CHAPTER 16

1 2014 NEW YORK CITY BUILDING CODE353 CHAPTER 16 structural DESIGNSECTION BC Scope. The provisions of this CHAPTER shall govern thestructural design of buildings, structures and portions thereofregulated by this code. (Note: Where the text in this Coderefers to ASCE 7, the 2005 edition shall be used; and wherethe text in this Code refers to ASCE 7-10, the 2010 editionshall be used.) Special provisions for prior code buildings. Theprovisions of Sections through shall applyto structural work on prior code Use of this code. Notwithstanding the appli-cant s election to use the 1968 Building Code or priorcode, the structural calculations shall be permitted to beperformed in accordance with this code provided that thestructural safety of the prior code building is not the provisions of Section ofthe Administrative Code, the use of load and ResistanceFactor Design (LRFD) engineering calculations shall notbe deemed to reduce structural safety provided the proper-ties of the existing materials are determined usingaccepted engineering Live loads.

2 Loads indicated in the applicableprior code shall be permitted for structural calculationsusing engineering formulas from this code provided thatthe structural safety of the prior code building is Seismic loads. The determination as to whetherseismic requirements apply to an alteration shall be madein accordance with the 1968 Building Code and interpreta-tions by the department relating to such applicable seismic loads and requirements, includingfor the bracing of architectural, mechanical, plumbing,fuel gas, fire suppression and electrical systems and equip-ment, shall be permitted to be determined in accordancewith this CHAPTER or the 1968 Building Code and referencestandard RS 9-6 of such Wind loads. All alterations, minor alterations,and ordinary repairs, to the extent of such work, shall bepermitted to be performed in accordance with the windload requirements set forth in the 1968 Building Code, orwhere the 1968 Building Code so authorizes, the code ineffect prior to December 6, :1.

3 Equipment, appliances and supports that areexposed to wind shall be designed and installedto resist the wind pressures determined in accor-dance with Section Wind loads on glass shall not be permitted to becalculated in accordance with the code in effectprior to December 6, When the wind surface area of a prior code build-ing or structure is increased by more than 5 per-cent in any direction or there is a permanentdecrease of the lateral force capacity by morethan 20 percent in any direction, the entire build-ing or structure shall be designed to resist thedesign wind load as calculated pursuant to theapplicable code, but not less than 5 psf ( kN/m2).SECTION BC 1602 DEFINITIONS AND Definitions. The following words and terms shall, forthe purposes of this code, have the meanings shown STRESS DESIGN.

4 A method of propor-tioning structural members, such that elastically computedstresses produced in the members by nominal loads do notexceed specified allowable stresses (also called workingstress design ).BALCONY, EXTERIOR. See ASCE LOADS. The weight of materials of constructionincorporated into the building, including but not limited towalls, floors, roofs, ceilings, stairways, built-in partitions,finishes, cladding and other similarly incorporated architec-tural and structural items, and the weight of fixed serviceequipment, such as cranes, plumbing stacks and risers, elec-trical feeders, heating, ventilating and air-conditioning sys-tems and automatic sprinkler See ASCE STRENGTH. The product of the nominal strengthand a resistance factor (or strength reduction factor).

5 DIAPHRAGM. A horizontal or sloped system acting totransmit lateral forces to the vertical-resisting the term diaphragm is used, it shall include horizon-tal bracing , blocked. In light-frame construction, a dia-phragm in which all sheathing edges not occurring on aframing member are supported on and fastened to boundary. In light-frame construction, alocation where shear is transferred into or out of the dia-phragm sheathing. Transfer is either to a boundary ele-ment or to another force-resisting chord. A diaphragm boundary element per-pendicular to the applied load that is assumed to takeaxial stresses due to the diaphragm , flexible. A diaphragm is flexible for the pur-pose of distribution of story shear and torsional momentwhere so indicated in Section of ASCE NYC NYCSTRUCTURAL DESIGN3542014 NEW YORK CITY BUILDING CODED iaphragm, rigid.

6 A diaphragm is rigid for the purposeof distribution of story shear and torsional moment whenthe lateral deformation of the diaphragm is less than orequal to two times the average story OF load . The period of continuous applica-tion of a given load , or the aggregate of periods of intermit-tent applications of the same FACILITIES. Buildings and other structuresthat are intended to remain operational in the event ofextreme environmental loading from flood, wind, snow PARTITION. A partition consisting of a finishedsurface made of fabric, without a continuous rigid backing,that is directly attached to a framing system in which the ver-tical framing members are spaced greater than 4 feet (1219mm) on load . The product of a nominal load and aload See Section load .

7 The load resulting from moving machin-ery, elevators, craneways, vehicles and other similar forcesand kinetic loads, pressure and possible surcharge from fixedor moving STATE. A condition beyond which a structure ormember becomes unfit for service and is judged to be no lon-ger useful for its intended function (serviceability limit state)or to be unsafe (strength limit state).LIVE LOADS. Those loads produced by the use and occu-pancy of the building or other structure and do not includeconstruction or environmental loads such as wind load , snowload, rain load , earthquake load , flood load or dead LOADS (ROOF). Those loads produced (1) duringmaintenance by workers, equipment and materials; and (2)during the life of the structure by movable objects such asplanters and by AND RESISTANCE FACTOR DESIGN (LRFD).

8 A method of proportioning structural members and theirconnections using load and resistance factors such that noapplicable limit state is reached when the structure is sub-jected to appropriate load combinations. The term LRFD is used in the design of steel and wood EFFECTS. Forces and deformations produced instructural members by the applied FACTOR. A factor that accounts for deviations ofthe actual load from the nominal load , for uncertainties in theanalysis that transforms the load into a load effect, and forthe probability that more than one extreme load will occursimultaneously. LOADS. Forces or other actions that result from the weightof building materials, occupants and their possessions, envi-ronmental effects, differential movement and restraineddimensional changes.

9 Permanent loads are those loads inwhich variations over time are rare or of small magnitude,such as dead loads. All other loads are variable loads (seealso Nominal loads ).NOMINAL LOADS. The magnitudes of the loads specifiedin this CHAPTER (dead, live, soil, wind, snow, rain, flood andearthquake). Combined effect of horizontal and verticalearthquake-induced forces as defined in of ASCE load due to fluids with well-defined pressures andmaximum Flood load in accordance with CHAPTER 5 of ASCE load due to lateral earth pressures, ground waterpressure or pressure of bulk Live load , except roof live load , including anypermitted live load Roof live load including any permitted live = pounds per linear pounds per square inch Snow Self-straining force arising from contraction orexpansion resulting from temperature change,shrinkage, moisture change, creep in componentmaterials, movement due to differential settlementor combinations load due to wind STRUCTURES.

10 Structures, other than build-ings, for which loads are specified in this (PART OF A STRUCTURE). The section of afloor, wall or roof comprised between the supportingframe of two adjacent rows of columns and girders or col-umn bands of floor or roof FACTOR. A factor that accounts fordeviations of the actual strength from the nominalstrength and the manner and consequences of failure (alsocalled strength reduction factor ).RISK CATEGORY. See definition for structural Occu-pancy Category. STRENGTH, NOMINAL. The capacity of a structure ormember to resist the effects of loads, as determined bycomputations using specified material strengths anddimensions and equations derived from accepted princi-ples of structural mechanics or by field tests or laboratorytests of scaled models, allowing for modeling effects anddifferences between laboratory and field , REQUIRED.