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Riverview Heights. Darren K. Howard Structural Option. Architectural Engineering Spring Thesis 2005 Advisor: Dr. Ali Memari. Riverview Heights. Darren K. Howard Structural Option. Table of Contents:. 1.0 Project Background 2.0 Problem Statement 3.0 Solution Overview
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Riverview Heights Darren K. HowardStructural Option Architectural Engineering Spring Thesis 2005 Advisor: Dr. Ali Memari
Riverview Heights Darren K. HowardStructural Option Table of Contents: 1.0 Project Background 2.0 Problem Statement 3.0 Solution Overview 4.0 Structural Redesign 5.0 Mechanical Issues 6.0 Acoustical Issues 7.0 Cost Estimates 8.0 Conclusions and Recommendations Acknowledgements Questions
Riverview Heights Darren K. HowardStructural Option 1.0 PROJECT BACKGROUND
Riverview Heights Darren K. HowardStructural Option • 1.0 Project Background: • Conshohocken, Pennsylvania • 4 apartment levels • 2 levels of partially underground parking
Riverview Heights Darren K. HowardStructural Option • 1.1 Apartment Structural Systems: • Bearing Walls: Wood stud walls • Floor: 20” deep, floor trusses • Lateral System: Wood Panel Shear Walls
Riverview Heights Darren K. HowardStructural Option • 1.1 Parking Structural Systems: • Elevated Two-Way concrete slab with drop panels • Top slab is a 11” thick “transfer slab” • “Transfer slab” picks up random bearing wall loads • Concrete columns send loads to spread footings
Riverview Heights Darren K. HowardStructural Option 2.0 PROBLEM STATEMENT
Riverview Heights Darren K. HowardStructural Option • 2.0 Problem Statement • Lumber is a renewable, but not unlimited resource • New building materials will eventually become necessary • Alternative materials and methods must be found
Riverview Heights Darren K. HowardStructural Option 3.0 SOLUTION OVERVIEW
Riverview Heights Darren K. HowardStructural Option • 3.0 Solution Overview • Cold-formed steel buildings are growing in popularity • Recyclable material • Not susceptible to termite damage • Will not burn or harbor mold • Will not rot, shrink, warp or split • Prices for cold-formed steel have been more stable than lumber • Construction methods are very similar to wood framing
Riverview Heights Darren K. HowardStructural Option 4.0 STRUCTURAL REDESIGN
Riverview Heights Darren K. HowardStructural Option • 4.0 Structural Redesign • Replace existing bearing walls with cold-formed studs • Replace wood floor trusses with cold-formed joists • Investigate the use of possible lateral systems: • Wood panel shear walls over cold-formed studs • Lateral strap bracing
Riverview Heights Darren K. HowardStructural Option 4.1 BEARING WALLS
Riverview Heights Darren K. HowardStructural Option • 4.1 Bearing Wall Redesign • Existing bearing walls and unit separation walls:
Riverview Heights Darren K. HowardStructural Option • 4.1 Bearing Wall Redesign • Design Considerations: • Replace existing unit separation walls with a single cold-formed stud wall • Set studs at a spacing of 24” o.c. rather than 16” o.c.
