scholarly journals Seismic Resistant Bridge Columns with NiTi Shape Memory Alloy and Ultra-High-Performance Concrete

2020 ◽  
Vol 5 (12) ◽  
pp. 105 ◽  
Author(s):  
Hadi Aryan
Keyword(s):  
Reinforced Concrete ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Performance ◽  
High Performance Concrete ◽  
Permanent Deformation ◽  
Bridge Columns ◽  
Ultra High Performance Concrete ◽  
Niti Sma ◽  
Column Design

Reinforced concrete bridge columns often endure significant damages during earthquakes due to the inherent deficiencies of conventional materials. Superior properties of the new materials such as shape memory alloy (SMA) and ultra-high-performance concrete (UHPC), compared to the reinforcing steel and the normal concrete, respectively, are needed to build a new generation of seismic resistant columns. Application of SMA or UHPC in columns has been separately studied, but this paper aims to combine the superelastic behavior of NiTi SMA and the high strength of UHPC, in order to produce a column design with minimum permanent deformation and high load tolerance subjected to strong ground motions. Additionally, the excellent corrosion resistance of NiTi SMA and the dense and impermeable microstructure of UHPC ensure the long-term durability of the proposed earthquake resistant column design. The seismic performance of four columns, defined as steel reinforced concrete (S-C), SMA reinforced concrete (SMA-C), SMA reinforced UHPC (SMA-UHPC), and reduced SMA reinforced UHPC (R-SMA-UHPC) is analyzed through a loading protocol with up to 4% drift cycles. The use of NiTi SMA bars for the SMA reinforced columns is limited to the plastic hinge region where permanent deformations happen. All the columns have 2.0% reinforcement ratio, except the R-SMA-UHPC column that has a 1.33% reinforcement ratio to optimize the use of SMA bars. Unlike the S-C column that showed up to 68% residual deformation compared to peak displacement during the last loading cycle the SMA reinforced columns did not experience permanent deformation. The SMA-C and R-SMA-UHPC columns showed similar strengths to the S-C column, but with about 5.0- and 6.5-times larger ductility, respectively. The SMA-UHPC column showed 30% higher strength and 7.5 times larger ductility compared to the S-C column.

scholarly journals UHPC Infilled Circular steel Tube Column Design

2021 ◽  
Author(s):  
Youssef Hilal
Keyword(s):  
Cross Section ◽  
High Performance ◽  
High Performance Concrete ◽  
Steel Tube ◽  
Design Code ◽  
Ultra High Performance Concrete ◽  
Steel Tubes ◽  
Design Strength ◽  
Circular Steel Tube ◽  
Column Design

Previous researchers studied the behavior of Ultra-High Performance Concrete (UHPC) columns confined with steel tubes. However, predicting the influence of the confinement effect and the compressive capacity of these columns has yet to be further examined. Currently, the Canadian design code limits for reinforced concrete do not reach the strength nor the strain produced by using UHPC. This project uses the Canadian design methods for a cross-section of UHPC to form a column interaction curve and compared it with six test specimens. The effects of steel tube confinement will also be examined. Additionally, the Eurocode 4 (EC4) method, which includes the strengths of UHPC and confinement of steel tube, was used to formulate another column interaction curve. The results show that the Canadian code severely underestimates the design strength of confined UHPC while the EC4 provides much more accurate results.

scholarly journals Embedded carbon fiber-reinforced polymer rod in reinforced concrete frame and ultra-high-performance concrete frame joints

2019 ◽  
Vol 11 (S1) ◽  
pp. 35-51
Author(s):  
Shahnaz Basim ◽  
Farzad Hejazi ◽  
Raizal Saifulnaz Bin Muhammad Rashid
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
High Performance ◽  
High Performance Concrete ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Ultra High Performance Concrete ◽  
Concrete Frame ◽  
Reinforced Polymer

AbstractBeam–column joints play an important role in providing lateral stiffness and integrity of frames during dynamic loading such as earthquake. In the high humidity areas, during functioning of the building cracks occur, which leads to the corrosion of the reinforcement due to the environmental exposures. Therefore, one of the main failures mechanism of building during an earthquake is caused by easily yielding of corroded steel reinforcement, which leads to reduce functionality of the frame joints in transferring the loads. This study proposed a new design to reinforce the beam-column joints with embedded carbon fiber-reinforced polymer (CFRP) rods, due to their extremely high strength and stiffness, along with the fact that they will not rust or corrode and very light weight. CFRP rods are used in reinforced concrete (RC) frame and ultra-high-performance concrete (UHPC) frame subjected to dynamic load. The prototype of the proposed design is constructed as frame with conventional concrete and frame with UHPC material to conduct experiments Test as well as numerical analysis to evaluate the performance of the proposed joints under dynamic loads. The results showed improvement in the performance of the frames reinforced with embedded CFRP in joints in terms of lateral load resistance capacity, ductility behaviour, overall stiffness, and failure mechanism.

scholarly journals Influence of Cracking on Oxygen Transport in UHPFRC Using Stainless Steel Sensors

2019 ◽  
Vol 10 (1) ◽  
pp. 239
Author(s):  
Ana Martínez-Ibernón ◽  
Marta Roig-Flores ◽  
Josep Lliso-Ferrando ◽  
Eduardo J. Mezquida-Alcaraz ◽  
Manuel Valcuende ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Oxygen Availability ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced ◽  
Ultra High Performance Concrete ◽  
Cracking Behavior

Reinforced concrete elements frequently suffer small cracks that are not relevant from the mechanical point of view, but they can be an entrance point for aggressive agents, such as oxygen, which could initiate the degradation processes. Fiber-Reinforced Concrete and especially Ultra High Performance Concrete increase the multi-cracking behavior, reducing the crack width and spacing. In this work, the oxygen availability of three types of concrete was compared at similar strain levels to evaluate the benefit of multi-cracking in the transport of oxygen. The types of concrete studied include traditional, High-Performance, and Ultra-High-Performance Fiber-Reinforced Concrete with and without nanofibers. To this purpose, reinforced concrete beams sized 150 × 100 × 750 mm3 were prepared with embedded stainless steel sensors that were located at three heights, which have also been validated through this work. These beams were pre-cracked in bending up to fixed strain levels. The results indicate that the sensors used were able to detect oxygen availability due to the presence of cracks and the detected differences between the studied concretes. Ultra High Performance Concrete in the cracked state displayed lower oxygen availability than the uncracked High Performance Concrete, demonstrating its potential higher durability, even when working in cracked state, thanks to the increased multi-cracking response.

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