All building materials shall be of quality to
meet the intent of the Building Code and shall conform to such specifications
consistent with its requirements as may be promulgated by the Superintendent
of Buildings or, in the absence of such specifications, to well recognized
standards for the materials in question.
A.
Quality of masonry materials.
(1)
Brick. All brick shall be sound, hard, well-burnt
brick. Secondhand brick may be used subject to the approval of the
Superintendent of Buildings as to condition and quality, but in all
cases they shall be thoroughly cleaned before being used and shall
be whole and good, hard, well-burnt brick.
(2)
Concrete hollow tile blocks. Hollow building blocks
of concrete shall be made of portland cement and suitable aggregates
in such proportion as to develop an ultimate crushing strength of
700 pounds per square inch of gross area and tested as laid in the
wall. For partitions, fireproofing and furring, when unexposed to
the weather, solid or hollow concrete budding block or tile having
a minimum ultimate compressive strength of 300 pounds per square inch
of gross area, tested as laid in the wail, may be used, provided that
such units shall be marked on the face with two readily discernible
parallel grooves to indicate that they are units for partition, fireproofing
or furring purposes.
(3)
Terra cotta hollow tile blocks. Structural clay tile
for bearing walls or for walls wholly or partly exposed to the weather
shall at least comply with the standard specifications of the American
Society for Testing Materials, D, C34-34T for medium tile. The minimum
thickness of a single shell or the minimum aggregate thickness of
a double shell shall be one inch. With double shell tiles, the maximum
width of void between shells shall be 5/8 inch. For partitions, fireproofing
or furring, when unexposed to the weather, structural clay tile shall
comply with the standard specifications of the American Society for
Testing Materials, D, C56-34T and shall have exterior shells of not
less than 5/8 inch overall thickness and webs of not less than 1/2
inch overall thickness.
(4)
Gypsum block or tile. Gypsum block or tile shall comply
with the standard specifications of the American Society for Testing
Materials, D, C42-33 and may contain a maximum of 12 1/2% by
weight of combustible matter measured dry.
B.
Mortar and other concrete materials.
(1)
Sand. Sand shall be clean, sharp, coarse and siliceous
and free from salt, lime, clay or other foreign materials.
(2)
Lime. Quick lime and hydrated lime shall conform to
the standard specifications of the American Society for Testing Materials.
(3)
Cement. Portland cements shall conform with the standard
specifications of the American Society for Testing Materials. Nothing
herein contained shall be construed to prohibit the use of cements
of other types which may be approved by the Superintendent of Buildings.
C.
Mortar proportions.
(1)
Cement mortar. Cement mortar shall be composed of
one part of cement and not more than three parts of sand, to which
may be added at most 15% of the cement content in hydrated lime or
lime putty.
(2)
Cement-lime mortar. Cement-lime mortar shall be composed
of one part of cement, one part of lime putty or hydrated lime and
a maximum of six parts of sand.
(3)
Lime mortar, Lime mortar shall be composed of one
part of lime putty or hydrated lime and a maximum of three parts of
sand. Cement may be added to lime mortar replacing equal volumes of
lime, provided that adequate methods of mixing are used so that the
cement gauging will be uniformly distributed.
D.
Quality of materials for reinforced concrete.
(1)
Aggregates. Concrete aggregate shall consist of natural
sands and gravels, crushed rock or other hard durable material that
may be approved by the Superintendent of Buildings. Aggregates shall
be free from strong alkali or organic material.
(2)
Plain concrete proportion. Plain concrete shall be
mixed in the proportions of at least one part of cement to a total
of seven parts of separate volumes of fine and coarse aggregate, measured
dry, and maximum of 8 1/2 United States gallons of water, including
that contained in the aggregate, per sack of cement. Such concrete
shall develop a strength of at least 1,500 pounds per square inch
at the age of 28 days.
(3)
Reinforced concrete proportions. Concrete shall be
mixed in the proportions of at least one part of cement to a total
of 5 1/2 parts of separate volumes of fine and coarse aggregate
measured dry, and a maximum of 7 1/2 United States gallons of
water, including that contained in the aggregate, per sack of cement.
Such concrete shall develop a strength of at least 1,750 pounds per
square inch at the age of 28 days.
