Performance of coupling beams with openings exposed to cyclic loading

Abstract EN

The performance of coupling beams under cyclic loadings is evaluated when theyhave openings with different configuration.

The study is performed throughexperimental examination on four reduced scale coupling beams.

The testing is donein the Concrete Laboratory at the Housing and Building National Research Center, Cairo, Egypt.

Square openings are constructed on three specimens with differentconfigurations whereas the fourth specimen kept without openings for thecomparison matter.

Two openings are fabricated at top and bottom of the diagonalbars in one beam specimen.

Another specimen contains two openings at left and rightof the diagonal bars.

The last specimen has four square openings placed at top-bottomand left-right of the diagonal bars of the coupling beam.

The yield and ultimate tensilestrength of the reinforcement steel bars are 510 and 720 MPa, respectively withelastic modulus of 200 GPa.

The concrete characteristic strength is 38 MPa.

Allspecimens were tested under laterally cyclic loading to simulate the subjected loadson coupled shear walls.

A special complicated setup is utilized for that issue.

Theresults are recorded during testing and at the end of each cycle.

The forcedeformationrelationships are recorded and their corresponding hysteresis loops areplotted.

The cracks patterns are also marked and recorded.

From the obtained results, one may observe that, in case of using two openings located at right and left (near theshear walls), the stiffness of the coupling beam is slightly decreased.

The couplingbeams stiffness is decreased by ~8.5% for the other pattern of two openings and by~13.5% in case of using four openings.