Flexural fatigue life analysis of unsaturated polyester-methyl methacrylate polymer concrete

Yeon, Kyu-Seok,Choi, Yoon-Sang,Kim, Kwan-Kyu,Yeon, Jung Heum Elsevier 2017 Construction and Building Materials Vol.140 No.-

<P><B>Abstract</B></P> <P>Laboratory and statistical evaluations were performed to examine the flexural fatigue performance of unsaturated polyester-methyl methacrylate (UP-MMA) polymer concrete. Target stress levels were 0.9, 0.8, 0.7, and 0.6 with a fixed stress ratio of 0.1. A 5Hz sinusoidal load with a constant-amplitude frequency was applied to a prismatic specimen (100×100×400mm) using a 250-kN universal testing machine (UTM). MMA contents considered were 0, 10, 20, and 30wt.%. In addition, the two-parameter Weibull distribution was employed to analyze the fatigue life probability distributions of UP-MMA polymer concrete. Three different analysis methods—the graphical method, method of moment, and method of maximum likelihood estimation—were applied to estimate the distribution parameters of the two-parameter Weibull distribution. The results have shown that the two-parameter Weibull distribution describes the fatigue life probability distributions of UP-MMA polymer concrete with quite high statistical correlation coefficients. Also, the goodness-of-the-fit of the fatigue life data obtained was verified by means of the Kolmogorov-Smirnov test, which were all accepted at a 5% significance level. Finally, a single-log fatigue equation was derived to predict the fatigue life of UP-MMA polymer concrete.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Laboratory evaluations were performed to examine the flexural fatigue behavior of UP-MMA polymer concrete. </LI> <LI> A two-parameter Weibull distribution was used to analyze the fatigue life probability distributions. </LI> <LI> The goodness-of-the-fit of the fatigue life data was verified by means of the Kolmogorov-Smirnov test. </LI> <LI> A single-log fatigue equation was derived to predict the fatigue life of UP-MMA polymer concrete. </LI> </UL> </P>

Experimental Investigation on Fatigue Strength of Joints between SRC Beams and Concrete-Filled RHS Columns

Qingjun Xian,Le-Wei Tong,Liying Zhou,Yiyi Chen 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.5

Fatigue behavior, failure mechanism and fatigue strength of joints between steel reinforced concrete (SRC) beams and Concrete Filled Rectangular Hollow Section (CFRHS) columns is discussed in this paper. Three identical beam-to-column joint specimens were designed and tested under static loading and two stages of fatigue loading. In the first stage of fatigue loading, the specimens were subjected to design fatigue load for 2 million cycles, while during the second stage, they were loaded to failure under increased fatigue load in order to know failure mechanism and fatigue strength. It is found that the joints satisfied design requirements when subjected to static loading and design fatigue loading. Fatigue failure occurred after these joints were applied higher-level fatigue loading. The crack initiated at the weld toe of stud or stirrup hole in the upper flange of I-shaped steel in certain SRC beam, and then it propagated along flange width in winding trajectory until fatigue fracture occurred. Stress amplitude of tension flange in SRC beam can be regarded as the parameter representing fatigue strength of the joints. S-N curves in related codes are selected to evaluate fatigue strength of the joints. The design method is suggested to consider fatigue design of the joints.

Experimental Study and Analytical Modeling on Fatigue Properties of Pervious Concrete Made with Natural and Recycled Aggregates

Xudong Chen,Dandan Shi,Nan Shen,Shengtao Li,Saisai Liu 한국콘크리트학회 2019 International Journal of Concrete Structures and M Vol.13 No.1

As a solid pollutant, the recycled aggregate can be reused to replace the natural aggregate to cast pervious concrete, promoting resource recycling and reducing environmental pollution. Pervious concrete is usually applied to transportation engineering as pavements and decks, which are often subjected to fatigue loads in service. Therefore, it is essential to investigate the fatigue mechanical properties of pervious concrete. In this study, four-point cyclic bending loading test of natural aggregate pervious concrete and recycled aggregate pervious concrete were conducted under four different stress levels. By analyzing the experimental results, the mechanical performances, including hysteresis curve characteristics, damping ratio, dynamic elastic modulus and cyclic strain, of two kinds of pervious concrete under cyclic loading were revealed. Based on the improved EPF model, the relationship between fracture parameters, plastic strain and unloading strain were obtained. Besides, the relationship between the loading cycles and the ratio of plastic strain to unloading strain was received according to fatigue testing data under different stress levels. Further, the simplified fatigue model of pervious concrete was proposed and the experimental data was fitted with the model results. The fitting result reached a good agreement.