(4)
Metal reinforcing. Metal reinforcement shall conform
to the standard specifications of the American Society for Testing
Materials for billet steel concrete reinforcement bars of intermediate
or structure steel, grade D, A15-33, or for rail-steel concrete reinforcement
bars, D, A16-33.
(5)
Structural steel used in reinforced concrete. Structural
steel used in reinforced concrete shall conform to the requirements
of the standard specifications of the Americans Society for Testing
Materials for structural steel for buildings, D, A9-34.
(6)
Wire used in reinforced concrete. Wire for concrete
reinforcement shall conform to the requirements of the standard specifications
of the American Society for Testing Materials for cold-drawn steel
wire for concrete reinforcement, D, A82-34.
(7)
Identification of metal reinforcement. All reinforcing
bars shall be rolled with raised symbols or letters to identify both
the manufacturing mill and the grade of steel. All bundles or rolls
of cold-drawn steel wire reinforcement and on-fourth-inch rounds shall
be securely tagged so as to identify the manufacturer and the grade
of steel.
E.
Iron and steel.
(1)
Cast iron. Cast iron shall be of good foundry mixture
producing a clean, rough, gray iron. It shall conform to the standard
specifications of the American Society for Testing Materials, D, A48-32T,
for medium gray iron castings. Casting shall be free from serious
blowholes, cinder spots and cold shuts.
(2)
Cast steel. Steel castings for building construction
shall be made of open hearth steel and shall be practically free from
blowholes. They shall conform to the standard specifications of the
American Society for Testing Materials, D, A27-24, for medium or soft
steel castings.
(3)
Structural steel. All medium structural steel for
building construction shall conform to the standard specifications
of the American Society for Testing Materials, D, A9-34, as to chemical
and physical properties, inspection, marking and tests. Structural
rivet steel shall comply with the standard specifications of the American
Society for Testing Materials, D, A141-33.
(4)
Use of special steels. Alloy and high carbon steels
may be used in accordance with the rules of the Superintendent of
Buildings as approved by the Board of Trustees.
(5)
Working stresses for special steel. The maximum allowable working stresses in tension for special steels shall be 30% of the minimum ultimate strength, and other stresses may be proportioned to the corresponding allowable stresses for the structural steel specified in § 86-53D, Structural steel.
(6)
Inspection of special steels. All special steel shall
be inspected and accepted by an inspection bureau of known reputation,
acceptable to the Superintendent and, when required, in the presence
of a representative of the Superintendent. An affidavit shall be filed
with the Superintendent by the inspecting bureau to the effect that
the steel, as accepted, is the class of steel required and that it
conforms in all respects to these requirements. Such inspection shall
be at the expense of the owner.
F.
Quality and size of lumber and timber.
(1)
The grades and quality of lumber and timbers used
structurally shall conform to the basic provisions of American lumber
standards as contained in Simplified Practice Recommendations, R 16-29
Lumber, Fourth Edition, Bureau of Standards, United States Department
of Commerce Publications, effective July 1, 1929, except that studding
posts compression members and similar load-bearing members shall be
at least equal to the commercial grade of No. 2 common dimension.
(2)
Beams, girders, joists, rafters, truss members in
tension and flexure, planks and similar load-bearing members less
than five inches in normal thickness shall be of a grade at least
equal to No. 1 common dimension.
(3)
Lumber, five inches thick, and timber shall be at
least equal to the lowest commercial grade for which working stresses
are indicated under tables showing allowable working stresses for
wood beams, girders and similar structural purposes.
(4)
The net size of all lumber and timbers used structurally shall be sufficient to safely sustain their combined live and dead loads within the allowable working stresses fixed by this code. See especially § 86-53F, Lumber and timbers.
(5)
Lumber for load-carrying purposes shall not be used
that is smaller in width and thickness than 1/4 inch scant of the
nominal or commercial description of size, except that American lumber
standard dressed sizes, when seasoned, shall be accepted.
(6)
Computations to determine the required sizes in design
shall be based upon the net cross-sectional area or actual sizes,
and these sizes shall be shown on the plans.
(7)
Wood floor and roof beams, joists, rafters and framing
lumber shall be at least two inches in nominal thickness, except that
no floor or roof beams of structures within the fire limits may be
less than three inches in nominal thickness, and the depths of beams,
joists and girders shall in no case exceed six times such thickness.
