The Pit–In Memoriam

The Pit–In Memoriam

May 22, 2016 — May 20, 2018

Parking Lot Architecture

Loma Linda University Medical Center The Way it Was

circa 2005

With the turn of the twenty-first century fresh in our minds, Loma Linda University was looking forward to celebrating its 100th-anniversary in the summer of 2005. Construction on two new hospitals were the whispered talk of planning committees, but to those whose every day lives were consumed  by the rigors of the campus such an event was not on their radar. Where the pit would be dug one day, a parking lot properly groomed with hedges, flowering bushes, Mexican Fan Palm Trees, rose bushes, and other colorful flowers delighted the senses. As this photo shows, the parking lot achitecure was an oasis in the asphalt jungle.

The Life Cycle of the Pit: From Grade to

Sub Grade and Back to Grade

The Foot Print for two Hospitals: Two New Towers of Healing

Introduction

For purposes of this blog the pit is referred to as the bottom, the foundation, the concrete that is designed by the architects and structural engineers to hold the building. The shoring walls, the foundation walls along with the connecting rebar are anchored by long horizontal soil nails and vertical steel pilings that are sunk some 90-feet in the ground to retain the soil from collapsing on to the foundation and the building structure. These steps are covered elsewhere on the website. To accomplish the goal of reaching sub grade and constructing the foundation took the following:

1. To excavate the Pit: It took 110,000 yards of soil. To put it another way: 7,857 truck loads holding 14 yards of soil each.

2. 1,400 yards of concrete poured for the four-inch rat slab; 140 truck loads of concrete at 10 yards per truck.

3. To reinforce the the foundation with rebar it took 5.1 million pounds (2,550 tons) of steel. Laying the rebar end-to-end would span some 200 miles.

4. It took 15,230 yards of concrete to complete the four-foot foundation floor. At 10 yards a truck, it took 1,523 truck loads of concrete.

5. 126 base isolators were anchored to the foundation.

6. 98 damper pedestals were anchored to the foundation.

7. 196 dampers (2 for each pedestal).

Some eleven years after the above photo was taken, sometime around February of 2015, the heavy machines of progress and the make ready crew cut down the trees, uprooted the shrubbery, trampled the flowers, ripped out the asphalt, pulverized the concrete an otherwise leveled the ground. Approximately three-years later the stately Mexican Fan Palm Trees reappeared as steel columns. No one likes to read an In Memoriam tome, nor attend a four-hour funeral so this blog will spare the details and will only represent the highlights of the disappearing pit. The details can be found in other sections of this website.

On Sunday, May 22, 2016, Ground breaking was held, out on a newly paved asphalt lot, which would later serve as the “yard” for equipment, steel and other construction necessities only one could imagine at the time. The date of the Ground Breaking will serve as the date the pit was inaugurated.

By early July, the pit was defined as illustrated in this photo taken from the southeast corner.

The Pit Yawns Wide

As If To Devour The Existing Hospitals

A so, it came to pass after approximately six months of excavating, the crew reached grade. By December 14, the three elevator pits were being excavated and compacted. At the east wall, just out of the frame, a small section where the ramp had been, two tiers of the shoring wall had to be sprayed with shot crete.

Eight Thumbnails Depicting

the Major Elements of the Foundation at the Bottom of the Pit

Electrical and telecommunication ducting were laid in trenches, covered in concrete, and then soil  compacted to grade.

Eight (8) rebar caissons were lowered into holes that were drilled 45-feet below grade. The caissons will serve as supports for the wider cap slabs that will be poured on top of the foundation walls.

After reaching sub grade a four-inch “Rat Slab”
was poured to prevent wind, rain, and vermin from
disturbing the final grade. In addition, the Rat Slab
will serve as the base for the rebar.

Beginning at the west end of the pit, the rod busters began to layout and tie the rebar into place. In addition to laying the rebar, they would lower four sleeves at the four corners of the base isolators. These sleeves tie into the seismic protection system,

The foundation concrete was poured in sections over three dates: March 25, 2017; April 29, 2017; and May 20, 2017. These pours were an important phase of the project. One of the workers remarked that: “Well, when this foundation pour is over, we won’t have to play in the dirt anymore.”

May 21, 2017: After an all-night concrete pour, the long awaited four-foot thick concrete floor was joined spanning the width and length of the pit. It is from this foundation floor that the steel skeleton will rise above grade to the full measure as designed by the architects.

Embedded in the Foundation are two very important (must have) components of the seismic protection system: The Base Isolators and the Damper Pedestals.

Base Isolator in formation, terracotta soldier fashion: The round isolators are bolted to the bases, which are bolted to the embedded anchors. It is on these base isolators that the gigantic spline beams will rest.

One of the damper pedestals (center), on which a welder is securing a damper bracket to the pedestal. Each pedestal as two dampers: one end attaches to a spline beam node and the other end is anchored to a pedestal bracket. Each damper is 30-feet long and weighs 6,000-pounds. At the lower right is a base isolator, on which the node of the spline beam is bolted.

The four corners of the pit before the steel.

With a beautiful sunset seemingly giving an evening blessing over the Children’s Hospital and Medical Center, the pit awaits the phase of progress: The Steel.

By December 19, 2017, gigantic steel spline beams began to raise the level of the pit toward grade and above.

Four corners as the steel rises above grade: On Monday, May 21, 2018, the pit succumbed to the weight of the steel, the ironworkers wrench, and the welder’s torch. What was the pit is now a memory: All floors, with decking, have reached the original grade or beyond. Although the pit is out of sight, it is doing its job for it holds all of the seismic reduction elements (dampers and isolators) along with 20-percent of the weight of the building in structural steel on the first layer only.  The next phases will be the topping off ceremony for the podium (date to be determined), the topping off ceremony for the Children’s Hospital (date to be determined), the topping off of the Adult Hospital (date to be determined). The final ceremony will be the ribbon cutting sometime in December 2019 (date and time to be determined).

~ Finis ~