With an increased focus on resiliency as well as emphasis on the reuse of existing buildings, understanding when a building requires a seismic retrofit is becoming ever more important and can often not be so simple an answer…
Our Nishkian Dean team has been following the efforts of the URM Building Policy Committee and Portland City Council to develop a mandatory seismic retrofit policy for unreinforced masonry (URM) buildings. This post is intended as an update to these previous posts, and to cover recent news.
We recently reported on a few outcomes from the Portland City Council meeting on June 13, 2018: a new proposal for the placement of warning placards on URM buildings, and one to require landlords (URM building owners) to notify their tenants that they reside in a URM structure. Read more here: https://www.nishkian.com/portlands-urm-seismic-retrofit-requirements-on-hold-for-now/
The resolution that passed at the June 13th Portland City Council meeting states that, starting in March 1, 2019, URM buildings that have not been retrofitted must post placards that “state clearly in a conspicuous place at the entrance of the building printed in not less than 30-point bold type: ‘This is an unreinforced masonry building. Unreinforced masonry buildings may be unsafe in the event of a major earthquake.’” 
Since that meeting, the Portland Bureau of Development Services has been working to write an official ordinance that would require signs and tenant notifications for URM buildings, among other items.
In summary, the ordinance requires a placard on all URM buildings that have not been retrofitted to prevent collapse in the event of a “major earthquake.” The durable placard needs to be sized 8”x10” with lettering in a 50-point bold font, placed in a conspicuous location on the exterior at the main entrance with the following message in capital letters: “This Building is an Unreinforced Masonry Building. Unreinforced Masonry Buildings may be unsafe in an event of a Major Earthquake.” 
Additionally, the ordinance requires that URM building owners directly notify tenants/renters through rental agreements that their building is an unreinforced masonry building, which may be unsafe in an event of a major earthquake. 
From the City of Portland website, the ordinance requires URM owners to post a placard according to the following timeline:
• Publicly-owned buildings: On or before May 1, 2019
• Non-profit buildings: On or before November 1, 2020
• All other buildings: On or before November 1, 2019 
Another part of the ordinance is that URM building owners are required to strengthen existing seismic triggers for their buildings. This may include:
1. Roof replacement. (Removal of greater than 50% of total roof area within a 15-year period requires wall anchorage for both in plane and out of plane forces and parapet bracing.) 
2. Costs of alterations or repair. (When costs associated with building alterations or repair in a five-year time period or fifteen-year time period exceeds the square-foot costs outlined in the ordinance, entire building must be improved to resist seismic forces to meet ASCE 31 41 criteria.) 
Nishkian Dean will continue to monitor the development of this important issue that affects many of our clients. Please contact us if you have questions on how these policies may affect your projects.
1. Proposed URM Placarding and Tenant Notification Ordinance:
2. Portland City Council Resolution No. 37364: https://www.portlandoregon.gov/auditor/article/689174
By Robert A. Aman, PE, SE
The Seismic Rehabilitation Grant Program (SRGP) has a new application round that opened July 2, 2018, and closes on November 16, 2018, at 5:00pm. The SRGP is a State of Oregon biannual competitive grant program the provides funding for the seismic rehabilitation of existing critical public buildings, including public K-12 schools and emergency services facilities such as hospitals, acute inpatient care facilities, fire stations, police stations, 9-1-1 centers, and Emergency Operations Centers.
Nishkian Dean has been closely following the efforts of the URM Building Policy Committee and Portland City Council regarding their plan to develop a mandatory seismic retrofit policy for unreinforced masonry (URM) buildings.
The article titled “At Risk in a Big Quake: 39 of San Francisco’s Top High Rises” in The New York Times’ California Today section, June 14, 2018 edition by reporter Thomas Fuller, wrongly included the 100 Van Ness project as one of the high-rise buildings at risk in a big earthquake.
By Edwin T. Dean, PE, SE
Existing buildings in the City of Portland are subject to unique requirements that govern what seismic strengthening improvements need to be implemented. These requirements have evolved with the heightened recognition of seismic risk within the region, advancements in seismic engineering technologies, and the movement to increased seismic resiliency, which is expected to provide improved performance of the buildings where we live, work, and shop when subjected to strong ground shaking.
