Effect of Crack on Interfacial Stresses of RC Beam Strengthened with CFRP

2011 ◽  
Vol 462-463 ◽  
pp. 559-562
Author(s):  
Yong Chang Guo ◽  
Han Lin Huang ◽  
Li Juan Li ◽  
Jun Deng ◽  
Gen Quan Zhong
Keyword(s):  
Failure Modes ◽  
Weight Ratio ◽  
Adhesive Layer ◽  
High Strength ◽  
Tensile Failure ◽  
Interface Debonding ◽  
Rc Beam ◽  
Longitudinal Stress ◽  
Interfacial Stresses ◽  
Rc Structures

External bonding of fiber reinforced polymer (FRP) plates or sheets, because of their advantages, such as high strength to weight ratio and good resistance to corrosion, has become a popular technique for the strengthening and upgrading of structurally inadequate or damaged reinforced concrete (RC) structures. Interface debonding failure is one of the most common failure modes of the FRP strengthened RC structures. In this paper, the damaged concrete constitutive model is established and the effects of crack on the interfacial stresses of RC beam strengthened with CFRP are investigated. Longitudinal stress in the CFRP, shear stress in the adhesive layer and the first principal stress in the concrete at the crack tips of the retrofitted RC beams with cracks at different locations are analyzed. The results show that when cracks locate at the loading position, the longitudinal stress in the CFRP is the largest and the tensile failure of the CFRP is the most likely occurred.

C-section Cold-Formed Steel as Structural Members in Housing Construction in the Philippines

2019 ◽  
Author(s):  
Bernardo A. Lejano
Keyword(s):  
Axial Compression ◽  
High Speed ◽  
Failure Modes ◽  
Weight Ratio ◽  
High Strength ◽  
The Philippines ◽  
Bending Test ◽  
Housing Construction ◽  
Distortional Buckling ◽  
Cold Formed Steel

<p>Getting good lumber for housing construction is becoming difficult in the Philippines due to existing partial log ban. Although, the use of reinforced concrete is still the most popular in construction, an emerging alternative is the use of cold-formed steel (CFS). It is gaining popularity because of its high strength-to- weight ratio. However, information about the structural performance of locally-produced cold-formed steel is almost nonexistent. Although, design provisions are stipulated in the local Code, these are based on formulas developed abroad, hence the need to investigate these cold-formed steel. This study focuses on the C-section cold-formed steel, which is the most popularly used. The objective is to verify its performance when subjected to axial compression and flexure, both experimentally and computationally. For the computational part, the formulas stipulated in the National Structural Code of the Philippines were followed. For the experimental part, the cold-formed steel members were subjected to compression loads and flexural loads. Aside from usual sensors, high-speed cameras were used to capture the failure modes. For axial compression test, 80 specimens with different lengths and thicknesses were tested. For flexure, 24 specimens of back-to-back C-sections were subjected to 4-point bending test. Results showed the predicted strengths were well below the experimental values. In design, this means the use of Code-based formulas is conservative. Failure modes observed were torsional buckling and distortional buckling. Comparison of failure modes between experiment and computation shows 70% agreement for compression and 75% for flexure. Finite element method calculations were also done and were compared with experimental results.</p>

Experimental and Numerical Researches of Dynamic Failure of a High Strength Alumina/Boride Ceramic Composite

2008 ◽  
Vol 368-372 ◽  
pp. 713-716 ◽  
Author(s):  
Jiang Tao Zhang ◽  
Li Sheng Liu ◽  
Peng Cheng Zhai ◽  
Qing Jie Zhang
Keyword(s):  
Ceramic Composite ◽  
Failure Modes ◽  
Split Hopkinson Pressure Bar ◽  
Numerical Models ◽  
High Strength ◽  
Tensile Failure ◽  
Hopkinson Pressure Bar ◽  
Loading Direction ◽  
Split Hopkinson ◽  
Pressure Bar

The dynamic compressive behavior of Al2O3 (10% vol.) / TiB2 ceramic composite had been tested by using a split Hopkinson pressure bar in this paper. The results show that the main failure modes of the ceramic composite include crushed failure and split fracture along the loading direction. The former is the typical compressive failure of brittle materials. The later is tensile failure along the flaws produced during the composite manufacturing. The numerical simulation was also used to study the effect of the diameter/length ratio of the samples on the experimental results. The effect of the deformation in the bars’ ends, which contacted with the samples, was also studied in the numerical models.

