seismic design methodology - pvpowerway.com design.pdf · seismic design methodology ir 16-8, solar...
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Seismic Design Methodology
IR 16-8, SOLAR PHOTOVOLTAIC AND THERMAL SYSTEMS ACCEPTANCE REQUIREMENTS,published by California Department of General Services, Division of the State Architect, covers therequirements for seismic design of solar photovoltaic roofing systems used in construction projectsunder the jurisdiction of DSA. Section 4.2 states: “The overall panel array must be restrained. Therestraint and panel interlocking mechanism must be designed to resist sliding and pop-up resulting fromlateral and vertical seismic forces and displacements per CBC Section 1613A, and ASCE Standard 7-05,Chapter 13.”
For PV designs located in jurisdictions that follow the aforementioned Interpretation of Regulations(IR), PanelClaw uses ASCE Standard 7-05, Chapter 13 in conjunction with a seismic database from theUS Geological Survey (see image below) and PanelClaw’s ballast design criteria to develop arraylayouts combining ballast and mechanical roof attachments. Typically, mechanical attachments arerequired on a small percentage (3% to 5%) of the total Supports (PanelClaw roof top racking systemcomponent which interfaces to the roof surface). Following is the procedure used to determine themechanical attachment design based on project locations and array details.
The software used from the USGS is the “Java Ground Motion Parameter Calculator” currently version5.09a – 10/21/09.
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PC-Seismic Calculation Process 20100616
1. Project location is entered (by zip code or longitudes and latitudes) in the USGS Java GroundMotion Parameter Calculator and following parameters are output:
SS: Mapped Spectral Response – Short Period (0.2 sec)S1: Mapped Spectral Response – Long Period (1.0 sec)
2. ASCE 7-05 Chapter 11.4 is used to determine the necessary parameters to calculate the designrequirements in ASCE 7-05 Chapter 13 (see example of analysis below).
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Add: Xincheng North Road, Sanshui Industrial Park, Leping, Sanshui, Foshan City, Guangdong Province, China
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PC-Seismic Calculation Process 20100616
3. Using ASCE 7-05 Chapter 13.3 – 13.4, array details, and the known strength of the mechanical
attachments, the number of mechanical attachments required to resist lateral and vertical forces is
calculated separately. See the figure below:
a. Seismic Lateral Design Force (FP) – # roof attachments for lateral force
b. Seismic Vertical Design Force (FV) – # roof attachment for vertical force
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Add: Xincheng North Road, Sanshui Industrial Park, Leping, Sanshui, Foshan City, Guangdong Province, China
Tel: +86-757-8766-2928 Fax: +86-757-8766-2921Website:www.pvpowerway.com/en
PC-Seismic Calculation Process 20100616
4. Final quantity of roof attachments required for the design is determined by taking the larger ofthe two numbers (lateral and vertical). The results are incorporated into the array layout (seeexample below).
Example Array Layout (Supports with Mechanical Attachments are shown in Yellow)
Example Array Detail
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Add: Xincheng North Road, Sanshui Industrial Park, Leping, Sanshui, Foshan City, Guangdong Province, China
Tel: +86-757-8766-2928 Fax: +86-757-8766-2921Website:www.pvpowerway.com/en
PC-Seismic Calculation Process 20100616