Big Beam Competition

The Fabrication

Laying the formwork for the beam.

Getting forms ready.

Layout of reinforcing steel.

Forming up.

Work on reinforcing steel.

Rebar with foam insert.

Form for I-section.  Foam maintained full box section at center of beam to resist moment.

Another look at the formwork.

Insertion of rebar into form.

Rebar in forms.

Reinforcing steel in forms, preparing for mix.

Two formed beams:  one box beam, one I-shape.

Another shot of formwork.

Preparing to pour.

Mixing hopper.

Concrete mix in hopper.

The mix.

Pouring concrete into forms.

Mike overseeing proper techniques.

Freshly poured beams.

The Testing

The setup of the reaction frame.  Two beams to be tested:  one I-beam and a box beam, both prestressed concrete.

Another view of the setup before testing.

Getting Enerpac hydraulic cylinder into place.  The I-beam was tested first.

Each beam rested on elastomeric bearing pads.  They were 15 feet in length with a clearspan of 14'6".

Mike and Lisa setting up the instruments to measure vertical displacement.

Enerpac in place, ready to commence testing.  The jack has a maximum capacity of 100 kips.

A view of the setup just before testing.

Another shot of the test setup.

Mike, Bryan, and Nate, all members of the Big Beam Team.

Dr. Howard checking alignment of jack.

In the testing phase.

Load being applied........

Close-up of the the test beam during testing.

Displacement occurring, cracks evident and marked.

Mike working his magic with the camcorder.

Adjustment of the gauges.  Cracks propagating, deformation obvious.

Proliferation of cracks, more deformation.

Still testing.

Overall view.  Deformation easily seen.

More load......

More load........

A lot of displacement evident.  Compression in top of beam causes chunks of concrete to fly off, can be seen around beam.

Failure of I-beam.

Removal of testing equipment from I-beam.

Failed concrete at center of I-beam.

Close-up of failure, bent compressive reinforcing steel showing.

Another close-up with chunk of expelled concrete:  sheared through aggregate.  Good mix design.

Next, the box beam.  Load applied, cracks marked.

Propagation of cracks.

Deflection of box beam during testing.  Yes, that's Dave Leake in the background.

More deformation, failure of concrete in tension.

Complete failure of beam, removal of testing equipment.  Reinforcing steel exposed.

Removal of jack from loading frame.

Two beams, side-by-side.  Box beam mix also sheared aggregate:  good mix.

Close-up of box beam failure, bent rebar.

Close-up of both beams, aggregate sheared.