Since its construction in 1928, the historically significant Chapman Court structure has withstood the test of time in the heart of the densely populated Wilshire Center in Los Angeles, CA. This building is a unique example of Spanish Colonial Revival architecture with intricate Churrigueresque detailing, by a prominent Los Angeles architectural firm during the 1920s; Morgan, Walls & Clements. The original use, a sample of how history repeats itself, was a mix of retail and live/work spaces with the retail spaces on the ground floor and the studios and residential spaces adjoining a central corridor on the upper floors.
By Edwin T. Dean, PE, SE
How devastating would an earthquake be to the Portland metro area? A recent report on the Earthquake Regional Impact Analysis for Clackamas, Multnomah, and Washington Counties, Oregon was published by the Oregon Department of Geology and Mineral industries (DOGAMI) seeks to answer that question. The report is an assessment of the damage and casualties that could result from a major earthquake in the region.
Remember the destruction that occurred in 1994 when Northridge suffered a devastating 6.7-magnitude earthquake: freeways crumbled, apartment buildings collapsed and, as a result, more than 60 people were killed, 9,000 people injured and $25 billion in damage was reported. It’s a lesser-known fact that an estimated 49,000 housing units in Northridge alone were rendered uninhabitable from the Northridge quake.
By Serena Gilles, P.E.
The Oregon Seismic Rehabilitation Grant Program (SRGP) was created to help fund seismic upgrades for educational institutions and emergency services buildings including hospitals, fire stations, and police stations. The purpose is to reduce losses in the case of a major seismic event, which has been predicted to have a 40% chance of occurring along Oregon’s Pacific coastline within the next 50 years. This program focuses on the safety of K-12 children and their educators, first responders, and hospitals that are expected to be operational following an earthquake. Higher education facilities are also eligible for funding.
Read the latest developments on this subject at https://www.nishkian.com/portlands-urm-seismic-retrofit-requirements-on-hold-for-now/
A January 2018 update to our blog post from July 2017
Nishkian Dean previously reported on the URM Building Policy Committee back in July, which you can read here. This shorter post is intended to be a supplement to the original post, and to cover items not addressed in the previous article.
The URM Building Policy Committee had a final meeting on November 8, 2017 and completed a final draft of their report and recommendation in December, which the Portland City Council is likely to review in early 2018.
In summary, the Committee’s proposal is to require seismic strengthening of URM buildings using a tiered approached based on the building’s use and occupancy. The only exceptions to these recommended requirements are for one- and two-family homes and URM buildings that were previously seismically strengthened to an acceptable defined standard, as well as buildings serving religious functions or other buildings owned by non-profits that are not being used as schools. The exemption for Class 3 churches and other buildings used by non-profits would require that a placard noting the earthquake risk be placed at or near the entrances.
By Edwin T. Dean, PE, SE
Having completed the initial designs for the innovative CoreFirst system, we at Nishkian Dean believe that it is a viable alternative to doing nothing and accepting fate when it comes to the next earthquake that may devastate Oregon buildings and put occupants in harm’s way. There is little argument that a full seismic strengthening of a building is the best solution, but for many building owners, it is simply not an expense that they can afford. If a full seismic upgrade is not a financially viable option, an alternative that would potentially provide a robust sanctuary to shelter occupants as the building around them shakes apart during a seismic event is a good one.
Read the latest developments on this subject at https://www.nishkian.com/portlands-urm-seismic-retrofit-requirements-on-hold-for-now/
By Edwin T. Dean, PE, SE
Unreinforced masonry (URM), or the use of stone or brick masonry for structural walls, was a common approach in Portland building construction from the late 1800s to as recently as the 1950s. These buildings range in size from small one-story residences to large 10- or 12-story buildings, most with wood-framed floors with some structural steel or cast-iron components. Many of these buildings are historically registered and represent a valuable part of the City’s cultural heritage. Several are public buildings used for government operations or public schools. The characteristic of concern for this type of building construction is that they are extraordinarily vulnerable to earthquake damage, where even moderate ground shaking could result in partial collapse.
