Analysis and modelling of the seismic behaviour of high ... - Ingegneria

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5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES Figure 5.46. Modified joint depth after the numerical analyses The differences between the analytical model, i.e. the equations previously illustrated necessary to determine the single joint mechanism resistance, and the experimental values obtained from the tests in terms of maximum average shear force resisted at the joint region are introduced in the following Table 5.18. ANALYTICAL PROCEDURE Inner Resistance Outer Resistance Mechanism Vj,rd [kN] Mj,Rd [kNm] PANEL ZONE CONCRETE COMPRESSION STRUT HORIZONTAL BEARING 583 134 230 47 Mj,Rd [kNm] Vj,rd [kN] Mechanism 66 152 CONCRETE COMPRESSION FIELD 1231 437 77 194 BOND Mj,Rd,MINIMUM Mj,Rd,MINIMUM 277 66 Σ Mj,Rd,MINIMUM [kNm] 344 Vj,rd [kN] Analytical Value 871 Experimental Value 915 Difference –4,8% Table 5.18. Comparison between numerical and experimental results after the numerical analyses ds 0.9ds 239
5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES The analytical values obtained from the previous equations well agree with the true joint shear resistances obtained from the experimental tests in the case that, an increase in the shear resistance of the steel web panel (when subjected to high cyclic strains) is allowed. Hence, in equation 5.18, the factor 1/√3 is substituted by a value equal to unity: 240 f ym, d , cw Vj , wps = 0,7 ⋅ ⋅min( Av ; tcw ⋅ ds ) + ∆ Vj , swp ( 5.74 ) 1 Note that, in this phase, the single mechanism resistance evaluated by means of the analytical model, does not take into account the partial safety factor value equal to 1,3 as prescribed by the Capacity Design Principle. Furthermore, the resistance values are determined considering the real material strengths obtained from specific tests conducted on concrete and steel samples. In fact, it is intended to make a direct comparison to establish the precision of the proposed analytical equations. Of course, at the design stage, it is necessary to account for all the relevant safety factors as already foreseen in the equations previously presented. By means of these modifications it was possible to calibrate the proposed analytical formulas: a substantial increase in the accuracy of the predicted joint shear resistance compared with that obtained from the experimental results. The difference between the analytical and experimental results has been modified from a 20% to a 5% of error, as reported in the Table. 5.8 Conclusions This part of the Ph.D. thesis has been written with the intent of underlining the importance of the studies conducted on Innovative Beam-to-Column Composite Joints in order to provide the reinforced concrete structures of the necessary amount of ductility in those critical zones usually strongly affected by the occurrence of seismic events. The general recommendation is to reinforce some strategic points of the building, as the joints of the 1 st storey, allowing in this manner to save the structure from a global collapse due to localised brittle type of failures. Both the solutions studied, with long and short steel profile encased in the concrete column, as expected, revealed to be effective in order to greatly improve the performance of the concrete members in terms of strength and ductility at large deformations. In fact, it can be stated that also the short steel profile stump is able to guarantee an adequate amount of resistance and ductility at the joint critical
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Dipartimento di Ingegneria Meccanic
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UNIVERSITÀ DEGLI STUDI DI TRENTO D
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Ai miei genitori
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INDEX 1 INTRODUCTION...............
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INDEX iii 4.10.3 Results of the PsD
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1.1 Introduction 1 1 INTRODUCTION I
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1. INTRODUCTION imposes precise con
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1. INTRODUCTION joints whilst 2D mo
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7 2 DUCTILITY AND SEISMIC RESPONSE
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2. DUCTILITY AND SEISMIC RESPONSE O
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5. SEISMIC BEHAVIOUR OF RC COLUMNS
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Analysis and modelling of the seismic behaviour of high ... - Ingegneria

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