تعيين پاسخ تير هاي بتن آرمه تقويت شده با صفحات كامپوزيتي FRP تحت برش ، خمش و نيروي محوري با استفاده از تئوري ميدان فشاري اصلاح شده

چكيده انگليسي :

AbstractIn recent years using FRP composites in strengthening of reinforced concrete structures has beenincreasingly in process Within these furthermore the studies related to these fields have greatlyincreased Nevertheless because of complexity of shear transfer mechanism in reinforced concretemembers few of these studies have been concentrated on shear strengthening of reinforced concretebeams In the current study we have paid attention to shear strengthening of reinforced concrete beamsusing FRP sheets by using modified compression field theory Reinforced concrete beam considered inthis research is subjected to shear moment and axial force and is strengthened with FRP composites In order to study the existing models in this field first truss analogy model and then modifiedcompression field theory which is used in this research are explained extensively In modifiedcompression field theory equilibrium equations compatibility equations and stress strain relationships governed on the behavior of a reinforced concrete membrane element are extended The real status ofstress and strain in the element is found out by solving these equations Due to the volume ofcalculations in solving equations in this theory a software under the name of Membrane Element hasbeen developed To insure the complete understanding of modified compression field theory and toverify the software the results of Membrane Element software have been compared with theexperimental and analytical results given by other researchers and it has been shown that in one hand the results of this software in compare with experimental results have good accuracy and agreement and in the other hand the results of this software are compatible with the analytical results given byother researchers Then equations of this theory for a reinforced concrete membrane elementstrengthened with FRP sheets have been developed Afterward by using layer model and breakingbeam down into concrete layers and longitudinal steel elements we used these equations to analyze areinforced concrete beam strengthened with FRP sheets which is subjected to shear moment and axialforce Because of the considerable volume of calculations in this layer model and in solving equationsof modified compression field theory in members strengthened with FRP sheets a software that iscalled Shear Analysis has been provided By using this software we can inspect the behavior of areinforced concrete beam strengthened with FRP sheets which is subjected to shear moment and axialforce from start of loading to failure By using this software all factors of stress and strain in all pointsof beam could be calculated therefore it is easy to control the problem of FRP debonding in ShearAnalysis This action is done by limiting FRP strain to that corresponding to FRP debonding To verifythe Shear Analysis software the results were compared with experimental results given by otherresearchers in two stages In first stage the history of loading from several trial beams was determinedand compared with experimental history of loading In second stage the shear capacities of 69 trialbeams were calculated and compared with experimental shear capacities given by other researches The results in both stages have shown good agreement and acceptable accuracy At the end aparametric study was conducted to investigate influensive effects on behavior of reinforced concretebeams strengthened with FRP sheets such as transverse steel ratio longitudinal steel ratio FRP ratioand the a d ratio of beam In this investigation a lot of information about behavior of reinforcedconcrete beams strengthened with FRP sheets was achieved including the definition of FRP optimumratio Furthermore by investigating the effect of longitudinal steel ratio and the a d ratio of beam onoptimum ratio of FRP it was figured out that with increase of longitudinal steel ratio the optimumratio of FRP will increase and with increase of the a d ratio of beam the optimum amount of FRPw

نورمحمدي، محسن

تعيين پاسخ تير هاي بتن آرمه تقويت شده با صفحات كامپوزيتي FRP تحت برش ، خمش و نيروي محوري با استفاده از تئوري ميدان فشاري اصلاح شده

مود هاي گسيختگي , تشابه خرپايي , آرماتو رهاي طولي وعرضي , فولاد فشاري ، كششي