Earthquake occurrences in other West Coast cities, such as Loma Prieta in 1989 in the San Francisco Bay Area and Northridge in 1994 near Los Angeles, have demonstrated that this type of construction is susceptible to devastating collapse and associated loss of life and property damage. There were many URM buildings that were damaged in these events, including those that had been seismically strengthened. This damage represented a very significant economic cost, though fortunately not a large number of deaths and URMs did not represent the deadliest type of buildings. These cities now have URM mandates: in the Bay Area, this was largely put into place after the Loma Prieta event, and in Los Angeles it had been implemented prior to the Northridge event.
The Los Angeles Times proclaimed the start of a “New Frontier” for earthquake safety: a phenomenon kicked off by the city of Santa Monica, which recently adopted the most comprehensive seismic retrofit ordinance in the nation.
An Owner’s desire to evaluate the seismic performance of an existing building varies. Some national, regional and local Owner’s simply have a genuine concern for knowing the seismic vulnerability of their buildings. Other reasons Owners perform evaluations can include an adopted City Ordinance, a policy trigger for analysis or modification of the building, a requirement for a financial transaction, or buildings with State employee tenants requiring special analysis, just to name a few.
Since the passing of the LA City’s Ordinance in October of 2015 to improve the seismic safety and community resilience of the City by requiring retrofit of over 15,000 soft story and non-ductile concrete buildings, the City of Santa Monica (approximately 16 miles west of LA) appears to be the next major city to adopt a similar but more expansive building type ordinance.
The Santa Monica City Council, on February 14, 2017, tentatively approved, unanimously, to adopt the nation’s most extensive seismic retrofitting effort, which could require safety improvements to as many as 2,000 earthquake-vulnerable buildings. For the ordinance to be approved, the City Council will need to pass the law a second time in the next month. If the measure receives that affirmation, the proposal will become law 30 days later.
Santa Monica’s safety rules would go beyond what Los Angeles has done by requiring not only wood-frame apartments and concrete buildings to be retrofitted, but also Concrete Tilt-Up, Unreinforced Masonry and Steel-frame structures.
By Dave Beh
Structural engineers design the primary structure to withstand seismic forces, as a minimum, as outlined by the design code. However, during an earthquake people can be injured and costly damage can result by falling non-structural components such as; kitchen hoods, bookcases or mechanical/electrical equipment. The code also requires seismic anchorage for certain non-structural components but these can sometimes get overlooked by designers/owners/plans examiners that simply don’t yet have the information or are unaware of the requirements.
Read the latest developments on this subject at https://www.nishkian.com/portlands-urm-seismic-retrofit-requirements-on-hold-for-now/
The City of Portland is laced with seismic faults and is vulnerable to the looming Cascadia subduction zone earthquake, which could have a magnitude as high as 9.0. Despite this risk, Portland has one of the highest concentration of unreinforced masonry (URM) buildings in the Pacific Northwest. URM buildings are particularly vulnerable to potential catastrophic collapse in earthquakes. To alleviate this risk, the Portland Bureau of Emergency Management (PBEM) convened a series of committees to propose new URM seismic retrofit standards, which are currently under deliberation with the goal of passing the new standards in the City Council in 2017.
Originally constructed as a medical office building, this four-story, semi-circular structure will be the new home to Nova Academy located in Santa Ana, California. In order to meet the increased design criteria required to convert the existing building to a school building, a series of fluid viscous dampers were installed into the structure to supplement the existing pre-Northridge steel moment frame system.
Over the past few months, major earthquakes have shaken areas around the world. The 7.8-magnitude earthquake that struck Ecuador on April 16 has killed at least 659 people, and more than 27,732 others were injured. The quake, Ecuador’s worst in decades, destroyed or damaged about 1,500 buildings, triggered mudslides and left some 20,500 people sleeping in shelters, according to the government. Japan was also hit with a series of earthquakes last month killing at least 49 people and injured about 3,000 others in total. Severe damage occurred in Kumamoto and Ōita Prefectures, with numerous toppled buildings, collapsed bridges and shredded structures into pile of debris.
