800 North Glebe Arlington, VA

800 North GlebeArlington, VA

Ryan Johnson - Structural OptionAE Senior Thesis – 2010

OUTLINE

•Project Info

•Existing Structure

•Project Goals

•Structural Depth

•Architectural Breadth

•Construction Breadth

•Comparison and Conclusion

•Questions and Comments

General Building Data

• Location: Arlington, VA

• Occupancy Type: Mixed-Use Office

• Distinctive Architectural Features

• Building Setbacks At Levels 4,6 And 8

•Project Info•Existing Structure

•Project Goals

•Structural Depth




3 Below Grade Parking Levels 1 Level Retail On Ground Level 9 Levels Of Offices

•Project Info•Existing Structure

•Project Goals

•Structural Depth




EXISTING STRUCTURE

General Building Data•Size: 316,000 SF

•Completion Date: 2011

•Estimated Project Cost: $62 Million

EXISTING STRUCTURE

•Project Info

•Existing Structure•Project Goals

•Structural Depth




Existing Structure•Column Foundations Range In Size From 4’-0” Up

To 14’-0”

• Caissons Supporting On-grade Columns

• 6’-0” Thick Mat Foundation Supporting Shearwalls

• 12” Foundation Wall Around Parking Substructure

•Project Info


•Structural Depth



•Comparison and Conclusion CAISONS

N

Existing Structure•Post-tensioned Girders With 9” Thick One-Way Slab

• 10.5” Two-way Slabs Used For Building Stepouts

• Two 12” Think “C” Shaped Shear Walls At The Building’s Core

•Project Info


•Structural Depth




Y

X

PROJECT GOALS

•Project Info


•Structural Depth




•Project Info


•Project Goals•Structural Depth




Project Goals• Uniform Slab Type And Thickness

• Uniform Column Sizes

• Reduce Lateral loads Carried By The Shearwalls

• Determine Affects On Floor Plans

• Compare Sequencing And Cost

rgj5003

Reduce the lateral load carried by the central core shear walls title the goals as structural and "effects of structural"

STRUCTURAL DEPTH

•Project Info


•Project Goals

•Structural Depth•Architectural Breadth



•Project Info


•Project Goals




Structural Depth

Design Process

1. Initial Plan Layout

2. Slab Design

3. Lateral System Design

rgj5003

Done to allow for flat plate systemRedesign done for tech 2 and other system able to be implementedInitial column sizing based upon reduction in tributary area

•Project Info


•Project Goals




Slab Design

• Slab Type And Thickness

• Direction Of Banded Tendons

• Tendon Stresses Altered To Account For Opening And Nonuniform Slab Edges

d =

30’ x 12” 45 = 8” two-way post-

tensioned

•Project Info


•Project Goals




Y - Direction

• Distributed Tendons • 4 7-wire Strands Per Tendon• Uniformly Spaced To Allow For 250 psi Minimum

Precompression Stress

X - Direction

• Tendons Banded Along Column Strip• 25 7-wire Strands Per Tendon Grouping• 650 Kips Average Tendon Forces

•Project Info


•Project Goals




Immediate Load Deflection = Service LC – (Dead +Balanced)

Time Dependent Deflection = Long Term LC–(Dead + Balanced)

•Project Info


•Project Goals




Lateral System DesignInitial Design

•Uniform R-value For Both Directions (R=6)

Initial Design• Shear wall core

•Project Info


•Project Goals




Lateral System DesignRedesign

•Different R-value Per Direction (Rx = 5,Ry = 5.5)•Ordinary Reinforced Shearwall & Duel System

• PT Flat Plate Slabs Used In LFRS Not In Code

Redesign•Shear Wall Core•Concrete Moment Frame Included In Y - Direction

rgj5003

new included sublevel and restraintsLoad determination based upon base shearsASCE 7-05 Table 12.2-1North-South Ordinary reinforced concrete shear walls Rx = 5 East-West Dual systems with intermediate moment frames capable of resisting at least 25% of prescribed seismic forces Ry = 5.5

rgj5003

Gross Member Properties For Slab-Beams And Columns Columns And Shears Wall Moment S Of Inertia Were Reduced To 0.7Ig. Beam Elements Included A 0.5 Rigid End Offset Multiplier Shear Caps Included For Flexural Stiffness Bottom Bonded Reinforcement Provided Influences Of Tendon Layout

•Project Info


•Project Goals




Lateral System Design

System Comparison

Loading Condition:• Wind Load Case 1 Controlled Both Designs

Displacement• Max X: 53% Reduction• Max Y: 27% Reduction

Story Drift• Max X: 45% Reduction• Max Y: 20% Reduction

•Project Info


•Project Goals




Column Design

EXISTING STRUCTURE

•Project Info


•Project Goals




DEPTH CONCLUSION• Uniform Slab Type And Thickness

• Reduced Need for PT Girders

• Lateral System Successfully Altered• Building Rotation Reduced• Shear Wall Loads Reduced• Drift And Displacement Reduced

•Project Info


•Project Goals

•Structural Depth

•Architectural Breadth•Construction Breadth


Architectural Breadth

•Project Info


•Project Goals

•Structural Depth



BUILDING ENVELOPE STUDYExisting Curtain Wall• Stick Built • Anchors At Each Level• Aluminum Mullions• Insulating Glass Unit

• ¼” Clear Heat Strengthened Plys• ½” Air Space• Low-E Coating On Surface #2

•Project Info


•Project Goals

•Structural Depth



ORIGINAL FLOOR PLAN REDESIGNED FLOOR PLAN

•Project Info


•Project Goals

•Structural Depth


•Construction Breadth•Comparison and Conclusion

Construction Breadth

rgj5003

Assumptions: Only concrete structure compared 300 Cubic Yards (CY) daily maximum concrete pours 40 hour work week Portions of the sublevel parking garage previously constructed Tendon may not be stressed until 2 days after concrete was poured Remaining construction will stay similar for both designsA new schedule to allow for more post-tensioning equipment and the timing of the contractors and inspectionsConcrete take-offs were performed for both systems, which included concrete, reinforcing and forming

•Project Info


•Project Goals

•Structural Depth



• 94 Days Of Construction

Thesis Building RedesignCurrent Building

• 43 Days Of Construction

rgj5003

Assumptions: Only concrete structure compared 300 Cubic Yards (CY) daily maximum concrete pours 40 hour work week Portions of the sublevel parking garage previously constructed Tendon may not be stressed until 2 days after concrete was poured Remaining construction will stay similar for both designsA new schedule to allow for more post-tensioning equipment and the timing of the contractors and inspectionsConcrete take-offs were performed for both systems, which included concrete, reinforcing and forming

•Project Info


•Project Goals

•Structural Depth



Original Design

Thesis Building Redesign

Comparison

•Project Info


•Project Goals

•Structural Depth




Conclusion:• Uniform Slab Type &Thickness and Column Sizes

• Reduced Floor Weight And Material Use

• Lateral System Modified To Include Moment Frame• Shearwall Loads Reduced

• Floor Plans Were Not Overly Modified

• Sequencing and Cost Increase

•Project Info


•Project Goals

•Structural Depth




QUESTIONSAcknowledgements:

Structura The JBG Companies Cooper Carry

The Pennsylvania State UniversityDr. Linda HanaganProfessor M. Kevin ParfittProfessor Robert HollandProfessor Paul BowersThe entire AE faculty and staff

Special thank you to my parents, my family and my good friends.

800 North Glebe Arlington, VA

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