• Title/Summary/Keyword: Effective Failure Effect

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Strength model for square concrete columns confined by external CFRP sheets

  • Benzaid, Riad;Mesbah, Habib Abdelhak
    • Structural Engineering and Mechanics
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    • v.46 no.1
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    • pp.111-135
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    • 2013
  • An experimental study has been carried out on square plain concrete (PC) and reinforced concrete (RC) columns strengthened with carbon fiber-reinforced polymer (CFRP) sheets. A total of 78 specimens were loaded to failure in axial compression and investigated in both axial and transverse directions. Slenderness of the columns, number of wrap layers and concrete strength were the test parameters. Compressive stress, axial and hoop strains were recorded to evaluate the stress-strain relationship, ultimate strength and ductility of the specimens. Results clearly demonstrate that composite wrapping can enhance the structural performance of square columns in terms of both maximum strength and ductility. On the basis of the effective lateral confining pressure of composite jacket and the effective FRP strain coefficient, new peak stress equations were proposed to predict the axial strength and corresponding strain of FRP-confined square concrete columns. This model incorporates the effect of the effective circumferential FRP failure strain and the effect of the effective lateral confining pressure. The results show that the predictions of the model agree well with the test data.

Effects of Youngkaechulgamtang on the Kidney Function (영계출감탕의 신기능에 미치는 영향)

  • Kim, Tae-Hee;Yang, Ki-Sook;Park, Seung-Ah
    • Korean Journal of Pharmacognosy
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    • v.31 no.3
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    • pp.364-372
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    • 2000
  • The Youngkaechulgamtang(Y) is composed of four herbal drugs, including Hoelen(H), Cinnamomi Ramulus(C), Atractylodis Rhizoma Alba(A) and Glycyrrhizae Radix(G). In oriental medicine literatures, Youngkaechulgamtang is described to be effective in headache, inflammation, uremia, gastritis, diarrhea, hypertension. To estimate the clinical effectiveness of Youngkaechulgamtang, several pharmacological experiments were carried out. The results are summarized as follows: On $HgCl_2-induced$ renal failure rat, Youngkaechulgamtang showed the significant increase of $Na^+,\;K^+,\;Cl^-$ contents in urine and the significant decrease of creatinine and BUN concentrations in serum. Youngkaechulgamtang was more effective than mixture of 4 ingredients in the urine volume and excretion of electrolytes. In the diuretic effect, Hoelen and Atractylodis Rhizoma Alba were more effective than other drugs.

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A Proposal of Minimum Steel Ratio Considering Size Effect for Flexural Reinforced Concrete Member (크기효과가 고려된 철근콘크리트 휨 부재의 최소철근비 제안)

  • Yoo, Sung-Won;Her, Yoon
    • Journal of the Korean Society of Safety
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    • v.25 no.6
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    • pp.128-136
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    • 2010
  • In according with concrete structural design standard, it is common designing flexure reinforcement concrete to induce tension failure. So reinforcing ratio is limited to inducing tension failure. And maximum reinforcing ratio is regulated to protecting concrete compression strength caused by over reinforced building. Minimum reinforcing ratio is also limited in designing standard to protecting brittle failure as extremely using less reinforcing bar. But in minimum reinforcing ratio it is extremely conservative or it is sometimes impossible to induce stable tension-failure because they are depending on yield failure and experienced method and concrete designing standard strength. Therefore the purpose of the present paper is to evaluate the flexural behavior of minimum steel ratio of reinforced concrete of beams and to propose the guide-line of equation of minimum steel ratio by performing static flexural test of 16 beams according to size effect, number of steel, yielding stress of steel, and concrete compressive strength which are presumed effective variables. From experimental results, the equation of minimum steel ratio was newly proposed considered size effect.

The Shear Resistance of Rc Deep Beam with Web Opening Repaired and Reinforced by Fiber Sheets After Shear Failure (깊이가 큰 철근콘크리트 유공보의 보수·보강 전후의 내력에 관한 연구)

  • Yang, Chang-Jin
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.3
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    • pp.149-158
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    • 2004
  • In this study, deep beam specimens are designed to have the effective shear span to depth ratio 1.0 and web opening within effective shear region. The purpose of this study is to investigate experimentally the shear strengthening effect between before failure and after failure upon using fiber sheets for RC deep beam with opening in web. The results can be summarized as follows; 1)When deep beams with web opening were failed in shear, their initial diagonal crack load and crack width were not influenced by their types of the arranged steel bars. 2)Deep beam with the horizontal reinforced bar was effective in the ultimate load of deep beam with web opening in shear failure 3)There were the approximate values between the experimental values and the analysis of finite element method. 4)The ultimate failure strengths of the repaired and strengthened specimens were increased about 34.4%~83.8% in comparison with specimens not to be strengthened.

