclic loading, has rarely been studied. In the present experimental research, behavior of fiber reinforced self-compacting concrete under cyclic torsional loading was studied. T-shaped samples consisting of a horizontal beam made of FRSCC and a vertical shaft were made. Horizontal beam was fixed at both ends to a rigid base and cyclic loading was applied to the end of the vertical shaft causing a cyclic torque around the horizontal axis of the beam. The vertical shaft was reinforced by longitudinal and transverse bars so that it could not collapse at the time of loading. By plotting the hysteresis diagrams, the torsional strength and energy dissipation of each sample specimen were investigated. Self-compacting concrete C50 class and Hooked End Steel Fibers with length to diameter ratio of 62.5 and different amount of 0, 0.25, 0.5 and 0.75 percent by volume were used. Results showed that the mixture containing 0.5% fibers had the highest energy dissipation of 3.87 times that of control mix with no fibers, and maximum torsional strength of 2.46 times that of control mix.