BURBANK REGIONAL INTERMODAL
TRANSPORTATION CENTER (BRITC) Owner: Glendale-Burbank-Pasadena Airport Authority
Design Build Team: McCarthy Building Companies / Saiful Bouquet Architect: PGAL
SEAOSC / SEAOC 2017 EXCELLENCE IN STRUCTURAL ENGINEERING AWARDS
PROJECT DESCRIPTION
� BRITC is the most advanced, high-tech transportation hub built in
California
� 300,000 sf Consolidated Rental Car Facility & Customer Service
Building
� Designed to withstand an earthquake larger than any California had
ever experienced
� Provided FEMA and the State of California a new Disaster
Command Center location to mobilize in the event of a major
earthquake or other disaster
SAP2000 Analysis
Computer Model
� Nonlinear Static Analysis with isolators
� Equivalent temperature loading calculated to represent creep, shrinkage and elastic shortening
� Two-Stage Analysis
� Stage 1: Creep, Shrinkage and Shortening from t = 0 to 4 months (Delay Strip Open)
� Stage 2: Creep & Shrinkage from t = 4 months to 5 years (Delay Strip Closed)
� Thermal Analysis: 50 deg. F Temperature Change
STRUCTURAL SYSTEM
� Gravity System
� Post-Tensioned Reinforced Concrete One-Way Floor structure w/
65’ x 65’ column bays and 19’ Story Height
� Steel Open Web Roof structure with capacity to support solar
arrays
� Lateral Force Resisting System
� Base-Isolation (82 Triple Friction Pendulum Isolator Bearings)
� Above Isolators: Special Concrete Moment Frames
� Below Isolators: Octagonal Cantilever Concrete Columns
� Roof: Special Concentric Braced Frames
� Foundations: Pile Caps with Driven Steel H-Piles
Base-Isolated BRITC Serves Dual Purpose asEmergency Response Nerve Center
“BRITC is essentially
the safest place to be
during an earthquake”
DESIGN CHALLENGES
� Ultra fast-tracked project. The entire design and peer review process
including nonlinear response history analysis completed in 4 months.
� Immediate Occupancy (IO) after a Maximum Considered Earthquake (MCE)
� Due to possible shrinkage, the project was built with a Delay Strip and
connected 4 months after completion
� Long Span Frame Structures
CREEP, SHRINKAGE & THERMAL ANALYSIS
Post-Tensioned Concrete BeamsIsolator Installation Isolator & Connector PlatesConcrete Columns Below Isolators
SEISMIC DESIGN CRITERIA (SET BY AIRPORT AUTHORITY)
� Creep, Shrinkage and Elastic Shortening per ACI 209R
SEISMIC PERFORMANCE OBJECTIVES
Building Performance Level
Ea
rth
qu
ak
e H
aza
rd L
eve
l
Collapse
PreventionLife SafetyImmediate
Occupancy
Frequent(43-yr EQ or
50% / 30yrs)
Rare(475-yr EQ or
10% / 50yrs)
Very Rare (2,475-yr EQ or
2% / 50yrs) Burbank RITC
Immediate Occupancy for a Maximum Considered Earthquake (MCE)
Inner Pendulum Motion(Frequent – 43-yr Earthquakes)
Lower Pendulum Motion(Rare – 475-yr Earthquakes)
Upper Pendulum Motion(Very Rare – 2,475-yr Earthquakes)
Main Concave
Cross Section of Triple
PendulumTM Bearing
Slider Concave
COMPONENT
ACTIONMATERIAL STRENGTHS RESISTANCE FACTOR (φ)
Concrete Beam Flexurefy = 1.1 fy,specified
f’c = 1.1 f’c,specified
φ = 1.0
Concrete Beam Shearfy = 1.0 fy,specified
f’c = 1.0 f’c,specified
φ = 1.0
Strong Column / Weak Beam
Evaluation
fy = 1.1 fy,specified
f’c = 1.1 f’c,specified
φ = 1.0
Structural Steel MembersFy = 1.1 Fy,specified
Fu = 1.1 Fu,specified
φ = 1.0
Elements Below
Isolation PlaneSpecified Material Strengths φ per code
STRUCTURAL ELEMENTS SEISMIC FORCES INTERSTORY DRIFT
Structural Elements Above
Isolation System
Essentially Elastic Response
based on MCE demands (R=1.0)2% of Story Height
Isolation System and
Structural Elements Below
Isolation System
Elastic Response based on MCE
demands divided by 0.8 (R=0.8)1.5% of Story Height
Delay Strip
N-S Moment Frames
E-W Moment Frames
Level 2 Floor Plan
SEISMIC ANALYSISA three-dimensional commercial nonlinear analysis software package, SAP2000, was used to investigate the
nonlinear seismic response of the RITC structure utilizing base isolation. The base isolators were modeled
using friction pendulum link elements available in the SAP2000 software package. Since SAP2000 does not
include a specific element that can consider the complex behavior of the triple friction pendulum isolators, a
two-component parallel model based on the work by Sarlis and Constantinou (2010) was used with properties
derived from the actual physical properties of the isolator units from the isolator manufacturer.