Efek Dari Tegangan Awal Tulangan Tarik Dan Temperatur Tinggi Pada Retak Beton
Abstract: Strength of
Structure decreased due to fire exposure. This strengrth was affected by type and
depth of crack, heat variation and fire duration- The deeper the crack, the
higher the reduction of strength of the structure as a whole, because the
convection of heat arrived on the steel reinforcement faster than the
conduciion lhe steel yielded faster. This research was conducted by making 30
specimens of standard concrete cylinder with 150 mm diameter and 300 mm long
and 26 specimens of concrete cylinder with 60 mm diameter and 40O mm long. The
steel bar was anchored in the middle of the cross sec{ion of the later
cylinders. The bar dimension of ,l3 mm diameter was reduced to 10 mm in 100 mm
long, positioned at 150 mm from the concrete cylinder ends. ln this research
there were 2 kinds of concrete strength used, which is 22,5 MPa and 40 MPa. The
peripheral surface of 60 mm diameter of concrete cylinder was heated in the
electrical heater at various temperature up to 750 °C for 1,5 hours and pulled
axialty to certain stresses during heating. The research included concrele
modulus of elasticity, crack width due to heating, effect of.heating
temperature to the steel bar. The results indicate that static modulus of
elasticity (employing SNI formula) is 8-25 % higher than that using B.C CP 110.
By comparing the research results (obtained from stress-strain relationship
curve) it is indicate that static modulus of elasticity is 1G 25 % higher than
to the B.C CP110. Test results also indicate that concrete is vumerable to
crack under high temperature. The averages of 3 cracks of the concrete are
1,61, 0,64, 0,55 and 0,75 mm for 100%Pcr, 80 %Pcr, 60%Pcr and 40%Pcr
respectively for concrete compressive strength of 22,5 MPa, while such cracks
are 1,30, 1,24, 0,96 and 0,83 mm for 40MPa. The crack widths are above
allowable crack width for interior and exterior structures by 121,18% and
168,10% respectively tor 22,5 MPa concrete specimers and 170,83% and228,28%
respectively for 40 MPa concrete. The elongation of specimens of 100%Pcr
loading is sQnificant compared to below 100%Ps loading. Steel bar elongations
for 80o/oPcr, 607oPcr, 40%Pcr are 12,9%, 9,70%, 8,36% respectively tor 22,5 MPa
cornpared to 100% Pcr, while for 40MPa concrete this elongations are 96,87%
13,98% and 9,29% respectively.
Keywords: concrete, crack,
fire, steel, yield
Penulis: Buyung Army, Lismar
Rusli, Apwiddhal Apwiddhal
Kode Jurnal: jptsipildd060003