(8)
All sheathing of exterior walls on frame buildings,
all subfloors wherever used and all roof boarding shall be not less
than 3/4 inch net thickness and shall be No. 2 common grade or better
and dressed two sides.
A.
When required. New structural material or structural
material not otherwise provided for in this article shall be subjected
to such tests to determine its character and quality as the Superintendent
of Buildings shall direct. Appliances and devices required by any
of the provisions of this chapter and new methods of construction
shall be subjected to such tests to determine their efficiency as
the Superintendent of Buildings may direct. Such tests as may be required
under this section shall be described in rules promulgated by the
Superintendent of Buildings.
B.
Conduct of tests. All tests shall be conducted under
the supervision of the Superintendent of Buildings or his authorized
representative. Laboratory tests shall be conducted at a testing laboratory
of recognized standing. Duly authenticated tests by a competent person
or laboratory may be accepted by the Superintendent of Buildings in
lieu of tests under his supervision. So far as is practicable, test
procedure shall be prescribed in rules duly promulgated by the Superintendent
of Buildings.
C.
Approval. Any material, appliance or method of construction
meeting the requirements of this article or the specifications authorized
thereunder shall be approved within a reasonable time after the completion
of the tests. All such approvals and the conditions under which they
are issued shall be reported and kept on file in the office of the
Superintendent of Buildings and open to public inspection.
D.
Conditions attached to approvals. Materials, appliances
or methods of construction which have been tested and approved shall
be used and installed in accordance with the terms of the approval.
So far as is practicable, all materials and appliances for which approvals
have been issued shall have a distinctive brand mark for identification
impressed on or otherwise attached to them. It shall be unlawful to
use any such brand mark or any other material or appliance than that
for which the approval was issued.
E.
Additional tests. The Superintendent of Buildings
may require tests to be repeated if there is any reason to believe
that a material or appliance no longer conforms to the specifications
on which its approval was based.
F.
Tests on completed work. If there is reason to question
the safety of a structure or part thereof while in the course of construction
or before a certificate of occupancy has been issued, the Superintendent
may require the owner or builder to make load tests or other suitable
tests to determine the acceptability of the construction. Such tests
shall be made under the supervision of the Superintendent of Buildings
and shall show that the construction in question will safely sustain
a load equal to twice the live load prescribed in this article.
G.
Rejection. Any material, appliance or method of construction
failing to conform to the requirements of this code or rules adopted
thereunder shall not be used.
For the purpose of estimating dead loads, in
the absence of more definite information, the weights of building
materials, in pounds per cubic foot, shall be assumed to be as follows:
|
Building Materials
|
Weight
(pounds per cubic foot)
|
|---|---|
|
Brickwork
|
120
|
|
Concrete, stone
|
144
|
|
Concrete, cinder, used for floor arches or slabs
|
108
|
|
Concrete, cinder, used for filling
|
60
|
|
Hollow concrete block masonry
|
108
|
|
Cinder block masonry
|
84
|
|
Gypsum block
|
48
|
|
Hollow tile wall-bearing
|
60
|
|
Hollow tile, partition
|
54
|
|
Plaster, mortar
|
96
|
|
Granite, bluestone and marble
|
170
|
|
Limestone
|
56
|
|
Sandstone
|
144
|
|
Oak
|
50
|
|
Long leaf yellow pine
|
44
|
|
Douglas fir and short leaf yellow pine
|
36
|
|
Spruce, hemlock and white pine
|
30
|
A.
General load requirements. Structures and all parts
thereof shall be of sufficient strength to safely support their imposed
live loads in addition to their own dead load, provided that all structures
shall be designed for at least the minimum live loads specified in
this code, and that the Superintendent of Buildings shall have the
authority to fix live loads for structures not covered by the provisions
of this code.
(1)
Allowance for partition loads. A uniformly distributed
load of 20 pounds per square foot shall be added to the dead loads
of floors in office and public buildings where partitions are not
definitely located in the design, and in other buildings subject to
shifting of partitions, without reference to arrangement of floor
beams or girders. The weight of definitely located partitions shall
be included in the calculation of dead loads.
