BEHAVIOR AND ANALYSIS OF SHEAR RSISTANCE CAPACITY FOR SHEAR DOWELS CONNECTED R.C. JACKET WITH R.C FOUNDATION

Shear interface transfer between new an old concrete has a several factors that affect on the

value of its ultimate shear resistance. To study the behavior of shear dowels connected

reinforced concrete jacket with footing, an experimental program consists of two groups of

specimens were casted and tested. Group I consists of 16 push-off specimens representing 14

different cases of placing dowels were tested under static load. Two control specimens

without dowels were tested. Group II consists of 4 push-off specimens representing 4

different cases of placing dowels with smooth interfaces and strain gauges fixed on dowels

representing the position of all dowels were tested under static load., concrete of 250 kg/cm2 ,

350 kg/cm2 were casted for footings and jacket.

Different percentages of shear dowels in different surfaces of R.C. footing were studied

and test results showed that in placing dowels in surfaces A1 (column head surfaces) the

ultimate load increased and placing dowels in surfaces A2 and A3 (horizontal surface of

footing and vertical surfaces of footing) respectively decreased the displacement. When

dowels placed in three surfaces A1, A2, A3 together, the ultimate load was increased and

displacement was decreased. The actual effect of placing dowels in surfaces A2 and A3 did

not appeared bacause of high steel reinforcement ratio of jacket which resist the increament of

loading that was noticed from test results of group II.

A proposed modification of the Japanese code (JCI) formula was presented and

compared with the experimental test results and other formulae.