Differential Effects of Recovery Efforts on Products Attitudes (제품태도에 대한 회복노력의 차별적 효과)

  • Kim, Cheon-GIl;Choi, Jung-Mi
    • Journal of Global Scholars of Marketing Science
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    • v.18 no.1
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    • pp.33-58
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    • 2008
  • Previous research has presupposed that the evaluation of consumer who received any recovery after experiencing product failure should be better than the evaluation of consumer who did not receive any recovery. The major purposes of this article are to examine impacts of product defect failures rather than service failures, and to explore effects of recovery on postrecovery product attitudes. First, this article deals with the occurrence of severe and unsevere failure and corresponding service recovery toward tangible products rather than intangible services. Contrary to intangible services, purchase and usage are separable for tangible products. This difference makes it clear that executing an recovery strategy toward tangible products is not plausible right after consumers find out product failures. The consumers may think about backgrounds and causes for the unpleasant events during the time gap between product failure and recovery. The deliberation may dilutes positive effects of recovery efforts. The recovery strategies which are provided to consumers experiencing product failures can be classified into three types. A recovery strategy can be implemented to provide consumers with a new product replacing the old defective product, a complimentary product for free, a discount at the time of the failure incident, or a coupon that can be used on the next visit. This strategy is defined as "a rewarding effort." Meanwhile a product failure may arise in exchange for its benefit. Then the product provider can suggest a detail explanation that the defect is hard to escape since it relates highly to the specific advantage to the product. The strategy may be called as "a strengthening effort." Another possible strategy is to recover negative attitude toward own brand by giving prominence to the disadvantages of a competing brand rather than the advantages of its own brand. The strategy is reflected as "a weakening effort." This paper emphasizes that, in order to confirm its effectiveness, a recovery strategy should be compared to being nothing done in response to the product failure. So the three types of recovery efforts is discussed in comparison to the situation involving no recovery effort. The strengthening strategy is to claim high relatedness of the product failure with another advantage, and expects the two-sidedness to ease consumers' complaints. The weakening strategy is to emphasize non-aversiveness of product failure, even if consumers choose another competitive brand. The two strategies can be effective in restoring to the original state, by providing plausible motives to accept the condition of product failure or by informing consumers of non-responsibility in the failure case. However the two may be less effective strategies than the rewarding strategy, since it tries to take care of the rehabilitation needs of consumers. Especially, the relative effect between the strengthening effort and the weakening effort may differ in terms of the severity of the product failure. A consumer who realizes a highly severe failure is likely to attach importance to the property which caused the failure. This implies that the strengthening effort would be less effective under the condition of high product severity. Meanwhile, the failing property is not diagnostic information in the condition of low failure severity. Consumers would not pay attention to non-diagnostic information, and with which they are not likely to change their attitudes. This implies that the strengthening effort would be more effective under the condition of low product severity. A 2 (product failure severity: high or low) X 4 (recovery strategies: rewarding, strengthening, weakening, or doing nothing) between-subjects design was employed. The particular levels of product failure severity and the types of recovery strategies were determined after a series of expert interviews. The dependent variable was product attitude after the recovery effort was provided. Subjects were 284 consumers who had an experience of cosmetics. Subjects were first given a product failure scenario and were asked to rate the comprehensibility of the failure scenario, the probability of raising complaints against the failure, and the subjective severity of the failure. After a recovery scenario was presented, its comprehensibility and overall evaluation were measured. The subjects assigned to the condition of no recovery effort were exposed to a short news article on the cosmetic industry. Next, subjects answered filler questions: 42 items of the need for cognitive closure and 16 items of need-to-evaluate. In the succeeding page a subject's product attitude was measured on an five-item, six-point scale, and a subject's repurchase intention on an three-item, six-point scale. After demographic variables of age and sex were asked, ten items of the subject's objective knowledge was checked. The results showed that the subjects formed more favorable evaluations after receiving rewarding efforts than after receiving either strengthening or weakening efforts. This is consistent with Hoffman, Kelley, and Rotalsky (1995) in that a tangible service recovery could be more effective that intangible efforts. Strengthening and weakening efforts also were effective compared to no recovery effort. So we found that generally any recovery increased products attitudes. The results hint us that a recovery strategy such as strengthening or weakening efforts, although it does not contain a specific reward, may have an effect on consumers experiencing severe unsatisfaction and strong complaint. Meanwhile, strengthening and weakening efforts were not expected to increase product attitudes under the condition of low severity of product failure. We can conclude that only a physical recovery effort may be recognized favorably as a firm's willingness to recover its fault by consumers experiencing low involvements. Results of the present experiment are explained in terms of the attribution theory. This article has a limitation that it utilized fictitious scenarios. Future research deserves to test a realistic effect of recovery for actual consumers. Recovery involves a direct, firsthand experience of ex-users. Recovery does not apply to non-users. The experience of receiving recovery efforts can be relatively more salient and accessible for the ex-users than for non-users. A recovery effort might be more likely to improve product attitude for the ex-users than for non-users. Also the present experiment did not include consumers who did not have an experience of the products and who did not perceive the occurrence of product failure. For the non-users and the ignorant consumers, the recovery efforts might lead to decreased product attitude and purchase intention. This is because the recovery trials may give an opportunity for them to notice the product failure.