(2)
Temporary supports. Every temporary support placed
or under any structure or part thereof during the erection, finishing,
alteration or repairing of such structure or part thereof shall be
of sufficient strength to safely carry the load to be supported thereby.
B.
Live loads.
(1)
Live loads to be posted. The live loads for which any and every floor may be designed shall be clearly shown in the application and on the plans before any permit to erect is issued. See also § 86-52, Posting floor capacities.
(2)
Residences and sleeping quarters. For private dwellings,
multiple dwellings, bedroom floors in hotels and clubhouses, private
and ward room floors in hospitals, dormitories and similar occupancies,
including corridors, the minimum live load shall be taken as 40 pounds
per square foot uniformly distributed.
(3)
Office space. For office floors, including corridors,
the minimum live load shall be taken as 50 pounds per square foot
uniformly distributed. Provisions shall be made in designing office
floors for a load of 2,000 pounds placed upon a space of 2 1/2
square feet whenever this load, upon an otherwise unloaded floor,
would produce stresses greater than the 50 pound distributed load.
(4)
Places of assembly other than theaters and hails.
For classrooms with fixed seats, including aisles and passageways
between seats, churches with fixed seats and reading rooms, the minimum
live load shall be taken as 60 pounds per square foot uniformly distributed.
(5)
Theaters and assembly hails. For the seating space in theaters and assembly hails with fixed seats, including the passageway between seats, except as provided in Subsection B(6) below, the minimum live load shall be taken as 75 pounds per square foot uniformly distributed.
(6)
Public spaces. For aisles, corridors not otherwise provided for above, hails, lobbies, public space in hotels and public structures assembly halls without fixed seats, theater stages, cabarets, barrooms, art galleries and museums, stores, restaurants, skating rinks, grandstands, gymnasiums, dance halls, dining rooms, lodge rooms, laboratories in school and college buildings, stairways, fire escapes and exit passageways and other spaces where groups of people are likely to assemble, the minimum live load shall be taken as 100 pounds per square foot uniformly distributed. This requirement shall not apply to such spaces in private dwellings for which the minimum live load shall be taken as in Subsection B(5) above.
(7)
Industrial or commercial occupancies. In designing
floors for industrial or commercial purposes other than previously
mentioned, the live load shall be assumed as the maximum caused by
the use which the structure or part of the structure is to serve.
The following loads, in pounds per square foot uniformly distributed,
shall be taken as the minimum live loads permissible for the occupancies
listed, and loads at least equal shall be assumed for uses similar
in nature to those listed in this section. Floors to be used for:
(a)
The display and sale of light merchandise and
where incidental factory work does not utilize more than 25% of the
floor area: 75 pounds per square foot.
(b)
Factory work, wholesale stores, storage and
stock rooms in libraries: 120 pounds per square foot.
(c)
Stables: 75 pounds per square foot.
(d)
Garages for passenger cars only: 75 pounds per
square foot. When there is floor area sufficient for the accommodation
of two or more cars, the design of floors for such garages shall make
provision for a concentrated load of 2,000 pounds at any one point.
(e)
(f)
Trucking spaces and driveways within the limits
of a structure: 175 pounds per square foot. The design of floors for
such trucking spaces shall also make provision for the heaviest concentrated
loads to which they may be subjected, but in all cases these loads
shall be assumed as at least 24,000 pounds concentrated at any point
on a beam or girder.
(8)
Moving loads. For structures carrying live loads which
cause shock and vibration, a proper percentage shall be added to the
live-load stress to provide for dynamic effects.
(9)
Roof loads.
(a)
Roofs having a rise of four inches or less per
foot of horizontal projection shall be designed to safely carry a
vertical live load of not less than 40 pounds per square foot of horizontal
projection to any or all slopes.
(b)
Roofs having a rise of more than four inches
and not more than 12 inches per foot of horizontal projection shall
be designed to safely carry a vertical live load of not less than
30 pounds per square foot of horizontal projection.
(c)
Roofs having a rise of more than 12 inches per
foot of horizontal projection shall be designed to safely carry a
wind force, acting normal to the roof surface, on one slope at a time,
of 30 pounds per square foot of such surface.
(10)
Sidewalk loads. For public sidewalk area between the
curb and building lines, the live load shall be taken at 300 pounds
per square foot.
