Project Details
This capstone explores how to design a mid-rise building on San Francisco’s soft clay soil that remains immediately occupiable after a major earthquake. Unlike standard “life safety” designs that allow significant damage, immediate occupancy requires that the building be plumb, functional, and safe to enter immediately after shaking stops.
DESIGN CRITERIA
The project designs for specific criteria:
| Criteria | Description |
| Building Height | 10 stories (mid-rise) — buildings at this height face the highest collapse risk |
| Location | San Francisco, CA — a “frequent earthquake zone” with a 1 in 72 (1.39%) annual chance of a major quake |
| Soil Condition | Soft clay — this soil type amplifies seismic shaking |
| Performance Goal | Immediate occupancy — the building must remain functional and collapse-free |
| Budget | No limitations — though cost-effective alternatives are noted where applicable |
METHODOLOGY AND SYSTEMS ANALYZED
The research began with foundational topics: earthquake mechanics, seismic building codes, cultural and regional design differences, and the history of earthquake engineering. From there, three core categories of seismic design were identified:
- Lateral-Force Resisting Systems: The primary structure/skeleton of the building that reduces forces
- Performance Enhancement Technologies: Isolators and dampers that reduce forces
- Foundations: the interface between building and soil
Each category was broken down into specific systems for detailed qualitative analysis.
Lateral-Force Resisting Systems
| Category | Systems |
| Moment-Resisting Frames (MRF) | Ordinary Moment Frames (OMF) Intermediate Moment Frames (IMF) Special Moment Frames (SMF) |
| Braced Frames | Cocentrically Braced Frames (CBF): X-Bracing (Cross Bracing), V Bracing/Chevron Bracing, K-Bracing, and Single Diagonal Bracing. Eccentrically Braced Frames (EBF) Buckling-Restrained Braced Frames (BRBF) |
| Shear Walls | Reinforced Concrete Shear Walls Steel-Plate Shear Walls Concrete Block/Masonry Shear Walls Plywood Shear Walls Mid-Ply Shear Walls Composite/Hybrid Shear Walls |
| Dual Systems | MRFs paired with either braced frames or shear walls. |
Performance Enforcement Technologies
| Category | Systems |
| Seismic Isolation | Elastomeric Bearings (Rubber-Based): Lead-Rubber Bearings (LRB), High Damping Rubber Bearings (HDRB), and Natural Rubber Bearings (NRB). Sliding/Friction Bearings: Friction Pendulum System (FPS) and Flat Sliding Bearings. |
| Passive Energy Dissipation (Dampers) | Viscous Fluid Damper Viscoelastic Solid Damper Metallic Damper Friction Damper |
Note: Seismic isolators combined with passive energy dissipation give a hybrid seismic protection system.
Foundations
- Mat Foundations
- Pile Foundations
- Isolated Footings
- Base Isolation (not explicitly a foundation type, but it is raising the building from its foundation)
EVALUATION CRITERIA
Each system was scored on a 1–5 scale using criteria tailored to its category. The highest-scoring systems were considered for the final design.
Lateral-Force Resisting Systems
- Ductility/Energy Dissipation
- Stiffness/Drift Control
- Residual Displacement Control
- Redundancy/Reliability
- Constructability/Soil Compatibility
- Cost/Efficiency
- Height Restrictions
- Seismic Isolation Compatibility
Performance Enforcement Technologies
- Flexibility (Period Elongation)–only for seismic isolators
- Damping (Energy Dissipation)
- Recentering Capability–only for seismic isolators
- Displacement Capability
- Vertical Load Capacity–only for seismic isolators
- Durability/Aging Resistance
- Constructability/Integration
- Cost/Efficiency
- Velocity vs. Displacement Dependence–only for dampers
- Stiffness Contribution—-only for dampers
- Force Reduction–only for dampers
Foundations
- Sediment Control
- Lateral Capacity
- Isolation Integration
- Liquefaction Resistance
- Soil-Structure Interaction
- Contructability
- Cost/Efficiency