Flexural behaviour of GFRP reinforced concrete beams under cyclic loading

A. Ramachandra Murthy,P. Gandhi,D.M. Pukazhendhi,F. Giftson Samuel,S. Vishnuvardhan 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.3

This paper examines the flexural performance of concrete beams reinforced with glass fibre-reinforced polymer (GFRP) bars under fatigue loading. Experiments were carried out on concrete beams of size 1500×200×100 mm reinforced with 10 mm and 13 mm diameter GFRP bars under fatigue loading. Experimental investigations revealed that fatigue loading affects both strength and serviceability properties of GFRP reinforced concrete. Experimental results indicated that (i) the concrete beams experienced increase in deflection with increase in number of cycles and failed suddenly due to snapping of rebars and (ii) the fatigue life of concrete beams drastically decreased with increase in stress level. Analytical model presented a procedure for predicting the deflection of concrete beams reinforced with GFRP bars under cyclic loading. Deflection of concrete beams was computed by considering the aspects such as stiffness degradation, force equilibrium equations and effective moment of inertia. Nonlinear finite element (FE) analysis was performed on concrete beams reinforced with GFRP bars. Appropriate constitutive relationships for concrete and GFRP bars were considered in the numerical modelling. Concrete non linearity has been accounted through concrete damage plasticity model available in ABAQUS. Deflection versus number of cycles obtained experimentally for various beams was compared with the analytical and numerical predictions. It was observed that the predicted values are comparable (less than 20% difference) with the corresponding experimental observations.

Modeling of Chloride Ion Diffusion in Concrete under Fatigue Loading

Tao Yang,Bowen Guan,Guoqiang Liu,Yanshun Jia 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.1

It is common for reinforced concrete in the saline region to bear fatigue loading and chloride induced corrosion, which has become one of the main causes of structural failure of reinforced concrete. The objective of this paper is to investigate the characteristics of chloride ion transport in concrete under fatigue loading. A new theoretical model describing the chloride ion transport in saturated concrete under fatigue loading is proposed. In this model, the concrete is divided into two parts, matrix and microcrack, to characterize the chloride diffusion coefficient of concrete based on crack area. The influence of fatigue damage on the microcrack area of concrete is quantitatively analyzed and the relationship between fatigue loading and chloride diffusion coefficient is established. Then, based on Fick’s second law, the model is proposed and solved by analytical solution. Some experiments are conducted to verify the proposed model and the simulated and measured results are in good agreement with each other. Finally, the characteristics of chloride ion transport under different influencing factors are analyzed using the proposed model.

Experimental Study on Damage Evolution Behavior of Self-Compacting Rubberized Concrete under Direct Tensile Fatigue Loading

Xudong Chen,Chen Chen 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.11

Fatigue properties of self-compacting rubberized concrete (SCRC) under axial tension are rare.To explore the fatigue damage evolution of SCRC, the direct tensile fatigue test and residual mechanical test were conducted. According to the experimental results, the linear relationship between the fatigue life and secondary strain rate also exists in tensile fatigue test of SCRC, and the slope value is similar to the compressive and direct tensile fatigue test of ordinary concrete. Further, the downtrend of the residual secant modulus is more obvious than the residual strength. In addition, the direct tensile fatigue damage evolution of SCRC under different stress levels can be predicted by the Isojeh’s model.