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A Study on the Factors Affecting the Service Failure ZOT and severity Perception (서비스실패의 허용영역과 심각성 지각에 영향을 미치는 요인에 관한 연구)

  • Ock, Jung Won;Yun, Dae Hoong;Eum, Seong Won;Yim, Sun Joo
    • Journal of Service Research and Studies
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    • v.6 no.2
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    • pp.215-232
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    • 2016
  • As the development of service marketing, research on service failure has gained more and more attention. This research aims to explore factors influencing the service failure severity perception, focus on consumers' internal propensity, ZOT(zone of tolerance) about service and comparison with other consumers in service failure situation. According to study results, it revealed that past experience satisfaction has negative effect on the zone of tolerance about service failure. Company image also has negative effect on the ZOT about service failure. While service importance has negative effect on the ZOT about service failure, it has positive effect on the perceive service failure severity. The ZOT about service failure has negative effect on perceived serviced failure severity. In contrast, social comparison perception level has no effect on perceived service failure severity, and negative affectivity also has no effect on that. In Conclusion, five hypothesis are accepted among seven hypothesis. This study gives important point to researchers and service providers in the service industry. For researchers, the result will be helpful them to further develop service failure and recovery framework. For service providers, the results will suggest specific guidelines for recovering the service failure. They can place emphasis on the serious point, so they can get a effective performance from the recovery strategy.

Strength and strain enhancements of concrete columns confined with FRP sheets

  • Campione, G.;Miraglia, N.;Papia, M.
    • Structural Engineering and Mechanics
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    • v.18 no.6
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    • pp.769-790
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    • 2004
  • The compressive behavior up to failure of short concrete members reinforced with fiber reinforced plastic (FRP) is investigated. Rectangular cross-sections are analysed by means of a simplified elastic model, able also to explain stress-concentration. The model allows one to evaluate the equivalent uniform confining pressure in ultimate conditions referred to the effective confined cross-section and to the effective stresses in FRP along the sides of section; consequently, it makes it possible to determine ultimate strain and the related bearing capacity of the confined member corresponding to FRP failure. The effect of local reinforcements constitute by single strips applied at corners before the continuous wrapping and the effect of round corners are also considered. Analytical results are compared to experimental values available in the literature.

Behavior of Failure of Agricultural Reservoirs Embankment Reinforced by Geotextile under Overtopping Condition (지오텍스타일로 보강된 농업용 저수지 제체의 붕괴거동)

  • Lee, Dal Won;Noh, Jae Jin
    • Journal of The Korean Society of Agricultural Engineers
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    • v.56 no.2
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    • pp.59-64
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    • 2014
  • In this study, the large scale test was performed to investigate the behavior of failure for the embankment and spillway transitional zone by overtopping. The pore water pressure, earth pressure, settlement and failure pattern of covering embankment with geotextile were compared and analyzed. The pore water pressure showed a small change in the spillway transition zone and core, indicating that the geotextile efficiently reinforced the embankment. The earth pressure decreased the infiltration of the pore water only in inclined cores type to secure local stability. The behavior of failure started from the bottom and gradually progressed upwards. After the intermediate overtopping period (100 min), width and depth of the seepage erosion were very small due to the effect of geotextile which delayed failure. Therefore, the reinforced method by geotxtile was a very effective method to respond to the emergency due to overtopping.

Reliability studies on RC beams exposed to fire based on IS456:2000 design methods

  • Balaji, Aneesha;Aathira, M.S.;Pillai, T.M. Madhavan;Nagarajan, Praveen
    • Structural Engineering and Mechanics
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    • v.59 no.5
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    • pp.853-866
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    • 2016
  • This paper examines a methodology for computing the probability of structural failure of reinforced concrete beams subjected to fire. The significant load variables considered are dead load, sustained live load and fire temperature. Resistance is expressed in terms of moment capacity with random variables taken as yield strength of steel, concrete class (or grade of concrete), beam width and depth. The flexural capacity is determined based on the design equations recommended in Indian standard IS456:2000. Simplified method named $500^{\circ}C$ isotherm method detailed in Eurocode 2 is incorporated for fire design. A transient thermal analysis is conducted using finite element software ANSYS$^{(R)}$ Release15. Reliability is evaluated from the initial state to 4h of fire exposure based on the first order reliability method (FORM). A procedure is coded in MATLAB for finding the reliability index. This procedure is validated with available literature. The effect of various parameters like effective cover, yield strength of steel, grade of concrete, distribution of reinforcement bars and aggregate type on reliability indices are studied. Parameters like effective cover of concrete, yield strength of steel has a significant effect on reliability of beams. Different failure modes like limit state of flexure and limit state of shear are checked.

Validity Evaluation of Determination Methods of Effective Concrete Strut Strength (콘크리트 스트럿 유효강도 결정방법의 적합성 평가)

  • 윤영묵
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.595-599
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    • 2003
  • For implementation of the strut-tie model approach to the practical analysis and design of structural concrete, the effective strengths of concrete struts in a strut-tie model, which have a crucial effect on the determination of strut and tie forces and the validity verification of strut-tie model's geometric compatibility condition, have to be determined accurately. In this study, the validity of the methods for determining the effective strengths of concrete struts was evaluated by conducting the strut-tie model analyses of the three reinforced concrete deep beams tested to failure with the effective strengths of concrete struts obtained from the suggested determination methods.

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