The reconstruction of the F&H Building on 211 East Main Street was a major contribution to the revitalization of downtown Bozeman, its place in the community and local economy. The process of rebuilding also played a major part of the healing process for downtown Bozeman. Seven years ago in the morning of March 5, 2009, a gas main explosion and fire rocked the snow-covered downtown Bozeman, destroyed five historic buildings and businesses on the north side of the 200 block of East Main Street, and killed one young woman. Eleven months after the explosion, two Bozeman businessmen submitted plans to build a new three-story structure, which would fill more than fifty percent of the gaping hole and rebuild. Rockin R Bar owners, Ralph Ferraro and Mike Hope, named the new building the “F&H Building.”
Renters and apartment owners must equally share the financial burden of earthquake retrofitting, the Los Angeles City Council agreed Wednesday, January 13, 2016, capping a more than year-long debate that allows the city to begin implementing the most comprehensive mandatory seismic laws in the nation.
Following many housing studies and heated meetings with landlord and tenant groups, city staff proposed a compromise that the City Council unanimously voted to move forward: Owners can pass half the retrofit costs to tenants through rent increases over a 10-year period, with a maximum increase of $38 per month.
Aging and historic structures bring a style of their own into the skyline as they mesh with the sleek lines and polished surfaces of modern construction. Old age, poor or nonexistent drawings, past renovations, and other unknown conditions mean bringing these structures up to current code represents a unique challenge. The design team should be aware of the most up to date code standards and how they can be utilized in the project jurisdiction. American Society of Civil Engineers (ASCE) 41-13 is one such code that deserves attention.
Each year, an earthquake preparedness event known as the Great Shakeout Earthquake Drill takes place around the globe. The event provides an opportunity for people in homes, schools, businesses and other organizations to practice what to do during earthquakes. Earthquake articles like the one from The New Yorker also remind us how important it is to retrofit homes and buildings and to make sure homes, businesses, families, and coworkers are prepared.
As structural engineers, and with the recent large earthquakes around the world, the latest earthquake disaster movie moving out of theaters–and yesterday’s 4.0 magnitude earthquake that jolted East Bay residents awake, we get a lot of questions about what to do during an earthquake. We have gotten this question from family members and friends, and even a stranger at a bar who overheard our conversations. Surprisingly, I have been able to use a scene in the movie San Andreas to better illustrate the answer this question: duck, cover, and hold.
It has been shown that the number one cause of harm during an earthquake in the U.S. is falling objects. These are items like lights, signs, ceiling tiles, and broken glass. To avoid getting hurt by these objects, it is the consensus of the engineering society to duck, cover, and hold. Specifically, get under a surface, cover your head, and hold on to the legs of the surface. This way you will be well hidden from falling objects, and the surface won’t roll or slide away from you in the event of large shaking.
After an extensive 16-month renovation and seismic retrofit the Joseph Phelps Vineyards Guest Center re-opened its original winery building to visitors this summer. Originally designed by renowned architect John Marsh Davis in 1973 the majority of the historic building’s interior was removed, an interior floor was added, and the old building seismically upgraded. The Phelps family and the executive team collaborated with Baldauf Catton Van Eckartsberg (BCV Architects), Brandenburger Associates AIA, Cello & Maudro Construction Company (General Contractor), and Nishkian Monks to repurpose the interior winery spaces, enhancing the guest experience, while maintaining the building’s existing redwood exterior design.
Timing and logistics were key challenges as work occurred with hundreds of guests visiting the winery campus located in California’s Napa Valley. The architects focused on creating lighter spaces and installing modern utilities, while preserving the classic character of the structure. One of the primary challenges of the project was the seismic reinforcement and safety of the 40 year old structure.
A recent article in The New Yorker entitled “The Really Big One: An earthquake will destroy a sizable portion of the coastal Northwest. The question is when.” has caused a media storm with outlets across the country now talking about, what was for many, a previously little-known fault line, the Cascadia Subduction Zone, and its anticipated impact on the Pacific Northwest.