(11)
Yard and court loads. For yards and courts inside
the building line, the live loads shall be taken at not less than
150 pounds per square foot.
(12)
Reduction of live loads.
(a)
In structures intended for storage purposes,
all columns, piers or walls and foundations may be designed for 85%
of the full assumed live load. In buildings intended for other uses,
the assumed live load used in designing all columns, piers or walls
and foundations may be as follows:
[1]
One hundred percent of the live load on the
roof.
[2]
Eighty-five percent of the live load on the
top floor.
[3]
Eighty percent of the live load on the next
floor below.
[4]
Seventy-five percent of the live load on the
next floor below, and on each successive lower floor, corresponding
decreasing percentages, provided that in all cases at least 50% of
the live load shall be assumed.
(b)
Girders, except in roofs and as specified in Subsection B(12)(c) below, carrying a designed floor load, the equivalent of 200 square feet or more of floor area, may be designed for 85% of the specified live loads.
(c)
In designing trusses and girders which support
columns and for determining the area of footings, the full dead loads,
plus the live loads shall be taken with reduction figured as permitted
above.
(13)
Safes restricted. No safe shall be placed on a stair
landing or in a stair hall nor shall its weight be carried by any
beam which also carries the floor of any landing or stair hall.
A.
General requirements for wind pressure. All structures
shall be designed to resist a horizontal wind pressure on all surfaces
exposed to the wind, allowing for wind in any direction, of not less
than 15 pounds per square foot for those portions less than 40 feet
above the ground and of not less than 30 pounds per square foot for
those portions more than 40 feet above ground, provided that the wind
pressure on signs, tanks, towers and stacks shall be assumed as 30
pounds per square foot for any height.
B.
Stability. The overturning moment due to wind pressure
shall not exceed 80% of the moment of stability of the structure,
unless the structure is securely anchored to the foundation.
C.
Allowable stresses.
(1)
For combined stresses due to wind and other loads,
the working stresses prescribed in this article may be increased 33 1/3%,
provided that the section thus found is not less than that required
by the dead load and live loads alone.
(2)
For members carrying wind stresses only, the permissible
working stresses may be increased 33 1/3%.
A.
New and altered buildings. The live load for which
each floor or part of a floor of a business building or storage building
hereafter erected or altered is designed and approved by the Superintendent
of Buildings shall be conspicuously posted in that part of the story
to which it applies.
B.
Existing buildings.
(1)
In every business building or storage building now
existing in which heavy materials are kept or stored or machinery
is introduced, the live load that each floor will safely sustain shall
be estimated by the owner or occupant or by a competent person employed
by the owner or occupant. Such estimate shall be filed with the Superintendent
of Buildings and, if found satisfactory and approved by him, shall
be posted as provided for new buildings.
(2)
If the Superintendent of Buildings shall have cause
to doubt the correctness of said estimate, he is empowered to revise
and correct the same and, for the purpose of such revision, the officers
and employees of the Department of Buildings may enter any building
and remove so much of any floor or other portion of the structure
as may be required to make necessary measurements and examination.
Any expense necessarily incurred in removing any floor or other portion
of a structure for the purpose of making the examination herein provided
for shall be paid by the Treasurer upon the requisition of the Board
of Trustees. Such expense shall be a charge against the person or
persons by whom or on whose behalf said estimate was made, provided
that such examination proves the floor or other portion of the structure
of insufficient strength to safely sustain the estimated live load.
C.
Loading restricted. No person shall place or cause
or permit to be placed on any floor of a building or on any part of
a structure a greater load than the approved safe load.
A.
General requirements.
(1)
Computations. Every structure hereafter erected and
all new construction in the alteration of an existing structure shall
be so designed and constructed that the working stresses fixed in
this section are not exceeded. In using these stresses, the effects
of all loads and conditions of loading and the influence of all forces
affecting the design and strength of the several parts shall be taken
into account.
(2)
Permissible working stresses. Higher stresses than
herein specified may be used, but only if it is clearly established
by test or other satisfactory evidence that material of a higher grade
or a superior workmanship than the accepted standard is to be employed.
The use of higher stresses, however, shall not be allowed until a
statement giving the reasons for such permission, together with the
facts and circumstances on which it is based, is placed on file and
made a part of the official record of the permit.
