This project was motivated by the owner's desire to
seismically upgrade the Rivera Library Building on the
campus of the University of California at Riverside. A
photograph of this four story building is shown in Fig. 2.
This building has a 41 73 m (135 240 ft.) footprint and
throughout the exterior walls are clad by over 300 reinforced
concrete panels. The cross-section of a typical panel is shown
in Fig. 3(a).
At the middle the panel is 165 mm (6.5 in.) thick, and is 102
mm ( 4 in.) thick along the longitudinal edges. For
experimental purposes, the thickness of a panel was simplified
to be 127 mm (5 in.) thick throughout, Fig. 3(b), resulting in
an equivalent shear capacity as in the actual building. The
height of the experimental panel was reduced from the design
height of 4.0 m (13 ft.) to 3.5 m (11.5 ft.) for ease of
installation into the test frame and the clear height remained
the same as in the prototype. A photograph of the test panel
is shown in Fig. 4.
It was cast using lightweight concrete with the ultimate
strength of 28 MPa (4 ksi). A general view of the cladding
panel in the test frame is shown in Fig. 5. The essential
features of the panel attachments to the test frame consist of
three elements: (a) bottom supports, (b) three energy
dissipating devices at the top, and (c) hydraulic load actuator
for applying cyclic load shown on the right near the top of the
A more detailed illustration of the bottom supports is shown
in Fig. 6. The two vertical steel assemblies are largely for
resisting the overturning force caused by the application of the
inplane horizontal force at the top of the panel by the actuator.
The horizontal plate at the bottom is mainly for resisting shear.
Note that there were 32-14 mm (9/16 in.) diameter holes for
attaching the wall panel to the steel details. In that regard, the
initially specified Hilti Kwik Anchor Bolts, Fig. 7, were found
to be inadequate.
As during the application of the cyclic load by the actuator, an
unpermissible movement between the wall and the steel
details took place. This can be readily explained by noting the
following. The expansion end of a bolt had to pass through 14
mm (9/16 in.) diameter holes in the steel plates, requiring the
same size of holes in the concrete wall. As a result, beyond
the bolt expansion end toward the bolt nut, a void in the shape
of an annulus was formed allowing the bolt shank to move
freely back and forth. By changing the bolts to a
Hilti Hit HY-150 type, Fig. 8, and injecting epoxy around the bolts, the
bolts remained solidly embedded during repeated tests.
For both sizes of bolts the drilled bolt-holes were 57 mm (2.25 in.) deep. When the bolt sizes were changed, the panel was turned upside down and turned around through 90o in order to attach the steel details to the unmarred side of the panel.
The basic detail of an energy dissipating device near the top of
the wall is shown in Fig. 9.
The test wall made-up in the above manner was then extensively instrumented particularly for measuring displacements.