Structural Option Advisor: Walter Schneider / Ali Memari The Pennsylvania State University 110 Third Avenue New York, NY 10003 Spring 2006 Design and Analysis

Structural OptionAdvisor: Walter Schneider / Ali Memari

The Pennsylvania State University110 Third Avenue

New York, NY 10003Spring 2006

Design and Analysis of 110 Third Avenue

Anthony Nicastro

Overview

•Building DescriptionBuilding Description

•Existing Structural SystemExisting Structural System

•Problem Statement and Proposed SolutionsProblem Statement and Proposed Solutions

•Design Work:Design Work:

•Floor Layout/Column DesignFloor Layout/Column Design

•Floor SlabFloor Slab

•Lateral SystemLateral System

•Breadth WorkBreadth Work

•Building Envelope DesignBuilding Envelope Design

•Cost and Constructability of PT slabsCost and Constructability of PT slabs

Building Description

Project TeamProject TeamOWNER: TOLL BROTHERS INC.

ARCHITECT: GREENBERG FARROW

STRUCTURAL ENGINEER: AXIS DESIGN GROUP

MEP ENGINEER: MGJ ASSOCIATES INC.

GEOTECHNICAL ENGINEER: LUNGAN

CM AGENT: TISHMAN CONSTRUCTION

CONSULTANT: LZA/THORTON-TOMASETTI

ArchitectureArchitecture•Net Square Feet: 107,100 SF•Usage:

Primary Occupancy- ResidentialSecondary Occupancy- Retail,

Floor 1•Number of Stories: 21 above grade, 2 below

•The exterior walls of 110 Third Ave. consist of a “window wall” system. This system is fixed window units fabricated with flush aluminum panels finished to match the window wall that rests on the slab.

•On the North and East sides of the building are balconies from floors 8 through 16 and 16 through 21, respectively.

•Setback at floor 16



ElectricalElectrical•Electrical service is brought into 110 Third Avenue by Con-Edison service 120/208V 3 Phase 4 wire distributed to two switchboards located on the cellar level.

•Switchboard 1 services the residential portions of the building, retail space, and gym area Switchboard 2 powers utilities such as the sprinkler system, fire pumps and elevators.

•Circuit wire sizes are most commonly 2 #12-3/4”C, and branch circuit breakers are most commonly 1 pole, 20 Amp.

LightingLighting•Kitchen Fixtures:

Recessed ceiling downlighting.Continuous undercabinet task lighting.Pendant task lighting above island countertops.

•Bathrooms: Recessed ceiling downlighting.Mirror task lighting.

•Walk-in Closets:Utility wall Sconce.

•Apartment Halls:Recessed ceiling downlighting.

•Common Residential Corridors And Elevator Lobbies:Recessed ceiling downlighting



Mechanical SystemMechanical System•2400#/hr and 2,400,000 BTU/hr. steam supply

•Heat exchanger supplies individual units via individual hot water unit heaters.

•A second heat exchanger serves the primary condenser water loop and is tied to a 2-cell cooling tower serving the water-source heat pumps at 990 CPM per tower with 330 tons capacity per tower.

•CFM total is 48680

•Common spaces are conditioned by a dedicated VAV box rated at 1040 CFM.

Structural SystemStructural System•CIP concrete system•8” two-way slab system•Loads are carried from the two-way slab system to concrete columns ranging from 12x12 to 40x12•Concrete columns recessed from perimeter approximately 10” to allow for non-bearing exterior panels•The only beams present in the structure surround the elevator core and stairwell, and also grade beams in the basement level that extend to the face of the building. •Roof is flat slab system with roof drains nested under pavers•Footings range from 4’6” square up to 15’ x 9’6”•Shear walls extend entire height of the building and are located around the elevator core.


Structural System

Floor system:Floor system:

•68’ x 75’

•Typical bay size is 12’ to 15’ square

•Loading:

•25 psf DL, 40 psf LL in apts.

•100 psf LL in stairs

•5000 psi Concrete slab, 8” thick typ.

Structural System

Vertical Elements and Vertical Elements and Considerations:Considerations:

•Height restriction of 210’

•21 Stories each approximately 9’-8” except for lower floors and penthouse

•5000 psi concrete columns

Structural System

Lateral SystemLateral System

•Two-part system

•Shear walls surrounding the elevator core

•Columns and floor slab cast monolithically form a moment frame

Structural System

Structural System

North Elevation

Structural System

West Elevation

Problem Statement and Proposed Solutions

• Create a design that meets the height restriction while including the most floors possible with the most space possible.

• Floor system must remain 8” thick or thinner

• Maintain strength of system without compromising span length

• Ease of construction/installation

Problem Statement and Proposed Solutions

Depth WorkDepth Work• Column design• Floor system design• Lateral force resisting system design

– Shear wall only– Combined system

Breadth WorkBreadth Work• Building Envelope Design• Cost and Constructability of PT slabs

Column Design

• Design floor layout to support larger bays with fewer columns

• Initial Design:– Leaning columns, moments from uneven floor

loading only– PCA COL aided in design of reinforcement– Hand check of column to insure PCA COL

accurate design

Column Design

• Final Design– Columns take moment from lateral forces– Forces on columns taken from ETabs and

reapplied in PCA COL– All columns remained the same size except for

columns 7 and 8 which increased by an inch in one direction

• ETabs showed no change in cross sectional area• PCA COL showed an increase of 1 inch was necessary

Column Design

Column Design

Column Design

Column DesignArchitectural Impact of New Column Layout

• Design post-tensioned slab using RAM Concept as an aid

• Keep slab 8” thick• Banded tendons at column lines

Floor Slab

Floor Slab

Latitude Tendons

Floor Slab

Longitude Tendons

Floor Slab

Floor Slab

Floor Slab

Lateral Force Resisting System

• Examine a new lateral system: Shear walls only


• Design the old lateral force resisting system, a combination system, to adapt to the new floor layout






Building Envelope Design

• The window-wall system could have several water penetration issues develop over the course of the building’s life

• Barrier system that should repel water and not allow any penetration whatsoever.

• Wall sections provided by the architect do not show some critical transition points between materials.



• In the case of 110 Third Avenue, the wall system provides no way for the glazing pocket to drain

• Operable windows need a way to drain, so there should be some way for them to drain along the sill track.

• The sill track should have weep holes that can give the water a way to escape the system without the tendency to penetrate through to the inside.




•Gaskets should have fully vulcanized corners—tend to shrink over time

•Clear sealer applied to exposed concrete

•Double sealant joint at the head and the jamb

•Installation of a swing stage



•Addition of a waterstop and waterstop slurry where floor slab meets parapet

•Addition of a protection board underneath the drainage panels—supplement the system

•Flashing at the ends of the parapet should continue all the way down past the pedestal

Cost and Constructability of PT Slabs

• Cost of original, regularly reinforced floor slab per floor:

$36,994$36,994

• Cost of new, post-tensioned slab per floor:

$40,090$40,090


• Offsetting costs – Less construction time: Fewer columns– Less formwork


• Constructability– PT contractors not readily available in

the NY metropolitan area– Contractors from New Jersey

Summary and Conclusions

• PT floor slab not conducive to the New York construction market because of availability issues

• Anywhere else, i.e., Washington DC, they are comparable designs

• The new design for 110 Third Avenue functions well within the bounds of code requirements and can be considered a valid design for the future.

Comments/Comments/QuestionsQuestions

Documents

Structural Option Advisor: Walter Schneider / Ali Memari The Pennsylvania State University 110 Third Avenue New York, NY 10003 Spring 2006 Design and Analysis