Elements of the Foundation: The Earthquake Damper System

Various sizes of rebar are now being tied together in the center elevator pit, which when completed will include all the elements to strengthen the four-foot foundation base.

xx-xx-17 – X

This book contains the detailed plans for the structural foundation of the Loma Linda University hospitals. The drawings within these pages

come to life as each piece of rebar and other foundation elements are laid down on the rat slab.

xx-xx-17 – X

With approximately three-quarters of the rat slab poured, work can begin on laying the steel rebar for the four-foot foundation base. The iron workers will begin in the southwest corner of the pit and move along the west shoring wall and out toward the center of the pit. There are several layers of differently sized rebar that will reinforce the foundation floor. This 01.28.2017 tower view depicts the beginning stages of this important construction step.

02-10-17 – X

It is all about technology. Using a total station, Alex (left) is laying out the grid lines for the
rebar. The screen, at the right, displays the location of the grid lines as well as the position of the
isolator bases and the damper system components. Using this form of technology saves time, money, and is more accurate.

xx-xx-17 – X

Along the western wall, the first lengths of rebar are being laid out on the Dobie (blocks).

xx-xx-17 – X

After the first layer section of is laid, the isolator frame legs are placed. One-hundred and twenty-six frames on which four sleeves will rest at each

corner must be constructed to fit with all the foundation elements prior to the concrete pour.

xx-xx-17 – X

The isolator frames which hold the isolator sleeves are being attached to the legs. After all of the elements of the frame are bolted together, the frame must be anchored to the rat slab, and leveled.

02-24-17 – X

Aligning and leveling the isolator frame.

Isolator pin sleeves await placement on the frames. Due to the structural load, each base must support, the pin sleeves differ in circumference and can weigh anywhere from 600 to 900 pounds.

02-16-17 – X

This photo depicts isolator pin sleeves that have four (4) different circumferences. The smallest in circumference are to the left with the largest to the right. Each of the different circumferences is selected from one (1) of the six (6) types of isolator pin sleeves. The structural load of the building determines the location of each of the 126 earthquake damper system bases. Once the placement is established, the engineers will determine the size and type of isolator pin sleeves required to support each isolator base, which has been engineered to meet the building load.

02-24-17 – X

The crane is hoisting the straps which will lift four pin sleeves to be placed on an isolator frames.

02-24-17 – X

Attaching the straps to the pin sleeves.

xx-xx-xx – X

With the frames complete, preparation is underway to lift four pin sleeves onto the frame. To maintain a proper balance, the four pin sleeves are

lowered on the frame at the same time.

xx-xx-xx – X

Lifting the pin sleeves over the rebar.

xx-xx-xx – X

Four (4) rodbusters carefully guide the pin sleeves onto the frame.

xx-xx-xx – X

Setting the pin sleeves onto the frame.

xx-xx-xx – X

Before the hoisting straps are removed, the pin sleeves are braced and bolted to the frame after which lateral bracing is attached to each sleeve

to align and stabilize the sleeves.

xx-xx-xx – X

The anchored pin sleeves with bracing as viewed from the southwest shoring wall.

xx-xx-xx – X

A closeup of the isolator pin sleeves, aligned, leveled, anchored and braced to the frame.

xx-xx-xx – X

THE REBAR GRID IS BUILT UP IN THE CENTER ELEVATOR PIT

Far left: checking the gridlines. Right: the layout begins.

Left: the second layer

xx-xx-xx – X

Like the Chinese Terracotta Soldiers, the isolator Pin sleeves stand in formation in the center elevator pit. In a few days, the sleeves will be enclosed by other layers of rebar at which time the base plates will be properly aligned and the temporary lateral braces will be attached.

xx-xx-xx – X

Checking the plans for what goes next. The sleeves in the center elevator pit are now surrounded by rebar.

xx-xx-xx – X

A rod buster walking the rebar grid.

xx-xx-xx – X

Working between the rebar layers. The top of the wooden form delineates the floor level for the southwest elevator pit foundation.

xx-xx-xx – X

In the center elevator pit. . . .Thigh deep in rebar. . . .Tying one piece at a time.

12-05-16 – X

A few months before the isolator frames would be installed, two engineers were holed up in a warehouse, about three miles north of the construction

site, fabricating a mockup of an isolator frame and lateral bracing. The actual assembly as seen in the photo below replicates the mockup.

xx-xx-xx – X

With the isolator frames properly braced and anchored, the center elevator pit is now ready for the concrete pour.

xx-xx-xx – X

The isolator pin sleeves are now surrounded by rebar. When dry, the concrete will be level with the top of the pin sleeve.

03-06-17 – X

After the pin sleeves have been placed on the isolator frame and all of the horizontal rebar has been properly placed per the specs, the base plates, which will support the isolator base will be installed. The specs call for eight (8) isolator plates for each isolator base. Per the specs, the size of the isolator base determines the size and placement of the base plates.

Temporary lateral braces

xx-xx-xx – X

A view from above of all of the elements that make up the isolator support system, which will be embedded into the four-foot concrete foundation. Once the concrete is poured the lateral bracing will be removed. The eight base plates supported by Richmond Dowels will serve as reinforced pedestal footings for the isolator base, which will be anchored to the steel base plates.

12.05.16 – X

In addition, the engineers fabricated a mockup of an isolator base with lateral frames surrounded by rebar (PVC pipe) per the specs.

xx-xx-xx – X

A top view of an Isolator Base support sections.

xx-xx-xx – X

This is a mockup of one of 126 isolator bases that will be anchored above the isolator pin sleeves after the foundation has been poured.

02.03.17 – X

Damper Template used to mark where the dampers are to be placed.

01.31.17 – X

With the use of the template, the damper outline along with the placement of the Richmond Dowels is spray-painted onto the concrete.

03.08.17 – X

The Richmond Dowels are being placed per the specs as outlined by the template. The bottom section (embed) of the dowels will be anchored by the concrete

foundation. After a heavy top damper plate is affixed to the top of the dowels, the system will be formed and encased in concrete, which will complete

the damper pedestal.

04.30.17 – X

Notice the two rows of Richmond Dowels, which are now encased in the concrete foundation.

03.27.17 – X

A top view of Richmond Dowels embedded in the concrete foundation.

05.23.17 – X

An inverted metal plate, which is the top of the embedded damper pedestal.

05.24.17 – X

A  top metal damper plate weighing approximately 1,500 lbs. rests on top of the Richmond Dowels which are embedded into the concrete. The actual

assembly of all fifty-two damper plates will begin in a couple of weeks.

06.01.17 – X Video

The top metal damper plates are being lowered from grade by crane and stacked around the pit slab in readiness for assembly of the damper system pedestals.

06.06.17 – X 

Martin is making the rounds checking the center of all of the isolator pen sleeves.