Finger Lakes Building Officials, Inc.

An Affiliated Member of the New York State Building Officials Conference

April 24, 2003

RE: Chapter 16 - code text clarifications

This is in response to your letter asking for clarification of code text where it appears to have typographical errors or require some explanations. I will reiterate contents of your letter in the form of sequential questions followed by the answers.

Please note that the Building Code of New York State (BCNYS), 2002 Edition, incorporates language of 2000 International Building Code (IBC), 2001 Amendments to the IBC, and New York State modifications of the code. The document titled "Code clarifications"and available at our web site (http://www.dos.state.ny.us/pdfs/codes/jan03clarif.pdf) contains helpful code clarification information.

Q1. Refer to Clause 1615.1 - Second paragraph - Why do you make reference to Figures 1615(1) through 1615(10) when only Figures 1615(1) and 1615(2) are included as page 318 and 319, respectively, in the code?

A1. The sentence should be amended to read ".... Figures 1615(1) and 1615(2)." Figures 1615(3) through 1615(10) were deleted in BCNYS as containing information not pertinent to design in NY State.

Q2. Refer to Table 1615.1.2(2) - First column - Should not SS be replaced by S1 ?

A2.Yes, SS should be replaced by S1 in the first column of the table. Furthermore, the references to "SHORT" (periods) in the table title and first row subtitle should be replaced by "1-SECOND."

Q3. Refer to Clause 1617.5.1 - Equation 16-49 - Should not the lower case letter "w" be replaced by the upper case letter "W" ?

A3. Yes, upper case letter "W" should be used instead of lower case letter "w."

Q4 Refer to Clause 1620.3.3 Diaphragms - First sentence in Second Paragraph - Should not the equation read "0.2IESDSwpx" ?

A4.Yes, the sentence should read "... shall not be less than 0.2IESDSwpx ." The slash "/" symbol printed should be upper case letter "I".

Q5. Refer to page 307, Note 5 - You refer to 1609.2.1 that is not shown in the code. What clause or table should be listed ?

A5. Reference to section 1609.2.1 is a typographical error. Section 1609.1.2 Minimum wind loads should be referenced.

Q6. Refer to Section 1602, page 282 - DIAPHRAGM - Without performing calculations of lateral deformation of the diaphragm versus average story drift to determine whether a diaphragm is flexible or rigid, would you classify a steel deck with 3 inches of concrete fill as a flexible or a rigid diaphragm? As stated in Clause 1616.6.1, a simplified analysis shall be permitted if the following limitation (Note 2) is made, "Buildings of any construction other than light framed construction, not exceeding two stories in height, excluding basements, with flexible diaphragms at every level as defined in Section 1602." Thus, if you classify the steel deck with 3 inches of concrete fill as a rigid diaphragm, then an "equivalent lateral force procedure" must be used.

A6. I would not attempt to classify a diaphragm as flexible or rigid without performing calculations or based solely on the assessment of stiffness of the diaphragm itself. The relative stiffnesses of the diaphragm and vertical elements of the lateral-force-resisting system determine such classification, as per code definitions of flexible and rigid diaphragm. It seems that making the initial design assumption of flexible diaphragm may be advantageous allowing for diaphragm classification with less computational effort. Regardless of the initial assumption the design analysis has to confirm its validity. If the diaphragm is determined to be a rigid diaphragm then the Simplified Analysis of Sec.1616.6.1 cannot be used. More sophisticated procedures of Sec.1616.6.2 or Sec.1616.6.3 need to be used - equivalent lateral force procedure or other as prescribed by the code.

Q7. Refer to Section 1610 - Soil Lateral Load - I have just learned that in the 2000 International Building Code, clause 1610.2 is included that requires retaining walls to be designed for a safety factor of 1.5 against lateral stability and overturning. Is there any reason why this requirement was excluded from The Building Code of New York State?

A7. The text of IBC Sec.1610.2 has been relocated to Sec.1806 Retaining Walls, subsec.1806.1 General.

This advisory opinion is rendered based upon the information provided. Administration and enforcement of the code are within the jurisdiction of the local authority. If you have questions regarding this advisory, please call me at (518) 474-4073.

Sincerely,

Lucjan J. Mitas, P.E.
Sr Bldg Structural Engineer
Division of Code Enforcement and Administration

Al03-074

Finger Lakes Building Officials Association, Inc.
3100 Atlantic Ave.
Penfield, NY 14526