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چكيده انگليسي :

162 Numerical Modeling of Fiber Reinforced Concrete Considering a Probabilistic Distribution For Fibers Omid Daeijavad o daeijavad@cv iut ac ir Date of Submission July 03 2011 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors Dr Amir Mahdi Halabian mahdi@cc iut ac ir AbstractNow days there is an increasing trends for the use of fiber reinforced concrete FRC to construct thestructures more strongly Cementitious matrices show in general similar mechanical characteristics thatdistinguish them from metallic and polymeric matrices i e relatively high compressive strength poor tensilestrength and brittleness at failure Adding steel fibers in Portland cement concrete leads to enhance its tensileproperties delay cracking and increase its toughness Because the post cracking strength of this materials isnot negligible the crack bridging capacity provide by fibers may replace partial or completely conventionalsteel reinforcement The cracking bridging capacity provided by steel fibers improves both the toughness anddurability of concrete several parameters such as geometrical and mechanical features of fibers and concrete affect thebehavior of FRC therefore studing behaviors is necessary In previous research analysis of FRCs have beendone by experimental investigations and also section analysis have been done by experimental and numericalinvestigations In numerical investigations the modeling have been proceed with continuum element According to past researches the effectiveness of distribution and orientation in concrete matrix play themain roles in FRC behavior The objective of present thesis was to develop a new model for simulating fibers in real conditions andat the end of the thesis the FRC behavior have been studied under static loads For modeling the nonflexiblefibers have been chosen and the proposed distributions in previous studies applied to the models and finally agoverned distribution was proposed In present thesis a distribution algorithm is written in a numerical solversoftware ABAQUS which uses finite element method FEM This algorithm defined by a python code Forconcrete element damage concrete plasticity model is chosen and for steel element elasto plastic behavior isconsidered The influence of correlation between fiber and concrete is one of the most important facts on FRCbehavior So this fact is investigated related to whole previous suggested models and it has been shown thatcohesive behavior contact is the most appropriate model for expressing continuity between fiber andconcrete Because application of mentioned model is very time consuming and needs high cupable hardwareso another numerical method which is called embedded model is used In sequence a non linear solutionmethod is used to analysis the FRC models Finally two cylindrical and cubic specimens are chosen fornumerical tests The diameter and height of cylindrical specimen were 150 mm and 300 mm respectively with 0 5 percent fiber volume fraction and also the cubic specimen has the length of 400 mm height of 100mm and width of 100 mm containing 1 percent fiber volume fraction These two models have beeninvestigated under static loads and their behaviors under bending and tensile were studied Numericalpredictions are compared to observations from experiments to demonstrate the ability to predict such FRCmeaningfully There is a good agreement between numerical and experimental results By using the proposednumerical model in this thesis the behavior of FRC could be investigated under various static and dynamicloads KeywordsFiber Reinforced Concrete Behavior Simulation Modeling Finite Element Method Pullout Cohesive Behavior Contact Non linear Static Analysis ABAQUS

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شبيه سازي , مدل رفتاري , مدل سازي , مدل آسيب , بيرون كشيدگي , تماس چسباننده , حل به روش اجزا محدود , تحليل استاتيكي غير خطي , آباكوس