1. 108 Delancey Street
Lower Eastside Manhattan
April 4, 1984
By: David M. Ulrich and Keith Malmberg
Drawings by David M. Ulrich in AutoCAD 2010
Purpose : To retrofit a concrete masonry unit (CMU) and
wood floor construction building with structural steel and
concrete slab on metal decking
DM
A
Consultants and Construction Managers

2. 1st Floor
2nd Floor
3rd Floor
4th Floor
5th Floor
Cross section of existing building
• Five floors of wood
flooring (beams/joists)
Building 1 Building 2
• Two buildings share central
load-bearing wall
• Building 1 and Building 2
interiors are completely
separate
• Current system utilizes
continuous CMU stem wall
footings

3. 1st Floor
2nd Floor
3rd Floor
4th Floor
5th Floor
Proposed Retrofit Agenda
• Remove 2nd Floor and
Central CMU bearing wall
Building 1 Building 2
• Replace 1st floor with
structural steel and slab-on-
metal decking
• Retrofit continuous stem
wall footings into three main
spread footings
• Utilize wide-flange columns,
beams, and girders in lieu of
structural masonry

4. • Removal of 2nd floor
resulting in large space with
vaulted ceiling
Cross section of proposed retrofit
2nd Floor
• Installation of three spread
footings into existing bearing
wall (Epoxy Installation)
• Support the multi-wythe
CMU bearing wall from 3rd
Floor to Roof

5. Base Plate with
(4) 3/4" Threaded rods
W10x49 ColumnW12x26 Beam
3 1/2" conc. slab
on 22ga. metal deck
W12x50 Girder
Steel retrofit design
Here are some basic
components of the
proposed retrofit design
W 12 x 50
What Does This Mean?
12” Flange-to-Flange dimension
50 lbs per linear foot
W Shape

6. 13" UNO 10" min embed
Footing to steel column connection
Concrete Slab-on-Grade
Wide Flange column
Spread Footing
Non-shrink grout
Base Plate + Threaded Rods

7. Footing Installation
Subgrade assessment
Form Installation
Undisturbed Native Soils?
No
Firm and Unyielding Soils?
Use a flat bucket for excavation
Replace soils removed
Footing Dimensions
Location
No
Over excavate to dense soils
Adequate form bracing to
support lateral load of concrete
Ensure column will load footing
as designed
1
2

8. Spread Footing Concrete Placement
1
2
3
Secure rebar prior to concrete
placement (3” from earth per ACI)
Place anchor bolts correctly in
relation to the rebar mat per
plans
Mechanically consolidate concrete
with a vibrator
4 Leave adequate clearance below
base plate template for non-shrink
grout
3 Inches

9. Footing ‘spreads’ load from the
footing bottom to earth beneath
Notice the column assembly
In the center of the footing
Correct Spread Footing Load Path

10. Spread Footing Loading
OK NOT OK NOT OK NOT OK
1 2 3 4
GOOD
BAD
Eccentric LoadingStandard Central Loading

11. To Remove Floor #1 and #2 we will
need Shoring.
• Floors need to be shored
prior to removal of load-
bearing wall sections
• Shoring can be rented until
concrete has reached full
strength and is adequate for
support
• Falsework of this magnitude is
not to be ‘site-designed’ by a
contractor.
• Consult with an engineer
for shoring design
Adjustable screw with baseplate

12. 108 Delancey Street

13. 12" CMU Block Wall
8" CMU Block Wall
Spread Footings
104 Delancey St 106 Delancey St
5StoriesAbove
Concrete stem wall foundation
and Concrete Masonry Unit
walls (CMU blocks)
Three critical spread footings
along shared central wall
Multi-wythe CMU walls of
different block width
1
2
3
Floor Plan
A
B
C

14. A vague list of what went wrong
• Lack of field supervision and inspection oversight
• Lack of step-by-step construction sequence resulting in lateral
instability
• No shop drawings
• Spread footings were installed incorrectly
• Spread footings were installed below 50% of design strength
• Spread footings were eccentrically loaded
• Shoring schedule out of sequence
• Removal of 3rd floor and pouring one side created a twisting force
• Lack of lateral support coupled with eccentrically loaded
footings created an inevitable collapse

15. What went wrong with the footings?
• Footing dimensions were installed wrong (contractor at fault)
• Footing were eccentrically loaded (contractor at fault)
Actual footing installation
A
B C
• Some of the footings were less than 40% design size
Did the contractor have structural plans?
Footing dimensions
AS DESIGNED BY ENGINEER
Footing Length Width Ft2
% Design
A 8'6 5'6 47 ft2
44%
A 4'8 4'7 21 ft2
B 5'6 7'0 39 ft2
51%
B 5'9 3'6 20 ft2
C 5'6 7'0 39 ft2
36%
C 4'2 3'4 14 ft2
Designed Footing Dimensions
Installed Footing Dimensions
44%
51% 36%

16. What went wrong with the shoring?
1. The contractor removed both sides the 3rd floor
2. The contractor only poured back one side of floor 3
3. Floor 3 had no lateral stability when it began to twist

18. THE END