Nonlinear FE simulations of structural behavior parameters of reinforced concrete beam with epoxy-bonded FRP

2015 ◽  
Vol 24 (1-2) ◽  
pp. 35-46 ◽  
Author(s):  
Saptarshi Sasmal ◽  
S. Kalidoss
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Adhesive Layer ◽  
Control Mode ◽  
Hydraulic Actuator ◽  
Element Analysis ◽  
Interfacial Stresses ◽  
Rc Structures ◽  
Laminate Thickness ◽  
Reinforcement Strain

AbstractIn the present study, investigations on fiber-reinforced plastic (FRP) plated-reinforced concrete (RC) beam are carried out. Numerical investigations are performed by using a nonlinear finite element analysis by incorporating cracking and crushing of concrete. The numerical models developed in the present study are validated with the results obtained from the experiment under monotonic load using the servo-hydraulic actuator in displacement control mode. Further, the validated numerical models are used to evaluate the influence of different parameters. It is found from the investigations that increase in the elastic modulus of adhesive layer and CFRP laminate increases the interfacial stresses whereas increase in laminate modulus decreases the displacement and reinforcement strain of the beam. It is also observed that increase in the adhesive layer can largely reduce the interfacial stresses, whereas increase in laminate thickness increases it. However, increase in laminate thickness decreases the displacement and reinforcement strain of the beam significantly. It is mention worthy that increase in laminate length reduces the interfacial stresses, whereas CFRP width change does not affect the interfacial stresses. The study will be useful for the design and practicing engineers for arriving at the FRP-based strengthening schemes for RC structures judiciously.

Rehabilitation of RC Structures Exposed to Salinity and Moisture Using CFRP

2014 ◽  
Vol 567 ◽  
pp. 488-493
Author(s):  
H. Fazli ◽  
Teo Wee
Keyword(s):  
Concrete Structures ◽  
Weight Ratio ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Rc Structures ◽  
Advanced Composite Materials ◽  
Cfrp Composite ◽  
Marine Concrete ◽  
General Rehabilitation ◽  
Physical And Chemical

Marine concrete structures such as harbors, ports and bridges are exposed simultaneously to the action of physical and chemical deterioration processes. Deterioration of marine concrete structures and its rehabilitation are challenges of the world of today. Recently, the increasing usage of carbon fiber reinforced polymer (CFRP) composite appears to be a solution for rehabilitation and strengthening of the concrete structures because of its physical and mechanical properties, such as high strength-to-weight ratio, high corrosion /environmental degradation resistance, and easy to handle during construction. In general, rehabilitation of concrete structures is usually done by two types of materials, it is either using cementitious or advanced composite materials. The aim of this paper is to address the issues and challenges of concrete structures in marine environments and strengthening these structures. In the initial part of this paper, an overview of the problems associated with marine environment on concrete structure will be discussed.

scholarly journals Castellated Steel Beams-A Torsional Analysis

2020 ◽  
Vol 9 (5) ◽  
pp. 536-540
Keyword(s):  
Failure Modes ◽  
Weight Ratio ◽  
High Strength ◽  
Steel Beams ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Moment Capacity ◽  
Flexure Mechanism ◽  
Shear Buckling ◽  
Castellated Beam

Practice of castellated beams (CBs) or perforated beams for several structures speedily gaining petition. This is because of the increased depth in the segment, high strength to weight ratio, light in weight, easy to erect, economical, and stronger. The principal advantages of the castellated beam are an attractive provision, an increase in vertical bending stiffness, & ease of service provision. The CBs is prepared from its virgin sections i.e. I beam by cutting it in a zigzag or any suitable cutting pattern and again rejoined it by welding therefore depth of the resulting section increases. The load-carrying capacity of the parent I section is increased with the same quantity of material and weight, due to an increase in depth of beams. Web post-buckling and lateral-torsional buckling failure occur when these beams are subjected to loading, this is the effect of an increase in depth of the castellated beams. There are five basic failure modes associated with castellated steel beams that need to be taken care of 1) Development of flexure mechanism. 2) Lateral-torsional buckling 3) Vierendeel mechanism 4) rupture of the welded joint in a web post 5) shear buckling of a web post. Therefore, in this research paper, an effort has been made to estimate the torsional moment capacity castellated beam for hexagonal or honeycomb opening with 300, 450, 600 & sinusoidal opening with different fillet radii.

