Urban Construction Challenges
The New York State Society of
Professional Engineers. Inc.
Timothy D. Lynch, PE, Assistant Commissioner
Investigative Engineering Services
Objectives : General
• Protection of the public who live and work in New
York City's large population of 19th Century (17901900) unreinforced masonry structures. In particular:
• The protection of these buildings when the owners
do not maintain them in good order ( existing )
• When the sites are under construction for new
buildings ( new ).
• New and existing buildings competing on lot line.
NYC Building Codes: Code Intent
1625, 1766, 1855, 1899,
1938,1968, 2008, Rules,
TPPNs
1936: C26-3.0 Purpose.
To provide standards, provisions
and requirements for safe and
stable design, methods of
construction and sufficiency of
materials in structures
constructed or demolished…. and
to regulate the maintenance, use
and occupancy of all structures.
Same intent as 1625 code.
Code Themes: Duty, Technical, Site Safety
Duty = law / administrative – generally sunset
Technical provisions – do not sunset
Empirical Designed vs. Engineering Design – do not sunset
Work during construction – sunset
Under Construction – governed by permits – sunset
Under Occupancy – governed by a C of O - technical
Codes: generally material science issue
Structural stability (engineering issues – consistent )
Pre- and Post-permit: Themes
Pre-permit and Post-permit: NB, Alt, DM: code
Certificate of Occupancy: no permit.
Engineering issues – pre-permit
Construction issues – post-permit
Work during construction – generally post-permit
Design – pre-permit. AC and BC.
Under Construction – post-permit Ch 33.
Under Occupancy – C of O – prior codes. Technical
2008 Code: Lawful Use of Existing Buildings
2008 A/C. Lawful Use of Existing Buildings. (duty)
§28-102.4 Existing buildings.
The lawful use or occupancy of any existing building or
structure, including the use of any service equipment
therein, may be continued unless a retroactive change is
specifically required by the provisions of this code or other
applicable laws or rules. The continuation of the unlawful
use or occupancy of a building or structure after the
effective date of this code contrary to the provisions of this
code or other applicable law or rule shall be a violation of
this code.
(Exceptions: Change of occupancy, large alterations, fire
and life safety systems. )
2008 A/C. Lawful Use of New Buildings. (duty)
§28-104.7.1 Submittal of construction documents
NB / Existing Bldgs. Codes
Prior Codes
9
Stakeholder items : Boundary conditions
Source
Existing Buildings
New Building
Date of Construction
Y
N
Plans
Y
Y
Existing Conditions
Y
P
Violation History
Y
N
Construction History
Y
Y
Tax Lot Data
Y
N
Owner Data
Y
P
Historic Data Press
Y
N
Wall Thickness
P
Y
DOB BIS Violations
YP
N
DOB BIS Filings
YP
N
DOB BIS Actions
YP
N
Engineer’s Calculations
P
P
Old Codes
Y
N
Landmarks Data
Y
N
Tax Maps
Y
Y
HPD I cards
Y
N
* Y=Yes, N=No, P=Probable
Unreinforced masonry bldgs
Type of Buildings
Use
Approximate Year
of Construction
Federal Era Buildings
Residential &
Commercial
1789 - 1865
Row Houses
Residential
1840 - 1895
Old & New Law Tenements
Residential
1880-1930
Mercantile Loft Buildings
Commercial &
Industrial
1845-1895
Houses of Worship
Churches /
Community
1790’s - 1900
Identifying the Buildings
Federal Era Buildings
(1789 – 1850’s)
1851 Code: Relieving Wall
Locating the Buildings
Map of New York City 1869
(Source New York Public Library)
Identifying the Buildings
Row Houses
(1840’s – 1900’s)
Engineering Assessment: Schematic
Framing Plans
Code dictated framing around
chimneys and stairs
Code dictated wall
thicknesses
Code dictated full
span joists, and
bearing partitions
Code dictated 3”
Joists and
embedment
lengths
Engineering Assessment: Schematic
Framing Plans
Discontinuity
of Relieving
walls
30% of the joists
brace wall
Identifying the Buildings
Mercantile Loft Buildings
(1850’s – 1890’s)
1886 Code: Required Fire Cuts, 75 PSF Live Load
from one hundred and fifty to five hundred pounds
Look for Data on Site
Identifying the Buildings
Old / New Law Tenement
(1880 – 1920’s)
Codes: Empirical / Prescriptive, Old Law Tenements
Assessment: HPD
Assessment: Key Websites
Open Accessible Space
Information System (OASIS)
NYC DOB - Alterations,
C of O, Actions, Insurance,
Violations
NYC Department of Housing
(HPD) - Floor Plans and
Alteration history
NYPL - digital historical maps
and photos
NYC Automated City Register
Information System (ACRIS) Ownership
Google Maps & Bing
OASIS
• Provides a tax map and aerial view of buildings
• Provides Owner information, estimated building age,
dimensions and height
• Provides links to other important websites
• www.oasisnyc.net . Open OASIS.Enter street address. Open
“Location Report”. Open “NYC DOB” for link to BIS. Open
“Property Transaction Record”. Check for most recent
“DEED”.