Riverview Heights Darren K. HowardStructural Option • 4.1 Bearing Wall Redesign • Redesigned Walls: • Unit separation walls: 6” wide studs @ 24” o.c. • Interior bearing walls: 3-5/8” studs @ 24” o.c. • Gauge of stud varies from floor to floor
Riverview Heights Darren K. HowardStructural Option 4.1 Bearing Wall Redesign Unit Separation Walls
Riverview Heights Darren K. HowardStructural Option 4.1 Bearing Wall Redesign Interior Unit Bearing Walls
Riverview Heights Darren K. HowardStructural Option 4.2 FLOOR SYSTEM
Riverview Heights Darren K. HowardStructural Option • 4.2 Floor System Redesign • Existing Floor: 16’ to 25’ interior spans
Riverview Heights Darren K. HowardStructural Option • 4.2 Floor System Redesign • Design considerations: • Cold-formed steel joists should require less depth • This will add additional floor-to-floor height in units
Riverview Heights Darren K. HowardStructural Option • 4.2 Floor System Redesign • Redesigned Joists: 14j10 Marino/Ware Joists • 14” deep, 10 gauge joists @ 24” o.c. • Allowable p.l.f. = 130 p.l.f. ( d < L/360) • An additional 6” of floor-to-floor height is achieved
Riverview Heights Darren K. HowardStructural Option 4.3 LATERAL RESISTANCE
Riverview Heights Darren K. HowardStructural Option • 4.3 Lateral System Redesign • Existing Lateral System: Wood Shear Panel Walls
Riverview Heights Darren K. HowardStructural Option • 4.3 Lateral System Redesign • Design Considerations:
Riverview Heights Darren K. HowardStructural Option • 4.3.1 Lateral System Redesign • Alternative #1: Wood shear panels over cold-formed studs • Greater strength = fewer shear walls required # of Shear Walls Required
Riverview Heights Darren K. HowardStructural Option • 4.3.2 Lateral System Redesign • Alternative #2: Lateral Strap Bracing
Riverview Heights Darren K. HowardStructural Option • 4.3.2 Lateral System Redesign • Alternative #2: Lateral Strap Bracing • STAAD frame model of tension braces
Riverview Heights Darren K. HowardStructural Option 4.3.2 Lateral System Redesign
Riverview Heights Darren K. HowardStructural Option 5.0 MECHANICAL
Riverview Heights Darren K. HowardStructural Option • 5.0 Mechanical Issue • Major disadvantage of cold-formed steel • Thermal conductivity HOT COLD
Riverview Heights Darren K. HowardStructural Option • 5.0 Mechanical Issue • Add a thermal break between the exterior and interior space • An additional layer of 1” rigid insulation must be installed
Riverview Heights Darren K. HowardStructural Option 5.0 Mechanical Issue
Riverview Heights Darren K. HowardStructural Option 6.0 ACOUSTICS
Riverview Heights Darren K. HowardStructural Option • 6.0 Acoustics • Cold-formed studs have lower acoustical properties • Riverview Heights was designed as an “average” site • Unit separation walls and floors need to meet an STC rating of 52
Riverview Heights Darren K. HowardStructural Option • 6.0 Acoustics • An additional 5/8” of gypsum is required on both sides of walls to meet acoustical requirements • Existing wood floor trusses and the redesigned joists required resilient channels on the ceiling side
Riverview Heights Darren K. HowardStructural Option • 6.0 Acoustics
Riverview Heights Darren K. HowardStructural Option 7.0 COST ESTIMATES
Riverview Heights Darren K. HowardStructural Option • 7.0 Cost Estimates • Estimate of Wood Framing
Riverview Heights Darren K. HowardStructural Option • 7.0 Cost Estimates • Estimate of Cold-Formed Framing
Riverview Heights Darren K. HowardStructural Option • 7.0 Cost Estimates • Cold-Formed Framing Additional Costs
Riverview Heights Darren K. HowardStructural Option • 7.0 Cost Estimates • Total Costs • CF joists are more than twice the cost of wood floor trusses!!
Riverview Heights Darren K. HowardStructural Option • 7.0 Cost Estimates • Total Costs without Floor Systems
Riverview Heights Darren K. HowardStructural Option CONCLUSIONS AND RECOMMENDATIONS
Riverview Heights Darren K. HowardStructural Option • 8.0 Conclusions and Recommendations • Cold-formed framing is a viable solution if the redesigned floor framing is not included • Cost of the cold-formed floor framing was more than twice the cost of wood trusses • Cold-formed framing used less material in walls and in lateral systems • Using less material translated into lower costs • Promising conclusion as the need for alternative building materials becomes greater in the next century
Riverview Heights Darren K. HowardStructural Option • Acknowledgements • My family and friends • A.E. faculty • Staff of Cates Engineering • Trammel Crow Residential • Minno & Wasko Architects • Marino/Ware • Images courtesy of Marino/Ware, Cates Engineering, and Minno & Wasko Architects
Riverview Heights Darren K. HowardStructural Option Questions?