누적손상을 고려한 강섬유보강 콘크리트의 피로파괴 특성

김동호 ( Kim Dong Ho ),홍창우 ( Hong Chang Woo ),이주형 ( Lee Ju Hyong ),이봉학 ( Lee Bong Hak ) 한국농공학회 2002 韓國農工學會誌 : 전원과 자원 Vol.44 No.2

Concrete containing discontinuous discrete steel fiber in a normal concrete is called steel fiber reinforced concrete(SFRC). Tensile as well as flexural strengths of concrete could be substantially increased by introducing closely spaced fibers which delay the onset of tension cracks and increase the tension strength of cracks. However, many properties of SFRC have not been investigated, especially properties on repeated loadings. Thus, the purposes of this dissertation is to study the flexural fatigue characteristics of SFRC considering cumulative damage. A series of experimental tests such as compressive strength, splitting tensile strength, flexural strength, flexural fatigue, and two steps stress level fatigue were conducted to clarify the basic properties and fatigue-related properties of SFRC. The main experimental variables were steel fiber fraction (0, 0.4, 0.7, 1, 1.5%), aspect ratio (60, 83). The principal results obtained through this study are as follows: The results of flexural fatigue tests showed that the flexural fatigue life of SFRC is approxmately 65% of ultimate strength, while that of plain is less than 58%. Especially, the behavior of flexural fatigue life shows excellent performance at 1.0% of steel-fiber volume fraction. The cumulative damage test of high-low two stress levels is within the value of 0.6 ∼ 1.1, while that of low-high stress steps is within the value of 2.4 ∼ 4.0.

Crack propagation in flexural fatigue of concrete using rheological-dynamical theory

Aleksandar Pančić,Dragan D. Milašinović,Danica Goleš 사단법인 한국계산역학회 2021 Computers and Concrete, An International Journal Vol.27 No.1

The concrete fatigue analysis can be performed with the use of fracture mechanics. The fracture mechanics defines the fatigue crack propagation as the relationship of crack growth rate and stress intensity factor. In contrast to metal, the application of fracture mechanics to concrete is more complicated and therefore many authors have introduced empirical expressions using Paris law. The topic of this paper is development of a new prediction of fatigue crack propagation for concrete using rheological-dynamical analogy (RDA) and finite element method (FEM) in the frame of linear elastic fracture mechanics (LEFM). The static and cyclic fatigue three-point bending tests on notched beams are considered. Verification of the proposed approach was performed on the test results taken from the literature. The comparison between the theoretical model and experimental results indicates that the model proposed in this paper is valid to predict the crack propagation in flexural fatigue of concrete.

Influence of high-cycle fatigue on the tension stiffening behavior of flexural reinforced lightweight aggregate concrete beams

How-Ji Chen,Te-Hung Liu,Chao-Wei Tang,Wen-Po Tsai 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.6

The objective of this study was to experimentally investigate the bond-related tension stiffening behavior of flexural reinforced concrete (RC) beams made with lightweight aggregate concrete (LWAC) under various high-cycle fatigue loading conditions. Based on strain measurements of tensile steel in the RC beams, fatigue-induced degradation of tension stiffening effects was evaluated and was, compared to reinforced normal weight concrete (NWC) beams with equal concrete compressive strengths (40 MPa). According to applied load-mean steel strain relationships, the mean steel strain that developed under loading cycles was divided into elastic and plastic strain components. The experimental results showed that, in the high-cycle fatigue regime, the tension stiffening behavior of LWAC beams was different from that of NWC beams; LWAC beams had a lesser reduction in tension stiffening due to a better bond between steel and concrete. This was reflected in the stability of the elastic mean steel strains and in the higher degree of local plasticity that developed at the primary flexural cracks.

Influence of high-cycle fatigue on the tension stiffening behavior of flexural reinforced lightweight aggregate concrete beams

Chen, How-Ji,Liu, Te-Hung,Tang, Chao-Wei,Tsai, Wen-Po Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.6

The objective of this study was to experimentally investigate the bond-related tension stiffening behavior of flexural reinforced concrete (RC) beams made with lightweight aggregate concrete (LWAC) under various high-cycle fatigue loading conditions. Based on strain measurements of tensile steel in the RC beams, fatigue-induced degradation of tension stiffening effects was evaluated and was, compared to reinforced normal weight concrete (NWC) beams with equal concrete compressive strengths (40 MPa). According to applied load-mean steel strain relationships, the mean steel strain that developed under loading cycles was divided into elastic and plastic strain components. The experimental results showed that, in the high-cycle fatigue regime, the tension stiffening behavior of LWAC beams was different from that of NWC beams; LWAC beams had a lesser reduction in tension stiffening due to a better bond between steel and concrete. This was reflected in the stability of the elastic mean steel strains and in the higher degree of local plasticity that developed at the primary flexural cracks.