Structural Retrofit - Overview
Seismic Retrofit and Historical Restoration projects are ideally suited for the use of Shotcrete. Superior has pioneered the use of Shotcrete as a cost saving and time saving alternative to CIP (Cast in Place) concrete for the reinforcement of existing commercial and civil structures.
The Shotcrete Advantage is ideal for retrofit and restoration projects because it can be applied against existing walls to strengthen them or against one-sided forms to construct new walls. The use of Shotcrete eliminates the necessity of a one-side form against existing walls, which is very expensive, and a two-side form for new freestanding CIP walls. Additional cost savings are achieved because Shotcrete is applied from the bottom of the wall up, eliminating the necessity to core and pour concrete through the ceiling above the wall.
Seismic Retrofit: Since the 1989 San Francisco Earthquake and the 1994 Northridge Earthquake, Superior has led the industry in the application of Shotcrete on seismic retrofit projects in California. Superior is a full service construction company, whose scope of work can include drilling and coring dowel holes, furnishing and installing epoxy set reinforcing steel dowels, reinforcing steel and the forms required for the Shotcrete work. Additionally, Superior can provide all the services necessary to strengthen the existing footings or provide new footings to include excavation, reinforcement, forms, Shotcrete and or concrete. In addition to preventative seismic work, we also install Shotcrete on a remedial basis to structurally rehabilitate buildings that have sustained major earthquake damage. The use of Shotcrete does accelerate completion of the project.
Historical Restoration: While many historical restorations involve seismic retrofit, these projects present the additional challenge of preserving the integrity of the original architectural details and finishes. The use of Shotcrete does provide wider latitude for the preservation of existing architectural details than CIP concrete. Also, existing concrete finishes can be duplicated on the surface finish of the new Shotcrete.
Los Angeles City Hall: Los Angeles, California
The initial seismic retrofit design for the Los Angeles City Hall specified the use of Shotcrete for the first four floors and CIP concrete for floors five through twenty-two. Based on Superior's reputation and its performance on the project, the use of Shotcrete was proposed and accepted for use to the twenty-second floor. New shear wall construction and the strengthening of existing walls resulted in the placement of over 3,500 cubic yards of structural Shotcrete. This eliminated the conventional 2-sided forms for the shear walls and 1-sided forms for the increased thickness of the existing walls. The Superior team played a major role in saving time and money to complete this very challenging retrofit project.
State Capital Building: Sacramento, California
Home to the California Legislature since 1869, the State Capitol Building in Sacramento was preserved and strengthened by the application of Shotcrete on the interior of the building. Over 5,000 cubic yards of reinforced 18" to 30" thick Shotcrete were applied against the existing unreinforced brick walls that varied in thickness from 5' thick in the basement to 1' 6" thick at the roof. This historical restoration brought the Capitol building into compliance with earthquake building codes while retaining the architectural integrity of the original exterior. This California historic landmark is also listed in the National Registry of Historic Places.
San Buenaventura City Hall: Ventura, California
Originally built in 1912 as the Ventura County Courthouse, this California historical landmark is also listed in the National Register of Historic Places. The interior of San Buenaventura City Hall was completely seismically strengthened and restored to code with innovative Shotcrete solutions, while preserving the original neo-classical style facade.
Plaza Del Cultura y Arte: Los Angeles, California
This challenging historical restoration in downtown Los Angeles required a host of innovative techniques to preserve the unreinforced brick and mortar exterior of this old five story building while providing the necessary seismic and code upgrades. The solution was essentially to build a new building within the old. A member of our Family of Companies served as the general contactor on this project and Superior brought its expertise and the Shotcrete Advantage to this difficult restoration.
A new foundation consisting of grade beams and foundation pads supported by newly installed micro piles was constructed below the existing building to support the added mass of the Shotcrete reinforced building. All the exterior brick walls were reinforced with Shotcrete walls from the basement to the top of the roof parapet. Superior's scope of work included surface preparation, drill and bond epoxy reinforcing steel dowels, reinforcing steel, block out forms for doors and windows in addition to the Shotcrete.
The use of Shotcrete resulted in a considerable savings of time and money compared to the costs anticipated for cast in place concrete.
UCSB "San rafael" Residence Halls: Santa Barbara, California
The seismic retrofit of both the North and South 10-story structures had to be completed one at a time in series during an extremely tight 12-month schedule. Initially, Shotcrete was only designed to be used for the 6-inch thick overlay of existing walls above the 3rd floor. The thicker walls below the 4th floor and the full building height exterior pilaster columns were designed to be CIP concrete.
The General Contractor, who had used Superior's services on many projects and was familiar with the time and cost saving attributes of Shotcrete, proposed the use of Shotcrete for all the concrete walls and pilasters above the foundations. The Shotcrete alternative was approved bringing the project in on time and avoiding a liquidated damages penalty.
Shotcrete was the perfect choice for strengthening the interior walls as well as a cost effective choice for construction of the structural pilasters on the exterior of the buildings.
