Author: Karen

Jury Is In

Our Forensic Division saw a successful outcome for a rare opportunity to appear at trial on behalf of the framing subcontractor and have the jury come back completely in line with our testimony. A $30 million lawsuit related to foundation and framing issues received a less than $200,000 verdict. The 69 homes in litigation received less than $1,000 per home in framing repair costs. Many jurors admired our 3-D presentations and mentioned they reviewed the SMR videos several times before the final verdict.

Gone With The Wind – No More!

Wind-related failures over the past several years of both roof- and ground-mounted arrays of photovoltaic panels have put a damper on an otherwise booming market segment.

Solar panel builders, manufacturers, and structural engineers have struggled to understand the dynamics of these systems which have a unique geometry, weight, and method of connection to a building. With no established guidelines or codes addressing the impact of design wind loads on these types of systems, they have literally been operating in the dark as they tried to keep up with the demand for these popular energy-saving systems.

That’s about to change in 2016 when new codes are incorporated into the International Building Code (IBC / ASCE 7-10). These code changes are the result of work done over the past several years by the Photovoltaic Systems Committee of the Structural Engineers Association of California to address this problem. The committee, which is comprised of consulting structural engineers, building officials, industry members, wind tunnel research experts, members of national code committees, and the SEAOC seismology committee, developed these proposed changes to ASCE 7-10:
• Adding a Section 29.9 to address solar arrays on flat or low-slope roofs;
• Modifying Table 29.1-1 to include solar arrays;
• Adding a Figure 29.9-1 to define prescriptive wind pressure coefficients for solar arrays;
• Adding a definition of Effective Wind Area for solar arrays;
• Adding a Section 31.6 to address wind tunnel testing of solar arrays.

Establishing new industry standards with these code changes should go a long way toward removing any uncertainty in the marketplace and restoring consumer confidence about the design integrity of ground- and roof-mounted arrays of solar PV systems.

Photos showing typical wind damage to rooftop-mounted solar photovoltaic arrays: (Above left) Construction worker inspecting roof-mounted solar photovoltaic arrays on commercial building. Courtesy SolarPro |June/July 2012 / Shawn Schreiner. (Top right) Wind damage to roof-mounted solar photovoltaic arrays on commercial building due to improper installation. Courtesy SolarPro |June/July 2012 / BEW Engineering. (Above) Wind damage caused rooftop solar panels to collapse atop a residential building in Toronto. Courtesy CTV Toronto Wind damage caused rooftop solar panels to collapse atop a residential building in Toronto. Courtesy CTV Toronto Courtesy SolarPro |June/July 2012 / Shawn Schreiner


RELATED LINKS

http://www.documents.dgs.ca.gov/dsa/dsaab/csc04-12-12_agenda-Item-5B_SEAOC-WindLoad.pdf
http://www.seaoc.org/bookstore/wind-design-low-profile-solar-photovoltaic-arrays-flat-roofs-seaoc-report-pv2-2012
http://www.seaoc.org/bookstore/seismic-structural-requirements-and-commentary-rooftop-solar-photovoltaic-arrays-seaoc
http://www.solarindustrymag.com/issues/SI1304/FEAT_01_How_Structural.html
http://solarprofessional.com/articles/design-installation/wind-load-analysis-for-commercial-roof-mounted-arrays

 

2014 Excellence in Structural Engineering Awards in New Construction and The People’s Choice Award

SMR-ISD Consulting Structural Engineers, Inc. received two top awards for engineering excellence from the San Diego Chapter of the Structural Engineers Association of California (SEAOC) for its structural design of the Center for Naval Aviation Technical Training Complex (CNATT) at Marine Corps Base (MCB) Camp Pendleton, CA.

The firm, which was the structural engineering consultant for Prime General Contractor Harper Construction Company, received SEAOC San Diego’s 2014 Excellence in Structural Engineering Awards for New Construction and the People’s Choice Award.

This was a $45 million design-build project for the Naval Facilities Engineering Command (NAVFAC) Southwest for a 131,000 square foot CNATT training complex for Huey and Cobra Helicopter operations and maintenance. The  complex consists of two separate buildings – a hangar bay and an instructional / administrative facility plus an adjacent parking structure.

SEAOC San Diego presented the awards to SMR-ISD in recognition of the innovative solutions developed by the firm to address challenges presented by the architectural design and functionality of the complex.

The architectural design of the hangar area of the complex required clear, unobstructed entry for the normal operations of helicopters.  The instructional / administrative part of the complex included a large column-free multi-purpose auditorium in one wing of the building.

These design elements required the structural engineering team to develop complex horizontal truss systems for both the hangar and the auditorium to provide structural support without the use of columns.  In addition, the team needed to develop an economical and efficient plan to provide an effective truss system that was constructable.

The team relied on 3-dimensional modeling of the structure in Revit to develop workable solutions not only for the project design, but also for the means and methods of construction. For the design, the team developed an innovative “Box” truss system for the hangar bay, a challenge due to tight space constrictions.  Regarding the means and methods of construction, the team specified the use of field-bolted truss connections as opposed to a shop-welded system design which would have created a problem with the transportation of the trusses. In addition, the team had early discussions with the fabricator and steel erector to establish the type of cranes to be used and the erection strategies in order to optimize the design of the truss members.

Other challenges faced by the structural engineering team involved the Anti-Terrorism Force Protection design due to the closeness of the CNATT facility to a parking structure roadway nearby.  The four-story instructional / administrative part of the complex also needed in-depth structural analysis for the prevention of progressive collapse.

The architect of record for the project was Cass Sowatsky Consulting Architects of San Diego.