1 Introduction
2 Experimental and FE Modeling Approach
2.1 Test Specimens and Variables
Specimen | Size (width × depth × length) | Fire exposure time period (min) | Load level (%) | Load (tonf) |
---|---|---|---|---|
CONT | 250 × 400 × 5000 (S series) | – | – | – |
P1-60 | 60 | 40 | 4.82 | |
P1-90 | 90 | 40 | 4.82 | |
P1-120 | 120 | 40 | 4.82 | |
P2-60 | 60 | 60 | 7.23 | |
P2-120 | 120 | 60 | 7.23 | |
P3-60 | 60 | 80 | 9.56 | |
P3-120 | 120 | 80 | 9.56 | |
MCONT | 300 × 500 × 5000 (M series) | 60 | – | – |
MP1-60 | 120 | 40 | 10.31 | |
LCONT | 350 × 650 × 5000 (L series) | 60 | – | – |
LP1-60 | 120 | 40 | 18.79 |
2.2 Materials
28-day compressive strength (MPa) | 28-day tensile strength (MPa) | W/C (%) | s/a (%) | Weight per unit volume (kg/m3) | ||||
---|---|---|---|---|---|---|---|---|
W | C | S | G | FA | ||||
25.08 | 2.98 | 53.4 | 49.8 | 83 | 155 | 913 | 914 | 1.86 |
Steel bar | Tensile strength (MPa) | Elastic modulus (GPa) |
---|---|---|
D19 | 448 | 205 |
2.3 Test Set Up and Data Measurement
2.3.1 Fire Test and Residual Strength Test
2.3.2 Data Measurement
2.4 FE Modeling Approach
3 Results
3.1 Results of Fire Test
Specimen | The highest temperature (°C) | Maximum deflection (mm) |
---|---|---|
CONT | – | – |
P1-60 | 239 | 19.4 |
P1-90 | 523.6 | 30.9 |
P1-120 | 528.9 | 28.2 |
P2-60 | 214.1 | 18.7 |
P2-120 | 568.8 | 79.4 |
P3-60 | 312.1 | 37.3 |
P3-120 | 663.2 | 93.1 |
MCONT | – | – |
MP1-60 | 352.0 | 19.1 |
LCONT | – | – |
LP1-60 | 272.5 | 9.1 |
3.2 Results of Residual Strength Test
3.2.1 Load Bearing Capacity
3.2.2 Initial Stiffness
Specimen | Stiffness (kN/mm) | Stiffness ratio |
---|---|---|
CONT | 5.85 | 1.00 |
P1-60 | 4.05 | 0.69 |
P1-90 | 3.38 | 0.58 |
P1-120 | 3.28 | 0.56 |
P2-60 | 3.69 | 0.63 |
P2-120 | 2.91 | 0.50 |
P3-60 | 3.36 | 0.57 |
P3-120 | 2.51 | 0.43 |
MCONT | 14.93 | 1.00 |
MP1-60 | 10.25 | 0.69 |
LCONT | 33.32 | 1.00 |
LP1-60 | 24.74 | 0.77 |
3.2.3 Ductility
Specimen | Yielding load of rebar (kN) | ∆y (mm) | Strain of yielding load of rebar | ∆u (mm) | Ductility index (μ∆) |
---|---|---|---|---|---|
CONT | 163.12 | 30.00 | 0.002382 | 216.20 | 7.21 |
P1-60 | 152.66 | 32.48 | 0.003019 | 154.23 | 4.75 |
P1-90 | 151.68 | 34.43 | 0.003483 | 135.35 | 3.93 |
P1-120 | 149.11 | 35.83 | 0.003488 | 127.56 | 3.56 |
P2-60 | 151.95 | 32.11 | 0.003454 | 127.86 | 3.98 |
P2-120 | 148.61 | 36.42 | 0.003504 | 115.82 | 3.18 |
P3-60 | 151.81 | 32.69 | 0.003499 | 118.74 | 3.63 |
P3-120 | 146.49 | 38.99 | 0.003536 | 97.78 | 2.51 |
MCONT | 331.80 | 25.00 | 0.002382 | 121.10 | 4.84 |
MP1-60 | 302.71 | 27.60 | 0.002520 | 89.20 | 3.23 |
LCONT | 685.51 | 32.00 | 0.002380 | 109.00 | 3.41 |
LP1-60 | 610.32 | 24.00 | 0.002954 | 68.40 | 2.85 |