Active action of prestressing on direct tensile behavior of mortar reinforced with NiTi SMA crimped fibers

2021 ◽  
pp. 115119
Author(s):  
Eunsoo Choi ◽  
Jong-Su Jeon ◽  
Jong-Han Lee
Keyword(s):  
Tensile Behavior ◽  
Niti Sma ◽  
Direct Tensile

scholarly journals Active Reinforcing Fiber of Cementitious Materials Using Crimped NiTi SMA Fiber for Crack-Bridging and Pullout Resistance

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3845
Author(s):  
Eunsoo Choi ◽  
Ha Vinh Ho ◽  
Jong-Su Jeon
Keyword(s):  
Residual Stress ◽  
Flexural Rigidity ◽  
Large Diameter ◽  
Cold Drawing ◽  
Cementitious Materials ◽  
Tensile Behavior ◽  
Recovery Stress ◽  
Pullout Resistance ◽  
Niti Sma ◽  
Straight Fiber

This study investigated the recovery stress and bond resistance of cold drawn crimped SMA fiber using two different initial diameters of 1.0 and 0.7 mm. These characteristics are important to the active prestressing effect and crack-closing of the fiber. NiTi SMA fiber was used for the cold drawing, and then crimped shapes were manufactured with various wave heights. After that, tensile, recovery, and pullout tests were conducted. The cold drawn crimped fiber showed softening tensile behavior more clearly than the cold drawn straight fiber when not subjected to heating, whereas they had the same tensile behavior under heating. The recovery stress and the residual stress of the crimped fibers were less than those of the straight fiber with the same diameter. Moreover, crimped fibers with a large diameter and higher wave height would induce more recovery stress and residual stress. The maximum pullout resistance of the crimped fiber was a function of the wave depth, embedded length, yield strength, and flexural rigidity of the fiber.

Evaluation of the Direct Tensile Behavioral Characteristics of UHPC Using Twisted Steel Fibers

2012 ◽  
Vol 602-604 ◽  
pp. 96-101 ◽  
Author(s):  
Gum Sung Ryu ◽  
Si Hwan Kim ◽  
Gi Hong Ahn ◽  
Kyung Taek Koh
Keyword(s):  
Small Proportion ◽  
Mechanical Characteristics ◽  
Steel Fiber ◽  
Tensile Behavior ◽  
Steel Fibers ◽  
Superior Performance ◽  
Behavioral Characteristics ◽  
Straight Fiber ◽  
Direct Tensile ◽  
Twisted Fiber

This paper investigates the improvement of the toughness of UHPC through the use of conventional straight steel fibers and twisted fibers. The conventional straight steel fiber has length of 13 mm and diameter of 0.2 mm. Besides, twisted fibers with diameters of 0.2 mm, 0.22 mm and 0.3 mm, respective lengths of 20 mm, 22 mm and 30 mm and made of high elastic steel fibers with aspect ratio (l/d) of 100 are used at volume fractions of 1%, 1.5% and 2%. The results of the examination of the direct tensile behavior reveal the occurrence of strain hardening after early cracking. K-UHPC using twisted fiber exhibits significantly improved mechanical characteristics compared to UHPC using conventional straight fiber. Equivalent or superior performance is developed when small proportion of about 0.5% of steel fiber is adopted and 90% of the performance is developed when small proportion of approximately 1.0% of fiber is admixed. Consequently, the use of twisted fiber in K-UHPC opens the possibility to achieve economically efficient fabrication by enabling significant reduction of the amount of fiber.

Direct Tensile Behavior of Limestone and Sandstone with Bedding Planes at Different Strain Rates

2020 ◽  
Vol 53 (6) ◽  
pp. 2643-2651 ◽  
Author(s):  
Duofeng Cen ◽  
Da Huang ◽  
Yixiang Song ◽  
Qinghui Jiang
Keyword(s):  
Tensile Behavior ◽  
Strain Rates ◽  
Bedding Planes ◽  
Direct Tensile

Influence of Hybrid Steel Fiber Addition on Direct Tensile Behavior of UHPC

2016 ◽  
Vol 713 ◽  
pp. 270-272
Author(s):  
Seung Hun Park ◽  
Kyung Taek Koh ◽  
Gum Sung Ryu ◽  
Gi Hong An ◽  
Nam Kon Lee
Keyword(s):  
High Performance ◽  
Steel Fiber ◽  
Absorption Capacity ◽  
Tensile Behavior ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Energy Absorption Capacity ◽  
High Performance Fiber ◽  
Direct Tensile ◽  
Direct Tensile Test

This paper examines the direct tensile behavior of ultra high performance fiber reinforced concrete (UHPFRC) according to the addition of hybrid-type steel fibers with different lengths and diameters but identical aspect ratio. Two types of steel fibers that are MS fiber with length of 20 mm and diameter of 0.2 mm and LS fiber with length of 22 mm and diameter of 0.22 mm are adopted and admixed together with different proportions to give three series of mixes (MS10LS05, MS075LS075, MS05LS10). Direct tensile test is conducted on specimens using each of the considered mixes and notched on both sides. The results show that the tensile strength and the energy absorption capacity of UHPFRC tend to increase with larger proportions of relatively long steel fibers.

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