Section 27-591
§ 27-591 Stability. Except as provided in article twelve of subchapter
eleven of this chapter with regard to foundation elements, a building,
or any element thereof shall be proportioned to provide a minimum factor
of safety of 1.50 against failure by sliding or overturning. The
required stability shall be provided solely by the dead load plus any
permanent anchorages which may be provided.
Section 27-592
§ 27-592 Bracing. Unless otherwise specified in the reference
standards, members used to brace compression members shall be
proportioned to resist an axial load of at least two per cent of the
total compressive design stress in the member braced, plus any
transverse shear therein.
Section 27-593
§ 27-593 Secondary stresses. Secondary stresses in trusses shall be
considered and where of significant magnitude, their effects shall be
provided for in the design.
Section 27-594
§ 27-594 Combination of loads. Dead loads, live loads (including
impact) and reduced live loads, where applicable, shall be considered as
basic loads. Wind, earthquake, thermal forces, shrinkage, and unreduced
live loads (where live load reduction is permitted by subchapter nine of
this chapter) shall be considered as loads of infrequent occurrence.
Members shall have adequate capacity to resist all applicable
combinations of the loads listed in subchapter nine of this chapter, in
accordance with the following:
(a) Where design is based on allowable working stresses, the loads as
described in subchapter nine of this chapter shall be multiplied by the
following factors and the design shall be based on the resulting load
values:
(1) For combinations of basic loads, only, the factor shall be 1.0,
except that for the design of temporary structures (defined as a
structure which will be in place six months or less) the factor shall be
0.75.
(2) For any combination of one or more basic loads with any one load
of infrequent occurrence, the factor shall be 0.75, except that for the
design of temporary structures the factor shall be 0.67.
(3) For any combination of one or more basic loads with two or more
loads of infrequent occurrence, the factor shall be 0.67.
Exception. The provisions of reference standards RS 10-8 and RS 10-9
relating to increases of allowable unit stresses for short-time loading
shall apply.
(b) Where design is based on ultimate strength criteria (including
plastic design of steel structures and proportioning of suspended
structures), the loads, as described in subchapter nine of this chapter
shall be multiplied by the factors indicated in subdivision (e) of
section 27-639 of article eleven of this subchapter and in the
applicable reference standards. The design shall be based on the
resulting load values.
Exceptions. 1. Where combinations of load for which factors are given
in the reference standard include the load of wind (or earthquake) the
design additionally shall consider combinations of load wherein each
other of the loads of frequent occurrence as listed in this paragraph
are substituted for the load of wind.
2. The design also shall consider combinations of load wherein two
most critical of the loads of infrequent occurrence are combined with
the basic loads. For such combination, however, the factors indicated in
the reference standards and in subdivision (e) of section 27-639 of
article eleven of this subchapter for suspended structures, for the
combination of basic loads plus one load of infrequent occurrence may be
reduced fifteen per cent.
Section 27-595
§ 27-595 Deflection limitations. The applicable provisions of the
several reference standards cited in this subchapter shall apply. In
addition, the total of the dead plus live load vertical deflections
(including effects of creep and shrinkage) of members, supporting walls,
veneered walls, or partitions constructed of or containing panels of
masonry, glass, or other frangible materials shall not exceed 1/360 of
the span.
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