340 Bryant Office Building

Date of Completion:  April 2015

This building is a Non-Ductile Concrete Building. The engineering was performed originally by an outside consulting firm which later was revised to be the full seismic compliance designed by Matrix Seismic Group Corp. The construction was performed by our construction company, US Prime Contractor, Inc.

The first phase was installing shotcrete on the entire building at every level from inside.


In addition to seismic retrofitting, the large portion of concrete roof was converted to deck with accessible elevator. In order to take additional live load due to converting the roof to deck, the concrete deck was reinforced by using FRP to compensate for additional reinforcement which was required.

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A new mezzanine was installed on third floor as part of the tenant improvement.


The final phase was a concrete floor opening on third floor (approximately 14’ x 14’) to connect second to third floor internally for a single tenant occupying the building.



The job was performed and completed on time and budget.

First Presbyterian Church of Hollywood

Date of Completion:  March 2014

In 1909 the First Presbyterian Church of Hollywood (FPCH) was constructed as a Chapel in the Hollywood area.  In 1926 the main Church with its front bell tower was erected as a Steel Frame Building with Un-Reinforced Brick Masonry and concrete windows on all four sides.

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In 1953 a portion of the tower at roof level was repaired.

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In 1994 the Northridge Earthquake caused the tower to sustain some damages including the existing concrete windows.

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In 2012, FPCH hired Brandow and Johnston, Inc.  Structural Engineering Firm to design the main tower for seismic  reinforcement  and Steve Nuetzel Architect A.I.A. to restore the original concrete windows of this historical building.

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Matrix Seismic Group / US Prime Contractor, Inc. started the construction on November 2013 in two phases of seismic work, the revitalization and restoration of  the concrete windows by installing approximately 30,000 lbs of steel in the tower. The removal of 28,000 lbs of concrete from the four corners of the roof tower and replacing them with 1,500 lbs of hollow concrete. Additionally, all the concrete windows were repaired or replaced.

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 The construction was completed on time and within budget without additional cost.

Warfield Tower in San Francisco

Date of Completion: February 2014

The Warfield Tower and Theater is one of the most significant and historic buildings in the heart of the City of San Francisco. The building was built in 1921 as a six story theater with a ten story tower. The building is a Non-Ductile concrete shear wall in the short direction and a steel frame encased in concrete in the long direction.


The ten story tower was purchased and went thru a major remodeling and renovation beginning in early 2013.


One of the phases of remodeling was to add a cantilever concrete deck over the existing theater roof on the 7th floor  without adding a gravity load to the existing roof of the theater.


Matrix Seismic Group / US Prime Contractor, Inc. undertook the Design and Construction of this project in late 2012 in addition to the major structural renovation of the tower.


Convenant Presbytery Church of San Francisco

Date of Completion: December 2013

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The Covenant Presbytery Church of San Francisco, is located on 321 Taraval Street, San Francisco and was built in 1926. The tower was steel braced frame with stucco around it.

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 A Structural Engineer evaluated the tower’s integrity to resist any seismic forces during the event of a moderate earthquake. It was determined that the braces were not adequate and due to rain and the elements was beyond repair and that the tower should be removed.

photoMatrix Seismic Group / US Prime Contractor, Inc. was selected to remove the tower. The six story tower was removed and the building was restored on time and within budget without additional cost.