Return to index: [Subject] [Thread] [Date] [Author]

Re: Mechanical Equipment - Live or Dead/AFTER ANSI A58.1-82

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Dennis,

Before I answer your question I would first draw your attention to ANSI
A58.1-82 (now replaced by ASCE-7/95 ??) which categorises DEAD & LIVE loads
as follows:

 1) DEAD LOADS

    - It comprises the weight of all permanent
      construction including, walls, floors, roofs,
      ceilings, stairways & Fixed Service
      Equipments and the net effect of prestres-
      ing.

   As per clause 3.3 of ANSI A58.1-82, the
   Fixed Service Equipments include:

    - plumbing stacks & risers
    - electrical feeders
    - HVAC (heating, ventilation & airconditio-
      ning) system.

In the light of the above, answer to your first question is: The equipment
loads are DEAD LOADS.

And, as for your second question, it is no more valid now because its not a
LIVE LOAD.

However,  speaking strictly on the basis  of actual design practice that Iam
familiar with (my own background); in the cases where we have specific
mechanical loads on the roof (like ACCU, AC PACKAGE UNITS, CHILLERS, AIR
HANDLING UNITS ETC) these loads are taken care of as DEAD LOADS.

But in the cases where we donot have such heavy mechanical loads on the
roof, we always take an allowance of some unforseen mechanical loads. These
are taken as 0.50 KN/M2 or 10 psf and are always taken as LIVE LOADS. This
live load basically takes care of:

   - any collateral load, like, exposed
     piping work on the roof,
   - loads due to maintenance workers,
   - or any other heavy construction
     equipments, tools & plants temporarily
     placed over the roof.

What I see is this approach is corroborated by ANSI A58.1-82; follow the
description of the LIVE LOADS as per ANSI.

  2) LIVE LOADS

  -  Live loads are  those loads produced by
     the use & occupancy of the building or
     other structures and donot include
     environmental loads such as wind, snow
     rain & the earth quake loads; or dead
     loads.,

  -  Live loads on a roof are those that are
     produced due to:

      - during maintenance by workers,
        equipment and materials,
      - during the life of the structure by
        movable objects such as planters and
        by people.

I hope Iam able to throw some light on the issue Which I hope you would find
useful.

Regards,

SYED FAIZ AHMAD; MENGG, MASCE
SENIOR STRUCTURAL ENGINEER
SAUDI OGER LTD
RIYADH, SAUDI ARABIA.


From: "Dennis Wish" <dennis.wish(--nospam--at)verizon.net>
Reply-To: <seaint(--nospam--at)seaint.org>
To: <seaint(--nospam--at)seaint.org>
Subject: Mechanical Equipment - Live or Dead
Date: Mon, 11 Feb 2002 18:21:35 -0800

I know this is a dumb question and I should know better, but let me ask
it anyway:

Is a roof mounted A/C unit considered a Live or Dead Load?
Is it added to the existing Live Load or does it replace the live load
normally applied to that location?

Dennis S. Wish, PE
California Professional Engineer
The Structuralist.Net Information Infrastructure

 <http://www.structuralist.net> Website:
 <http://www.structuralist.net> http://www.structuralist.net






SYED FAIZ AHMAD; MENGG, MASCE
SENIOR STRUCTURAL ENGINEER
SAUDI OGER LTD
RIYADH, SAUDI ARABIA.


_________________________________________________________________
Send and receive Hotmail on your mobile device: http://mobile.msn.com


******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********