The Cascadia Subduction Zone refers to a fault line just off the Oregon/California/Washington coastlines, paralleling a series of volcanic mountains called the Cascade Range, where the North American and Juan De Fuca tectonic plates meet in the Pacific Ocean. These tectonic plates are so tightly wedged against one another and the pressure is so intense that when they eventually slip along its length, scientists are anticipating a 9.0, or higher, magnitude earthquake accompanied by a potentially 45-foot tall tsunami that will batter the north Pacific coastline from California to Canada. And, according to those same scientists, we are 315 years into a 243-year recurrence cycle.
The Cascadia Subduction Zone, an area where tectonic plates off the coast of Oregon typically grind and slip to relieve pressure, have become “locked.” All of this pressure building along the fault line must be released at some point, which has significant implications for risk of major earthquake in the Pacific Northwest.
In response to this, Oregon’s Seismic Rehabilitation Grant Program (SRGP) was initiated by Oregon Emergency Management to fund earthquake retrofitting and seismic upgrade efforts for schools, higher-education institutions, and emergency services buildings.
The most obvious threat from earthquakes is physical damage to vulnerable buildings. Buildings can be built to withstand strong earthquake shaking, but because of the increased costs associated with such enhancements, most are not. Many people believe that modern Building Codes ensures that our buildings will not be severely damaged in earthquakes. Current Building Codes, however, are designed to maximize life-safety, and not to minimize building damage. These standards mean that while buildings are designed to remain standing and protect occupants from collapse, they are not designed to necessarily remain usable or prevent damage after strong earthquakes. A strong earthquake in Los Angeles could cause some older buildings to collapse, but would leave many more standing but unusable or in need of repairs, which would close businesses, deny residents access to goods and services, and devastate our economy.
“Resilience by Design” presents the recommendations of the Mayoral Seismic Safety Task Force (headed by Dr. Lucy Jones of the United States Geological Survey as his Science Advisor for Seismic Safety). These recommendations address the city’s greatest vulnerabilities from earthquakes with significant and attainable solutions to:
Earthquakes versus hurricanes…which natural disaster proves to be more damaging to buildings? This is an interesting question to compare and contrast. Each event affects buildings in fundamentally different ways, yet there are some striking similarities, as well. Let’s examine them.
Earthquakes are strong ground movements that result from ruptured crustal faults. And although regions that are seismically active and prone to earthquakes are largely known and geoscientists have mapped at least the potential for strong ground motions throughout the United States, earthquakes are unpredictable. The strength of the ground shaking below a particular building is a function of the distance from the rupture (both depth and distance along the surface), the type of soil the building sits on, and, of course, the size of the rupture/the extent to which the fault fractures during the event. The ground accelerations manifest themselves in forces within the building (remember from science class, F = ma where “m” is the mass of the building and “a” is the ground accelerations). Some of the strongest ground accelerations mapped by the USGS can be found in:
More and more discussions these days are focusing around the resiliency of our communities. How well are the cities in which we live prepared to react to emergencies? In the Structural Engineering community here on the West coast, we tend to think of these related to our response to earthquakes, but this can also related to hurricanes, flooding, tsunamis, fires or other significant events. Community resilience has to do with many different things from our building structure survival to emergency response teams to communication lines to water distribution and other lifeline critical elements.
One major aspect to the community resiliency discussion is the ability of our existing building stock to survive a disaster. An effort is underway to better track and categorize how safe each and every building is that we live, work and play in every day. A relatively new organization, The U.S. Resiliency Council (http://www.usrc.org/) is working to address this topic. This group is developing a system to measure the risk and resiliency of our existing building stock. Ratings will benefit Owners, Lenders, tenants and government jurisdictions by increasing the value of well-designed buildings and providing a means for quantifying risk. See the chart below of an example of how these ratings could be posted on a building.
The U.S. Geological Survey’s (USGS) Working Group on California Earthquake Probabilities estimated in 2007 that there is a 63% probability of at least one magnitude 6.7 or greater quake, capable of causing widespread damage, striking the San Francisco Bay region before 2030. There is a 67% probability of a similarly sized earthquake striking the Southern California region within the same period (http://www.scec.org/ucerf2/).