(3)
Working stresses not specified. For materials permitted
in the construction of structures which are not provided for in this
section, the Superintendent of Buildings shall, by rule, establish
working stresses.
B.
Stone and masonry.
(1)
Natural stone masonry.
(a)
The maximum allowable compressive stresses for
masonry of natural stone with dressed or cut beds, due to combined
live and dead loads, expressed in pounds per square inch of gross
cross-sectional area are given in the following table:
|
Kind
|
Mortar Cement
(pounds per square inch)
|
Cement-Lime Mortar
(pounds per square inch)
|
Lime Mortar
(pounds per square inch)
|
|---|---|---|---|
|
Granite
|
800
|
640
|
400
|
|
Gneiss
|
750
|
600
|
375
|
|
Limestone
|
500
|
400
|
250
|
|
Marble
|
500
|
400
|
250
|
|
Bluestone
|
400
|
300
|
175
|
|
Sandstone
|
300
|
250
|
150
|
(b)
The maximum allowable compressive stress for
other natural cut stone masonry and for all uncut stone masonry shall
be 140 pounds per square inch of gross cross-sectional area in cement
mortar and 110 pounds in cement-lime mortar.
(2)
Masonry. The working stresses, in pounds per square
inch, in masonry in compression shall be taken as follows:
|
When Laid in
|
Portland Cement Mortar
(pounds per square inch)
|
Cement-Lime Mortar (pounds
per square inch)
|
Lime Mortar (pounds per square
inch)
| |
|---|---|---|---|---|
|
Brickwork
|
250
|
150
|
100
| |
|
Hollow building blocks
| ||||
|
Gross area:
| ||||
|
Concrete cells vertical,
|
80
|
70
| ||
|
Concrete cells horizontal,
|
30
|
25
| ||
|
Terra cotta cells vertical,
|
120
|
100
| ||
|
Terra cotta cells horizontal
|
70
|
60
| ||
|
Plain concrete masonry (1 to 7 mix)
|
400 pounds per square inch
| |
|
Grout, neat portland cement in thin layers under
bases only
|
1,000 pounds per square inch
| |
|
Grout, (1 1/2 mix)
|
600 pounds per square inch
|
C.
Reinforced concrete.
(1)
Concrete. The allowable working stresses, in pounds per square inch, and the ratio (n) for concrete mixed in the proportions as specified in § 86-47D(3), 1:5 1/1 mix, shall be taken as follows:
|
Flexure: FC
| ||
|---|---|---|
|
Designation
|
Description
|
Allowable Working Stresses
(pounds per square inch)
|
|
S1
|
Extreme fiber stress in bending
|
650
|
|
S2
|
Extreme fiber stress in compression adjacent
to supports
|
750
|
|
Shear: V
| ||
|
S3
|
Beams without web reinforcement and without
special anchorage of longitudinal steel
|
40
|
|
S4
|
Beams without web reinforcement but with special
anchorage of longitudinal steel
|
60
|
|
S5
|
Beams with properly designed web reinforcement
but without special anchorage of longitudinal steel
|
100
|
|
S6
|
Beams with properly designed web reinforcement
and with special anchorage of longitudinal steel
|
150
|
|
S7
|
Flat slabs at distance (d) from edge of column
capital or drop panel
|
60
|
|
S8
|
Footings where longitudinal bars are without
special anchorage
|
40
|
|
S9
|
Footings where longitudinal bars have special
anchorage
|
60
|
|
Bond: U
| ||
|
In beams, slabs and one-way footings:
| ||
|
S10
|
Plain bars
|
80
|
|
S11
|
Deformed bars
|
100
|
|
In two-way footings:
| ||
|
S12
|
Plain bars
|
60
|
|
S13
|
Deformed bars
|
75
|
|
Bearing: FC
| ||
|
S14
|
Direct
|
500
|
|
Axial compression: FC
| ||
|
S15
|
In columns
|
500
|
|
S16
|
In pedestals
|
500
|
|
S17
|
Ratio (n)
|
15
|
(2)
Steel reinforcement. The maximum allowable working
stresses, in pounds per square inch, for reinforcing steel shall be
as follows:
|
Description
|
Allowable Working Stress
(pounds per square inch)
| |
|---|---|---|
|
Rail steel bars in tension
|
fs 16,000
| |
|
Structural steel grade billet steel in tension
|