• Move cursor to adjacent bldgs. Repeat. This will give BIS
and owner data on adjacent buildings.
Assessment: DOB BIS
• The DOB’s main database
• Property Profile Information
• “Actions”: Pre BIS history. Check for DM / UBs/
EMERG/ IMERG: these are structural issues
• Complaint history
• Insurance information
• www.nyc.gov/buildings
URMs. HPD icards
• I-Cards used prior to 1938 in lieu of C of O’s, often
contain building plans. This runs on “JAVA” – free
download.
• Database of Complaints, Violations and Registration
Information
• History of Alterations
• www.nyc.gov/hpd
Assessment: HPD
Assessment: HPD
Assessment: NYPL
• Historic Tax and Land Maps of New York City
• Maps of wharves and piers / Farm maps / Historical photos
• http://digitalgallery.nypl.org/nypldigital/ Top of home page: Open
“Blogs, Videos and Publications”; left side of next page, open “Digital
Projects”, scroll to page 4/10, open “Early Real Estate Atlases of NY”,
under Early Real Estate…open “Collection Contents”, scroll half way
down to “ Maps of the City of New York 1852, open. Using index maps,
locate street. Back arrow to “Collection Contents” scroll to
Maps.1857,open… continue to 1900.
Assessment: NYPL
1769
1776
Maps of New York
City (Source NYPL)
1857
Assessment: ACRIS
2008 BC Chapter 16 Structural Design – Duty
1604.1 General.
Building, structures and parts thereof shall be designed and constructed
in accordance with strength design, load and resistance factor design,
allowable stress design, empirical design or conventional construction
methods, as permitted by the applicable material chapters.
1604.4 Analysis.
Load effects on structural members. Shall be determined by methods of
structural analysis that takes into account equilibrium, general stability,
geometric compatibility and short and long term material properties. Any
system or method of construction to be used shall be based on a rational
analysis in accordance with well established principles of mechanics.
Such analysis shall result in a system that provides a complete load path
from origin to their load resisting elements.
List of items that result in structural
destabilization
• Benign neglect of existing building.
• Deferred Maintenance
• Historic fires and structural alterations
• Demolition - loss of lateral support to bearing walls
• Excavation – undermining and loss of support at foundations
• Concrete for new buildings poured against existing buildings
Building Analysis Techniques
New Buildings Engineering (Linear)
1.
Technical Training – known (Highly predictive)
2.
Codes – known: national and international (Highly predictive)
3.
Specifications – known (Highly predictive)
4.
Design – known: engineering principals (Highly predictive)
5.
Construction Operations – known: construction codes (Highly
predictive)
6.
Building in Service – Factor of Safety approx 1.6, Highly
predicate. Service life 25 to 50 years.
Building Analysis Techniques
Reverse Engineering (Existing Buildings)
1.
Building in Service – Age from 100 to 200 years, Performance is
highly unpredictable. Factor of Safety 0.9 to 1.XX (usually at unity).
2.
Construction Operations – unknown, questionable construction,
weathering, alterations, trauma, adjacent sites. Highly unpredictable.
3.
Design – unknown, unlikely engineering principals. Highly
unpredictable.
4.
Material Specifications – unknown. Highly unpredictable.
5.
Codes – Mostly focused on fire suppression operations. Mostly
collapse / progressive collapse mechanisms.
6.
Technical Training – 1900’s onwards. Can be discounted.