Seismic retrofitting a building in California is a great way to reinforce the long term durability of a building before the next earthquake hits. It also makes the structure safer by protecting the occupants from potential loss of life. A retrofitted structure can generally withstand more movement than a non-retrofitted structure and this will help business owners protect their assets, reduce liability and lower the risk of catastrophic loss.
Nestling high in the foothills of Mount Everest lies the village of Phortse, a community of Sherpas working together to develop their village. One of the ongoing community project work is the Khumbu Climbing Center, a project of the Alex Lowe Charitable Foundation. In 2003 the Alex Lowe Charitable Foundation launched the Khumbu Climbing Center to teach basic mountaineering and climbing skills to Sherpas who often make their living guiding on Mount Everest with little or no climbing experience. The climbing center project is being built in honor of Alex Lowe who was widely considered one of the finest all-around mountaineers when he was killed by an avalanche in Pakistan in 1999. The building will be the first structure in this region to be engineered professionally to reduce structural damage from an earthquake and prevent roof collapse due to heavy snow load. Also unique to the region is the building’s passive solar design considerations. The building will be heated entirely by passive heating techniques. The Alex Lowe Charitable Foundation collaborated with the community of Phortse, Montana State University, architect and MSU professor Michael Everts, and structural engineer Ty Monks, P.E., LEED A.P. of Nishkian Monks PLLC in Bozeman, Montana to design and build this new school located in the rural hillsides of Nepal. Once completed, the 3,000-square-foot (279 square meters) building will house classrooms for teaching technical climbing and rescue skills, an indoor training wall, a library, storage room for gears, solar showers, and community center.
The 6.0-magnitude earthquake that struck at 3:20 am on Sunday, August 24, 2014 near American Canyon in the San Francisco Bay Area has once again brought attention to earthquake preparedness. According to various local reports, the earthquake injured about 200 people and caused at least $1 billion in damage and losses. San Francisco Business Times’ Chris Rauber reported that overall damages could hit as high as $4 billion.
The Napa Valley earthquake was the first significant test of the Bay Area’s preparedness since the 1989 Loma Prieta earthquake. In the 25-years since the devastating Loma Prieta earthquake, great strides have been made in encouraging seismic retrofitting. However, there are still far too many vulnerable buildings in our seismically active regions. If you’re a long-time resident in California or the Pacific Northwest chances are that you’ve seen firsthand the dangers that older “soft story” type structures and unreinforced masonry buildings pose. We cannot stress enough that retrofitting older structures is crucial to saving lives before the next “big one” hits. Nishkian engineers have extensive experience in seismic upgrades and retrofitting, and keep up to date with ever changing building codes and state-of-the-art solutions to address these challenges. If you have any questions about seismic upgrades and your building, please contact any of our offices.
Earlier this year we wrote about several cities across the state of California that were in the process of enacting new legislation regarding retrofit of certain types of older buildings. While San Francisco passed legislation specifically for soft-story structures, Los Angeles and Santa Monica have been working to put new legislation in place. Here we’ll discuss the latest progress in the City of Santa Monica.
On February 11th, 2014 the City of Santa Monica put their latest Seismic Retrofit Plan in motion. At this council meeting the Department of Planning and Community Development was allocated $105,000 to launch the first of three phases of a comprehensive seismic safety program that will address building vulnerabilities within the City of Santa Monica.
Currently, in the City and County of San Francisco, there are over 24,000 children attending private K-12 schools. These schools play a vital role in San Francisco communities and in the education of future generations. As such, the buildings that make up these schools play an important role in protecting students. Private schools in general are held to a lower building code standard than public schools. Plans for public school are required to be reviewed by the Division of State Architect and designed by a licensed structural engineer, while private schools are only designed by a licensed professional engineer. The inspection and material testing requirements are also much more lenient in private school building construction than in public schools. These requirements, coupled with an aging building population, can result in lower seismic safety of private school building.
The Private Schools Earthquake Safety Working Group started meeting in late 2012 to discuss and explore the current state of private school’s building seismic safety. The Working Group was made up of parents, school faculty, engineers, city officials, and concerned citizens who met for over a year to assess the best course of action in regards to the seismic safety of buildings. The Working Group’s recommendation to the City of San Francisco is to implement a mandatory seismic evaluation ordinance for all private schools within the City and County of San Francisco.
