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Top-Down construction

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by

AHMED ABDELFATTAH

on 15 March 2017

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Transcript of Top-Down construction

?
Bracings
Excavation
Foundations
Columns
Slabs
Marriott Marquis Washington, D.C.
A 15 -story hotel with

7
below-grade levels
Design-Build Contrator
Hensel Phelps Construction Co.
Structural Engineers
Thornton Tomasetti/A+F Engineers
Top-Down Construction

Ahmed Atef Mahmoud
Ahmed Emad Khalifa
Ahmed Mohammed Abdelfattah
Ahmed Mohammed Sayed Ahmed
Ahmed Nazmy Nouh




Presented by :
Prof. Dr. Amr Abdelrahman
Supervisor :
Faculty of Engineering, Ain Shams University, Structural Engineering Department,
4th year Structural Engineering.
Top-Down Construction ?
Harmony
Construction

Deep Excavation

?
Retaining System
1-Sheet Pile Wall
2-RC Pile Wall
3-Diaphragm Wall
a-Strong bearing system.
b-Considered a water tight system.
c-Relatively greater lateral stiffness.
e-No noise and No induced vibrations.
Details
Top-Down Construction

Method (2)
Installation
Precautions
Concreting
Casing Extraction
& Backfilling
Destination Washington
Let's Go For Details

Excavation
Excavator
loader
Procedure
Diaphragm wall
Hydrofraise
Slabs
Slab Opening
Steel Bracket
Steel Shear Studs
Detailing
Coupler
Slab
Diaphragm
U shaped reinforcing bars
Diaphragm wall main steel
Diaphragm
Slab
Haunch
Bend out bars
Diaphragm wall main steel
Connection between Diaphragm Wall &Slab
Advantages of Diaphragm
Temp Supports

Column Installation
Excavating &
Cage Installation
Dust Control
a-Minimizing exposed earth surface.
b-Watering (working & haul areas) during dry period.
c-Using covering haul trucks.
1-Ventilation
2-Access of construction materials & machines
3-Access for removal of excavated soil
Guide walls
Bentonite slurry
Excavating the panel
Installation the reinforcing cage
Filling the pannel with concrete.
Columns
Alternate Studied
Top-Down Construction

Cross lot Bracing
Tie Backs Anchors
Racker Bracing
Special Thanks
Diaphragm Wall
Cristopher Crilly
Senior Project Engineer
Associate at Thornton Tomasetti
“ The use of the so-called top-down construction method on a project that required excavation to a depth of nearly 100 ft helped to resolve a number of site challenges. ”

a) Large soil pressure.
b) Ground water pressure.
c) High lateral stiffness.
d) Permanent load bearing wall.
e) Minimize construction vibration and noise during installation.
Numbers
95 Panels around 450 m
0.9-->1.05 m thickness
37 m Deep
14775 cubic m
1800 Tons of Rebar
Slabs
Expansion Joint

Steel -> 30% Total Slab Area
Steel plates ( 1.5 - 5 cm)
W14 wide flanges

a) Slab openings (sometimes 1/2 area)

d) High lateral earth pressure
c) Construction Joint
d) Floor vibration
e) Resist temporary Force at each stage


structural system
Flat-plate concrete slab (45 -> 60 cm)
Challenges

Partial VS Complete
joint penetration

section might be 25 to 38cm around openings
( require non linear, staged construction analysis)
pour strips used
210 m long structure
concrete Shrinkage occurs in the smaller lengths of the concrete frame
Equipments

Reduce the amount of steel column by 100 ton
W14 Steel Column
Steel can easily spliced together
Numbers
146 Drilled Piers
1.5-2.6 m Diameter
42 m Deep Shafts
1180 tons of Column steel
Construction Load & Structure Self Weight
Composite Section
The full building design loading
Helical Ramp
25 m Diameter
30 m Deep
3 tower cranes
4 dig cranes
Space limitation
Challenges
30 m Deep
92000 sq m excavation area
(span 25 m)
70 X 40 m
Time Challenge
“ This is a top-down project, meaning that work above and below ground will take place simultaneously via a platform built at grade. D.C. and Marriott International Inc. officials are confident the hotel will open as scheduled on May 1, 2014. ”
Civil Engineering Magazine
Washington Business Journal
Ground Water Table
Bucket Of the Muck Hoist
Ground Water Control
Method (1)
Advantages
1-The road traffic is partially disturbed
2-No obstruction during excavation due to bracing
3-No noticeable lateral deformations
Disadvantages
1-High cost
2-More difficult
Used In Tunneling
Grab
Without Columns
Steel Columns
Method (2)
FEB
16
The Flexibility Of Slabs ?
Section of the slab
Openings in the slab
Alf Maskan Station
Line 3 Phase 4
Haroun Station --> Cairo International Airport
15 Km
Method (1)
Full transcript