fs 18,000
| |
|
Cold-drawn steel wire in tension
|
fs 20,000
| |
|
Web reinforcement
|
fv 16,000
| |
|
Steel bars in compression
|
nfc
|
(3)
Controlled concrete. When concrete is used of a mixture,
the strength of which at the age of 28 days shall be 2,200 pounds
per square inch or more, the product shall be known as controlled
concrete." The allowable working stresses shall be based on the ultimate
compressive strength of the concrete (fc), as determined by test,
and for which the proportions of water to cement ratios shall be fixed
by the Superintendent of Buildings. All field tests of concrete, tests
of materials, load tests and other tests deemed necessary by the Superintendent
of Buildings shall be made without expense to the Village. The maximum
allowable working stresses, in pounds per square inch, shall be as
follows:
|
Flexure: FC
| ||
|---|---|---|
|
Designation
|
Description
|
Allowable Working Stresses (f'c)
|
|
S1
|
Extreme fiber stress in compression
|
0.40
|
|
S2
|
Extreme fiber stress in compression adjacent
to supports of continuous or fixed beams or slabs or of rigid frames
|
0.45
|
|
Shear: V
| ||
|
S3
|
Beams without web reinforcement and without
special anchorage of longitudinal steel
|
0.02
|
|
S4
|
Beams without web reinforcement but with special
anchorage of longitudinal steel
|
0.03
|
|
S5
|
Beams with properly designed web reinforcement
but without special anchorage of longitudinal steel
|
0.06
|
|
S6
|
Beams with properly designed web reinforcement
with special anchorage of longitudinal steel
|
0.09
|
|
S7
|
Flat slabs at distance (d) from edge of column
capital or drop panel
|
0.03
|
|
S8
|
Footings where longitudinal bars are without
special anchorage
|
0.02
|
|
S9
|
Footings where longitudinal bars have special
anchorage
|
0.03
|
|
Bond: U
| ||
|
In beams, slabs and one-way footings:
| ||
|
S10
|
Plain bars
|
0.04
|
|
S11
|
Deformed bars
|
0.05
|
|
In two-way footings:
| ||
|
S12
|
Plain bars
|
0.03
|
|
S13
|
Deformed bars
|
0.0375
|
|
Where special anchorage is provided, § 86-61I, double these values in bond may be used.
| ||
|
Bearings: FC
| ||
|
S14
|
Direct bearing
|
0.30
|
|
Axial compression: FC
| ||
|
S15
|
In columns
|
0.25
|
|
S16
|
In pedestals
|
0.30
|
|
S17
|
Ratio (n)
|
30,000
|
D.
Structural steel, All parts of structures shall be
so proportioned that the sum of the maximum static stresses, in pounds
per square inch, shall be within the following:
(1)
Tension stresses. Rolled steel on net section: 18,000
pounds per square inch.
(2)
Compression stresses.
(a)
Rolled steel on short lengths or where lateral
deflection is prevented: 18,000 pounds per square inch.
(b)
On gross section of columns:
(b).tif.png) | |
|
with a maximum of 15,000 pounds per square inch
in which "L" is the unsupported length of the column and "r" is the
corresponding least radius of gyration of the section, both in inches.
|
(c)
For main compression members, the ratio L to
r shall be within 120, and for bracing and other secondary members,
the ratio shall be 200.
(3)
Bending stresses.
(a)
On extreme fibers of rolled shapes and built-up
sections, net section if lateral deflection is prevented: 18,000 pounds
per square inch.
(b)
When the unsupported length, "L," exceeds 15
times "b," the width of the compression flange, the stress, in pounds
per square inch, in the latter shall be within:
(b).tif.png) | |
|
The laterally unsupported length of beams and
girders shall be within forty times "b," the width of the compression
flange.
|
(c)
On extreme fibers of pins, when the forces are
assumed as acting at the center of gravity on the pieces: 27,000 pounds
per square inch.