On the U.C. Berkeley campus, directly adjacent to the California Memorial Stadium, sits Maxwell Family Field. The existing multi-use playing field has been temporarily removed in order to build a two story parking structure and new elevated field in its place. The project will provide an updated sports field and 450 much needed parking spaces to the UC Berkeley campus. Pacific Union Development Company, with architect Gould Evans, contractor Build Group, and Nishkian Menninger, has created plans that allow this structure to be built on this challenging site.
Long ago, the site was once a creek bed. During the development of the campus, the creek was turned into a set of large culverts, and filled in to provide a flat surface. This type of loose fill makes building a seismically safe structure more difficult. Similar to the challenges of building on bay mud in San Francisco, the ground could liquefy during an earthquake, resulting in amplified forces on the structure. This condition is exacerbated by the presence of the Hayward fault, which runs just a few hundred feet away from the site.
Located in the Crow’s Nest development at Sugar Bowl Ski Resort in Tahoe, California this 5,600-square-foot, three-story, unique ski-in/ski-out chalet is truly a one-of-a-kind custom home. Nishkian Monks PLLC participated in the project as the structural engineer of record, working directly with San Francisco-based architectural firm Baldauf Catton Von Eckartsberg/BCV Architects, and general contractor Mt. Lincoln Construction of Truckee, California. Situated in the Sierra Nevada mountain range where maximum expected design snow depth is 16 feet – equating to 380 pounds per sq.ft. of snow weight, construction of this luxury residential building posed challenges due to the site and program constraints. Additionally, the site is located at one of Sugar Bowl’s highest reaches – higher than many of the resort’s ski lifts, and situated in a region of high seismicity. BCV Architects challenged Nishkian Monks with designing a multi-folded, double sloping plane roof with oversized overhangs out of wood framing that could support the extreme roof snow loads. Through numerous design iterations and collaboration with BCV, Nishkian Monks successfully achieved a structural design for BCV’s striking exposed wood purlin roof. The roof purlins were arranged in such a fashion so as to emanate from the center of the chalet when viewing the house from any side.
After the Northridge Earthquake in 1994, seismic retrofit was on the minds of many Californians. Within several years of that event, the Santa Monica City Council introduced new Retrofit Ordinances to address and mitigate vulnerabilities of these existing, older buildings. The City Council ordered its staff to locate potentially vulnerable types of wood, concrete, masonry or steel framed buildings and require the owners to strengthen or demolish them.
At nearly the same time, the Los Angeles City Council discussed mandatory retrofitting for soft-story apartments as well. Hal Bernson, the city councilman who proposed the measure back then, said in an interview that property owners fought him “tooth and nail.” In the end, the proposal never passed.
With the recent 20th anniversary of the Northridge Earthquake, retrofitting of these at-risk structures is again being discussed. At the forefront of these discussions are cities such as Santa Monica, Los Angeles and San Francisco. And requirements for retrofitting are beginning to be passed this time around.
Twenty years ago today on January 17, 1994 at 4:31am, a 6.7 magnitude earthquake of about 10 seconds centered in the Northridge area shook much of Southern California awake. The Northridge Earthquake would soon register over 1,000 aftershocks with the strongest ground motion recorded reaching some 220 miles from the epicenter. The quake also caused more than 11,000 landslides which blocked roads and damaged and destroyed structures. It is recorded as one of the costliest natural disasters to hit the United States with over $40 Billion in damages sustained.
As a result of the quake, many changes occurred in building codes, public awareness, preparation and public policy. One of the causes of loss of life was the collapse of the Northridge Meadows Apartment Building which contained a “soft story”, where the first story (consisting of parking) lacked shear walls or lateral force resisting elements along one edge of the building. During the earthquake, this level gave way and was crushed under the weight of the second and third floor apartments. 16 people tragically lost their lives in this one building.
Do you remember seismic zones? Depending on how long you have been involved in the building industry you may or may not remember seismic zones. May be you had experience with Zone 4 rated components or even today we get asked to design to Zone 3 or other seismic Zone requirements.