School Building Evaluation and New ConstructionAug 12 2015 · 0 comments · Educational, Nishkian Chamberlain ·0
Collaborating with CSDA Design Group, the Nishkian Chamberlain team is designing replacement buildings, a gym and a multi-purpose room, for Olive Vista Middle School located within the Los Angeles Unified School District (LAUSD). The existing buildings were remaining from a 2003 Building Vulnerability Chart that required seismic strengthening or replacement due to their vulnerability during a major seismic event. Nishkian Chamberlain, assisted with a seismic study and a full site analysis of both structures to obtain Proposition 1D funding. Completion of the study determined two new buildings was the best and most economical solution.
Projects located within LAUSD, go through an arduous approval process by both LAUSD and Division of the State Architect (DSA). While DSA provides design and construction oversight, discussed in a previous blog post, LAUSD evaluates the design for constructability, project execution, and various other departments/services including maintenance and operations, sustainability, estimating, etc.
The new buildings will consist of metal deck over steel framed roof and concrete masonry unit (CMU) walls for both gravity support and lateral resistance. Each building is creatively designed and accented with large spans, up to 70 feet, and pitched roofs. To effectively achieve the architectural designs, cost effective built-up pitched steel trusses and bent wide-flange beams were utilizes to accommodate the column-free open space, as well as intended roof slopes. Additional design challenges requiring creative engineering solutions include: various roof heights and parapets, as well as clerestory windows for the gymnasium and auditorium rooms. Significant collaboration with the architectural design team was essential to successfully provide structural design solutions to accommodate the various design constraints without sacrificing the structural integrity of the design.
Also collaborating with CSDA, nearing completion of construction is the Vaughn STEM (Science, Technology, Engineering, & Math) Learning Pods. The project consists of four new buildings on four separate sites (Del Sur, Filmore, Daventry, and Eustace). These buildings are a part of the Vaughn Next Century Learning Center charter school campus in Pacoima, California.
The buildings share similar gravity and lateral systems but vary in size and shape from site to site, with each providing different challenges for the structural design. The buildings, all 2 story wood framed, utilize prefabricated wood joists (both open web and I-joists) as the typical framing members. The buildings feature large open learning spaces which necessitated the use of prefabricated joists in lieu of conventional sawn lumber due to the longer spans. The lateral force resisting system for the buildings are wood shearwalls.
The lateral design of the Eustace building, however, was particularly challenging due to the building’s shape and diaphragm configuration. The shape of the building created a horizontal irregularity for the seismic design. To satisfy the additional requirements due to the irregularity, we worked with DSA to provide an acceptable solution by analyzing the lateral system of the building using a bounded analysis per the following provision:
Per the American Wood Council, Special Design Provisions for Wind and Seismic:
When a diaphragm is not idealized as rigid or flexible, the diaphragm shear forces shall be distributed to the vertical resisting elements using a semi-rigid diaphragm analysis based on the relative stiffnesses of the diaphragm and the vertical resisting elements accounting for both shear and flexural deformations. In lieu of using a semi-rigid diaphragm analysis for distribution of story shear forces, it shall be permitted to use an enveloped analysis whereby distribution of horizontal diaphragm shear to each vertical resisting element is the larger of the shear forces resulting from analyses where the diaphragm is idealized as flexible and the diaphragm is idealized as rigid.
To learn more about Nishkian Chamberlain’s work in Southern California or if you have questions about your school seismic rehabilitation and retrofitting project, please contact our office at (310) 853-7180. You can also send an email directly to Craig Chamberlain at firstname.lastname@example.org.