(4)
Shearing stresses.
|
On
|
Pounds Per Square Inch
| |
|---|---|---|
|
Pins
|
13,500
| |
|
Power-driven rivets
|
13,500
| |
|
Hand-driven rivets
|
10,000
| |
|
Unfinished bolts
|
10,000
| |
|
Gross area of the webs of beams and girders
|
12,000
|
(5)
Bearing stresses.
|
On
|
Double Shear
(pounds per square inch)
|
Single Shear
(pounds per square inch)
| |
|---|---|---|---|
|
Pins
|
30,000
|
24,000
| |
|
Power-driven rivets
|
30,000
|
24,000
| |
|
Hand-driven rivets
|
20,000
|
16,000
| |
|
Unfinished bolts
|
20,000
|
16,000
|
E.
Cast iron.
(1)
All structural members of cast iron shall be so proportioned
that the sum of the maximum static stresses, in pounds per square
inch, shall be within the following:
|
Stress
|
Pounds Per Square Inch
| ||
|---|---|---|---|
|
Tension
|
3,000
| ||
|
Shear
|
3,000
| ||
|
Bending:
| |||
|
Extreme fiber-compression side
|
16,000
| ||
|
Extreme fiber-tension side
|
3,000
| ||
(2)
Compression on columns: 9,000 pounds per square inch
minus 40 .tif.SM.png)
. In no case shall the ratio of L to r exceed 70
where "L" is the length in inches and "r" is the least radius of gyration.
.tif.png)
. In no case shall the ratio of L to r exceed 70
where "L" is the length in inches and "r" is the least radius of gyration.F.
Lumber and timbers.
(1)
The net size of all lumber and timbers used structurally
shall be sufficient to safely sustain their imposed loads within the
allowable working stress fixed by this section.
(2)
Stresses due to live and dead loads, acting singly
or combined, shall be within those fixed in Tables I and II.
(3)
Stresses due to wind load, singly or combined with
live and dead loads, may be increased 30% of these allowable working
stresses when the resulting section equals or exceeds that required
for design of total live and dead load.
(4)
All lumber and timber used as structural members of
any structure shall bear the official grademark and trademark of the
association under whose grade rules it was manufactured. Except for
frame dwellings and accessory buildings, the Superintendent of Buildings
may permit the use of lumber or timber not bearing an official grademark
and trademark, provided that said lumber or timber is approved by
the Superintendent as to quality and condition, and provided further
that the allowable working stresses shall not exceed 66 2/3%
of the allowable stresses shown in Tables I and II.[1]
[1]
Editor's Note: Tables I and II are included as attachments
to this chapter.
A.
Presumptive capacities.
(1)
In the absence of satisfactory tests, the sustaining
power per square foot, of different soils shall be deemed to be as
follows:
|
Soil
|
Sustaining Power
(tons per square foot)
| |
|---|---|---|
|
Quicksand
|
0.5
| |
|
Softclay
|
1
| |
|
Wet sand (confined)
|
2
| |
|
Firm clay
|
2
| |
|
Sand and clay, mixed or in layers
|
2
| |
|
Fine dry sand
|
3
| |
|
Coarse sand
|
4
| |
|
Gravel
|
6
| |
|
Softrock
|
8
| |
|
Hardpan (overlaying rock)
|
10
| |
|
Medium rock
|
25
| |
|
Hard rock
|
40
|
(2)
In case a structure rests partly on rock or hardpan
and partly on some other soil, the bearing capacity of the latter
shall be taken at not more than 1/2 of the capacity otherwise assumed.
B.
Soil tests. When a doubt arises as to the safe sustaining
power of the soil upon which a structure is to be erected or it is
desired to exceed the presumptive capacity, the Superintendent of
Buildings may direct that borings or tests be made by and at the expense
of the owner of the proposed structure to determine the sustaining
power of the soil. Whenever such a test is made, the Superintendent
of Buildings shall be notified so that he may be present in person
or by a representative. A complete record of the test shall be filed
with the Superintendent of Buildings.
C.
Filled ground. No foundation of a structure shall
be placed on filled ground until proper tests to determine the safe
sustaining power of such filled ground have been made to the satisfaction
of the Superintendent of Buildings.
D.
Indicative statement required. Applications for permits
for new buildings and, when necessary, for alterations to existing
buildings shall contain a statement of the character of the soil at
the level of the footings.
