Analysis and modelling of the seismic behaviour of high ... - Ingegneria
Analysis and modelling of the seismic behaviour of high ... - Ingegneria
Analysis and modelling of the seismic behaviour of high ... - Ingegneria
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5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES<br />
thus increases <strong>the</strong> shear joint strength. In accordance with <strong>the</strong>se assumptions, for<br />
<strong>the</strong> two <strong>seismic</strong> load combination (design case 2 <strong>and</strong> design case 3), we must<br />
check that:<br />
1. Vj,Rd > Vj,Sd = 0,8 [(Mbeam,Rd,right + Mbeam,Rd,left) / ds – Vc] ( 5.52 )<br />
where Vc is <strong>the</strong> average shear force at collapse in <strong>the</strong> web panel equal to:<br />
208<br />
(Vcolumn,top + Vcolumn,bottom) / 2 = (Mcolumn,Rd,top + Mcolumn,Rd,bottom) / (Hc – ds) ( 5.53 )<br />
assuming that <strong>the</strong> zero-moment points are located in <strong>the</strong> middle section <strong>of</strong> <strong>the</strong><br />
columns <strong>the</strong> equilibrium condition M beam = M column is satisfied.<br />
2. Mj,Rd > 1,3 (Mbeam,Rd,right + Mbeam,Rd,left) ( 5.54 )<br />
In view <strong>of</strong> <strong>the</strong> resistance evaluation, <strong>the</strong> following equations obtained from<br />
equilibrium <strong>of</strong> forces in <strong>the</strong> joint panel zone are used:<br />
Mj,Rd = Vjoint,inner · dinner + Vjoint,outer · douter ( 5.55 )<br />
Vj,Rd = Mj,Rd / ds ( 5.56 )<br />
5.5 The experimental test programme<br />
5.5.1 Design <strong>of</strong> <strong>the</strong> reduced section <strong>of</strong> <strong>the</strong> specimen to be tested<br />
For what concerns <strong>the</strong> laboratory experimentation feasibility, it was suggested to<br />
test <strong>the</strong> specimens in ½ scale. Hence, some geometrical <strong>and</strong> mechanical reducing<br />
factors had to be applied to <strong>the</strong> section properties which include:<br />
• exterior geometrical dimensions <strong>of</strong> <strong>the</strong> concrete column (b <strong>and</strong> h);<br />
• amount <strong>of</strong> longitudinal reinforcing bars in <strong>the</strong> column (As,long);<br />
• amount <strong>of</strong> transverse reinforcing bars in <strong>the</strong> column (As, stirrup);<br />
• dimension <strong>of</strong> <strong>the</strong> steel pr<strong>of</strong>ile.<br />
Concerning <strong>the</strong> reduction <strong>of</strong> <strong>the</strong> steel pr<strong>of</strong>ile two different possibilities were taken<br />
into account. The steel pr<strong>of</strong>ile may be reduced ei<strong>the</strong>r in term <strong>of</strong> <strong>the</strong> cross area<br />
As,steel or in term <strong>of</strong> plastic modulus Wpl,steel. The first solution ensures that <strong>the</strong> axial