Lumen West LA

The development formerly known as the Trident Center was originally constructed in the 1980’s as a pair of independent 10-story towers totaling 300,000 square feet of Class A office space above 2 levels of subgrade parking. The existing structure consisted of concrete over metal deck flooring supported on steel wide flange beams spanning to steel wide flange columns. The lateral system consisted of pre-Northridge moment frame connections. The existing foundation system consisted of pile caps supported by 40 ft deep drilled piers.

The renovation adds 115,000 square feet of new space where all elevated floors are extended at the corners of the floor plate, and bridges connecting the two towers are added at multiple levels. The added area and mass required the building to undergo a full seismic retrofit. The result was the first high-rise steel moment frame building to be seismically retrofitted using ASCE 41 in the City of Los Angeles. As the structural engineer of record, JAMA used ASCE 41 Tier 3 linear dynamic procedures to evaluate and design the retrofit to meet the required performance criteria without compromising the architectural intent.  

Building Revit Model 

The vision for the building was to provide a natural light-infused workplace to enhance health, wellness and collaboration. To accomplish this, the original precast concrete façade was removed and the building was entirely reclad in glass. The seismic retrofit, therefore, could not impact the exterior and was limited to within the interior of the building. Rather than adding braces or dampers that would disrupt the perimeter glazing, the retrofit focused on strengthening the existing moment frame connections using a combination of bottom haunches and welded web improved WUF connections to improve ductility. 

The full structural scope of the renovation and seismic retrofit included the following: 

• Renovation of the recreation deck 
• New outdoor landscaped grand stair connecting the recreation deck to street level 

Expansion of 4-story structure towards Olympic Boulevard with extra private outdoor space above 

• Removal of the original precast façade and recladding the entire perimeter with new glass  
• Addition of a new penthouse story on top of each tower 
• Squaring the corners of the floorplates to add new floor area  
• Adding interconnecting bridges at alternating floor levels to connect the two towers 
• New pile caps and drilled piers at new columns 
• Strengthening of existing basement concrete shearwalls with shotcrete 

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