scholarly journals Composite Behavior of RC-HPFRC Tension Members under Service Loads

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 47
Author(s):  
Carlos Zanuy ◽  
Pedro Javier Irache ◽  
Alejandro García-Sainz
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Fiber Reinforced Concrete ◽  
Strength Increase ◽  
Rc Structures ◽  
Tension Softening ◽  
Service Load ◽  
High Performance Fiber ◽  
Tension Members ◽  
Crack Widths

A significant increase of the use of high-performance fiber-reinforced concrete (HPFRC) to strengthen reinforced concrete structures (RC) has been noted for the past few years, thereby achieving composite RC-HPFRC elements. Such a technique tries to take advantage of the superior material properties of HPFRC in the ultimate and service load regimes. Many of the existing works on RC-HPFRC elements have focused on the strength increase at the ultimate load state and much less effort has been devoted to the serviceability response. The in-service performance of RC structures is governed by the behavior of the tension chord, which determines the crack pattern (crack widths are critical for durability) and deformations. The presence of HPFRC is supposed to improve serviceability due to its strain-hardening and tension-softening capacities. In this paper, the experimental analysis of composite RC-HPFRC tension members is dealt with. Specimens consisting of a RC tie strengthened with two 35 mm thick HPFRC layers have been subjected to loads in the service range so that the deformational and cracking response can be analyzed. The HPFRC has been a cement-based mortar with 3% volumetric amount of short straight steel fibers with a compressive and tensile strength of 144 MPa and 8.5 MPa, respectively. The experiments have shown that RC-HPFRC has higher stiffness, first cracking strength and reduced crack widths and deformations compared to companion unstrengthened RC. To understand the observed behavioral stages, the experimental results are compared with an analytical tension chord model, which is a simplified version of a previous general model by the authors consisting of 4 key points. In addition, the influence of time-dependent shrinkage has been included in the presented approach.

scholarly journals Impact Resisting Mechanisms of Shear-Critical Reinforced Concrete Beams Strengthened with High-Performance FRC

2020 ◽  
Vol 10 (9) ◽  
pp. 3154
Author(s):  
Carlos Zanuy ◽  
Gonzalo S.D. Ulzurrun
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Environmental Cost ◽  
Interface Debonding ◽  
Rc Beams ◽  
Rc Structures ◽  
High Performance Fiber ◽  
The Impact

Reinforced concrete (RC) structures typically present brittle failures by shear or punching under impact loading. High-performance fiber-reinforced concrete (HPFRC) has great potential due to its superior strength and energy absorption. The higher price and environmental cost of HPFRC compared to conventional RC can be effectively overcome by partially strengthening impact-sensitive RC members with HPFRC. To study the feasibility of this technique, HPFRC was applied as a tensile layer at the bottom of RC beams. Drop weight impact tests were carried out on beams with two values (35 and 55 mm) of HPFRC thickness, in addition to companion RC beams. Results show that the impact response can be divided into two stages: a first stage governed by local effects and shear plug formation at midspan, and a second stage governed by global beam behavior with formation of shear web cracks. A new resisting mechanism was observed for beams strengthened with HPFRC, as the strengthening layer worked similarly to a stress ribbon retaining the damaged RC and reducing fragmentation-induced debris. Such mechanism was fully achieved by the specimens with 35 mm HPFRC layer but was limited for the specimens with 55 mm HPFRC layer due to impact-induced interface debonding.

Influence of technological factors on the properties of ultra-high-performance fiber reinforced concrete

2020 ◽  
pp. 135-147
Author(s):  
Igor Chilin ◽  
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Technological Factors ◽  
High Performance Fiber

Приведены результаты исследований и выполнена оценка влияния технологических факторов на реологические свойства самоуплотняющихся сталефибробетонных смесей, определены кратковременные и длительные физико-механические и деформативные характеристики сверхвысокопрочного сталефибробетона, включая определение его фактической морозостойкости.

scholarly journals Resistance of an Optimized Ultra-High Performance Fiber Reinforced Concrete to Projectile Impact

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 63
Author(s):  
Anna L. Mina ◽  
Michael F. Petrou ◽  
Konstantinos G. Trezos
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Depth Of Penetration ◽  
Projectile Impact ◽  
High Performance Fiber

The scope of this paper is to investigate the performance of ultra-high performance fiber reinforced concrete (UHPFRC) concrete slabs, under projectile impact. Mixture performance under impact loading was examined using bullets with 7.62 mm diameter and initial velocity 800 m/s. The UHPFRC, used in this study, consists of a combination of steel fibers of two lengths: 6 mm and 13 mm with the same diameter of 0.16 mm. Six composition mixtures were tested, four UHPFRC, one ultra-high performance concrete (UHPC), without steel fibers, and high strength concrete (HSC). Slabs with thicknesses of 15, 30, 50, and 70 mm were produced and subjected to real shotgun fire in the field. Penetration depth, material volume loss, and crater diameter were measured and analyzed. The test results show that the mixture with a combination of 3% 6 mm and 3% of 13 mm length of steel fibers exhibited the best resistance to projectile impact and only the slabs with 15 mm thickness had perforation. Empirical models that predict the depth of penetration were compared with the experimental results. This material can be used as an overlay to buildings or to construct small precast structures.

Direct tension-dependent flexural behavior of ultra-high-performance fiber-reinforced concretes

2017 ◽  
Vol 52 (2) ◽  
pp. 121-134 ◽  
Author(s):  
Duy-Liem Nguyen ◽  
Duc-Kien Thai ◽  
Dong-Joo Kim
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Tensile Strain ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Tensile Response ◽  
High Performance Fiber ◽  
The Moment ◽  
Direct Tensile ◽  
Flexural Resistance

This research investigated the effects of direct tensile response on the flexural resistance of ultra-high-performance fiber-reinforced concretes by performing sectional analysis. The correlations between direct tensile and flexural response of ultra-high-performance fiber-reinforced concretes were investigated in detail for the development of a design code of ultra-high-performance fiber-reinforced concrete flexural members as follows: (1) the tensile resistance of ultra-high-performance fiber-reinforced concretes right after first-cracking in tension should be higher than one-third of the first-cracking strength to obtain the deflection-hardening if the ultra-high-performance fiber-reinforced concretes show tensile strain-softening response; (2) the equivalent bottom strain of flexural member at the modulus of rupture is always higher than the strain capacity of ultra-high-performance fiber-reinforced concretes in tension; (3) the softening part in the direct tensile response of ultra-high-performance fiber-reinforced concretes significantly affects their flexural resistance; and (4) the moment resistance of ultra-high-performance fiber-reinforced concrete girders is more significantly influenced by the post-cracking tensile strength rather than the tensile strain capacity. Moreover, the size and geometry effects should be carefully considered in predicting the moment capacity of ultra-high-performance fiber-reinforced concrete beams.

Sign in / Sign up

Export Citation Format

Share Document