Modelling the temperature effects at the interface between GFRP bar and concrete

2019 ◽  
Author(s):  
Ana Veljkovic ◽  
Valter Carvelli ◽  
Sandor Solyom ◽  
György L. Balázs ◽  
Mohammadali Rezazadeh
Keyword(s):  
Elevated Temperatures ◽  
Weight Ratio ◽  
Thermal Response ◽  
High Strength ◽  
Reinforcing Bars ◽  
Rc Structures ◽  
High Temperature Mechanical Properties ◽  
Pull Out ◽  
Glass Fibre Reinforced Polymer ◽  
Gfrp Bar

<p>GFRP (Glass Fibre Reinforced Polymer) reinforcing bars find recently increasing application in RC (Reinforced Concrete) structures. In addition to the main advantages, such as non-corrosive nature and high strength-to-weight ratio, the main drawback is their endurance under high temperature. Mechanical properties of GFRP bars and their bond to concrete decrease significantly when exposed to elevated temperatures. Thus, thermal response represents one of the main safety concerns for GFRP RC structures. This study focuses on the numerical modelling of the thermo-mechanical behaviour of GFRP bar and concrete bond. The temperature dependent bond law was calibrated using the experimental pull-out tests, and subsequently it was implemented in the finite element simulations. The validation of the methodology is obtained by comparison of corresponding experimental and numerical results.</p>

scholarly journals FLEXURAL CAPACITY ASSESSMENT OF BRICK AGGREGATED PRE-CRACKED RC BEAM STRENGTHENED WITH CARBON FIBER POLYMER

2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Niaz Md Mamun ◽  
G. M. Sadiqul Islam ◽  
Md Jahangir Alam
Keyword(s):  
Carbon Fiber ◽  
Failure Modes ◽  
Fiber Reinforced Polymers ◽  
Capacity Assessment ◽  
Rc Beam ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Carbon Fiber Reinforced Polymers ◽  
Rc Structures ◽  
Fiber Sheet

Ageing and improvements to design code has led to many existing RC structures made of locally available brick aggregates are now found structurally deficient and are in need of rehabilitation. This research emphases on flexural capacity assessment and investigation of failure modes of Carbon Fiber Reinforced Polymers (CFRP) strengthened brick aggregated RC beams. Flexural performance of the RC beam specimens are evaluated using four point bending method. Six RC beams (initially cracked) with CFRP strengthening were tested by varying (i) type of CFRP, (ii) reinforcing area, (iii) anchorage type; and (iv) number of CFRP layers. Two beams were tested as control specimens. Unidirectional carbon fiber sheet (Tow Sheet) and individually hardened continuous fiber strands woven into sheet form (Strand Sheet) were used. Simple flexure failure was obtained for unstrengthened RC beams while end plate and interfacial debonding were observed for the initially cracked CFRP strengthened RC beams. Strengthening of pre-cracked beams using Strand Sheet gave better performance compared to Tow sheet. Overall flexural strength improvement of CFRP strengthened beams varied from 12% to 34% with respect to unstrengthened beams depending on strengthening methods.

scholarly journals The Effectiveness of the DIC as a Measurement System in SRG Shear Strengthened Reinforced Concrete Beams

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 265
Author(s):  
Marco Francesco Funari ◽  
Salatore Verre
Keyword(s):  
Reinforced Concrete ◽  
Measurement System ◽  
Shear Crack ◽  
Weight Ratio ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Image Correlation ◽  
Rc Beams ◽  
Rc Structures ◽  
Number Of Layers

Steel Reinforced Grout (SRG) materials are generating considerable interest as strengthening system of reinforced concrete (RC) structures. They are finding increasing use in several civil engineering applications mainly due to the advantages they offer over traditional material such as high strength to weight ratio, ease of application, durability and low price. This paper describes the results of an experimental investigation carried out on SRG shear strengthened RC beams and gives evidence of the Digital Image Correlation (DIC) effectiveness as a measurement system. The tests performed had two main objectives: (i) assess the effectiveness of continuous and discontinuous U-wrapped jackets comprising a different number of layers and strips; (ii) assess the shear crack distribution during the tests by means of the DIC measurements. The results confirmed that reinforcing RC beams with SRG jackets can increase the load-bearing capacity; when the beam was reinforced with a continuous two-layered SRG strip, an increase of 84% was observed (compared to the unreinforced beam). The Linear Variable Differential Transformers (LVDT) measurements validated the results obtained by means of the DIC.

Precipitation in Al-Li-Zr alloys

1992 ◽  
Vol 50 (1) ◽  
pp. 186-187
Author(s):  
D.M. Vanderwalker
Keyword(s):  
Fracture Toughness ◽  
Precipitation Hardening ◽  
Weight Ratio ◽  
High Strength ◽  
Transmission Electron ◽  
Water Quench ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys ◽  
Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

TUNGUM ALLOY

Alloy Digest ◽  
2012 ◽  
Vol 61 (5) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Weight Ratio ◽  
High Strength ◽  
Fatigue Properties ◽  
Excellent Corrosion Resistance

Abstract Tungum alloy combines an unusually high strength-to-weight ratio, with ductility, excellent corrosion resistance, and good fatigue properties. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming. Filing Code: Cu-806. Producer or source: Tungum Ltd.

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