Buckling of steel and Ni-Ti reinforcements in very high performance concrete (VHPC) elements

Abstract

h i g h l i g h t s 10 VPHC columns with steel reinforcements were tested to study bar buckling.2 VPHC and 2 HPC columns with Ni-Ti reinforcements were tested to study bar buckling.Columns with both Ni-Ti and steel reinforcements were compared.

Cyclic response of precast column-to-foundation connection using UHPC and Ni Ti SMA reinforcements in columns

“…When the test finished, it was soaked with water to observe the cracking pattern (Figure 11). in conventional steel bars [28]; the fact that the Ni-Ti SMA bars can high significant tensile and compressive strains; the fact that the bond strength between the polished Ni-Ti SMA bar and UHPC concrete reduced by more than 70%, or even more due to cyclic loads compared to the corrugated bars [64,65]. This last fact led the strain to distribute along the bar length between couplers, which prevent the strains of the bar from concentrating at the joint, which would lead to brittle tensile failure.…”

“…Its high fibre content and its bond to these fibres due to its high compressive strength confer reinforced concrete elements great ductility without having to increase the transverse reinforcement ratio [16,[18][19][20][21][22][23][24][25][26]. Furthermore, UHPC undergoes less damage than other concretes under equal conditions [22,27,28] and greater energy dissipation capacity [23]. This material is also being used in the precast construction field [27,29,30].…”

Design Recommendations for Columns Made of Ultra-High-Performance Concrete and NiTi SMA Bars

“…The high steel fiber content of UHPC confers great ductility on structural elements without increasing the transverse reinforcement ratio [25][26][27][28][29][30][31][32][33][34]. UHPC also undergoes less damage than other types of concrete under equal loading conditions [30,35,36] and has a greater capacity to dissipate energy [31,37].…”

Behaviour of retrofited precast UHPC and Ni-Ti SMA column-to-foundation connection with CFRP wrapping layers

“…Its cementitious matrix contains small metal fibres at a very high dosage rate of at least 1% by volume [15,17] which confers high ductility and reduces the need for transverse reinforcement [16,18,27,[19][20][21][22][23][24][25][26]. Its use in structures dissipates energy [28] and reduces concrete damage [18,29,30] as it delays spalling of the concrete cover and compression reinforcement buckling [11,12,30]. It has also been applied to precast construction [29,31,32].…”