Building codes require that buildings be classified based on the risk to human life, health, and welfare associated with their damage or failure. Minimum design loads, maximum allowable story drift criteria, and lateral force resisting system limitations are derived based on this classification. Building codes in the U.S. generally reference the ASCE 7 provisions for appropriate building classification criteria.
The idea of designing different types of buildings to different seismic force levels based on their “risk” is not new. The Building Code utilized increased Importance Factors for schools and hospitals for many years to provide a greater degree of resilience in certain structures. In the early 2000’s the first edition of ASCE 7 utilized the term “Occupancy Category” to define a buildings classification. However, the term “occupancy” is primarily used with fire/life safety issues and only implicitly defined risks associated with structural failure of a building. Consequently, the 2010 version of ASCE 7-10, introduced the term “Risk Category” in lieu of “Occupancy Category” to distinguish between the two considerations. Per commentary section C1.5.1 in the ASCE 7-10:
“The Risk Categories in Table 1.5-1 are used to relate the criteria for maximum environmental loads or distortions specified in the ASCE 7 to the consequence of the loads being exceeded for the structure and its occupants.”
Table 1.5-1 the ASCE 7 defines four distinct Risk Categories:
Risk Category I
Structures that are normally unoccupied and would result in negligible risk to the public should they fail. These include structures such as barns and storage shelters.
Risk Category II
This category contains all buildings and structures not specifically classified as conforming to another category. The majority of structures such as residential, commercial, and industrial buildings are included in this category.
Risk Category III
This category includes buildings and structures that could pose a substantial risk to human life in case of damage or failure. Structures under this category include:
Careful assessment of the Risk Category for a new project is required prior to design. Minimum design loads for snow, ice, and seismic considerations are greatly influenced by the importance factors defined in Table 1.5-2 of the ASCE 7 for different Risk Categories:
Additionally, buildings located in regions with high seismicity are particularly sensitive to Risk Category classifications. Per Chapters 11 and 12 of the ASCE 7 Risk Category selection has major impacts on:
For this reason it is important to note that changing a buildings occupancy can result in significant changes to gravity (in snowy/icy regions) and lateral designs. Careful consideration must be given to projects involving existing structures whose occupancy change triggers a bump from a lower Risk Category level to a higher one. The existing lateral and gravity systems may require retrofits to accommodate stricter structural system limitations, increased load demands and stricter allowable drift criteria.
In addition to ASCE 7, individual states have further defined and clarified Risk Categories for different buildings and each state’s Building Code should be considered and referenced when determining a buildings Risk Category. It is also helpful to work with a design professional such as an Architect when determining number of occupants in complex buildings made up of multiple occupancies and where total number of occupants may require different Risk Categories. In fact different Risk Categories can be specified within the same building structure in special conditions.
The Nishkian team has years of experience with thousands of projects across all Risk Category types. Should you have any questions on an upcoming or current project, please do not hesitate to contact any of our offices.
In our blog this week we will revisit the very important topic of the Structural Engineer during Construction. We discussed this subject in a previous blog The Structural Engineer’s role in Construction – From design through CA which highlighted several aspects of this step in a building’s evolution:
In this Part II Blog of the Structural Engineer’s role during construction, we examine several additional key pieces to a successful construction project. From setting up an initial kickoff meeting prior to the start of construction to providing an opportunity for younger engineers to see what they design to collaborative resolution of field issues to final visits and developing as-builts, construction is an important time for the Structural Engineer to be engaged and on site!
One item that’s extremely critical in the course of construction is getting off on the right foot. A kickoff meeting at the beginning of the project is critical to getting the entire team on the same page from the start. There should be a discussion of the RFI process and schedule of submittals and understanding of the expectation for response. And what is the process for responding? Will communication go through the Architect always? Should the General Contractor be copied on communication before official responses go out? Is there a tracking system in place where all the RFI, Submittal, meeting minutes, etc. are kept? These are often not always the same answers on each project and they should be thoroughly worked out at this kickoff meeting. Another good topic is discussing and confirming the steps at which site visits and Structural Observations are to be performed during the project. Establishing the process early with key team members involved issues is all to the benefit of the overall project and will go a long way to keeping things moving forward and on schedule.
Construction is a great learning opportunity for younger engineering staff to get on-site to “kick the tires” and see what we’re designing. As engineers, we often find ourselves behind a desk preparing calculations and running computer analysis without the opportunity to get a chance to see how things are physically built. A line drawn on a paper is often very different in appearance, shape, size, and relational context to the rest of what is being built in the field. Being able to go and see that on site is extremely important and a great time to get engineers out to interact with the elements we design and with the people who build it. It also gives us the very real understanding that drawing our plans, section, elevations and details to scale is extremely important. We’ve all seen in the field those times when the detail drawn on paper did not appear to be as intended when built in the field and this can, at times, be attributed to “not to scale” details. Site visits by younger engineers helps improve their skills for the next project!
Often times in construction there are elements that are not fully known until construction has begun. This can be site conditions after demolition, as-built plans that were relied upon, but ultimately did not match field conditions, or Owner direction changes during construction. Unforeseen conditions require a collaborative approach and typically rapid resolution process to make changes while construction is ongoing. In an unforeseen condition situation when an issue is identified as different than what was drawn on the drawings and the team needs to deal with it, collaborative coordination between Contractor, Architect, Owner, Structural Engineer and/or other disciplines, as required, is extremely important in the process of not only resolving the issue but resolving it as quickly as possible with as minimal design and cost impact to the overall project. Part of this process may involve a review of changes to the plans as well as changes to the contract where change orders are reviewed for the Owner from Contractor scope changes. A quick and collaborative approach to changing field conditions when they occur is critical to keeping projects on schedule and on budget.
And when construction is close to achieving substantial completion, the SE should have one last opportunity to visit the jobsite. Major structural work has likely been done for months. And while much of the building may be covered up at this time, this last visit provides one last look at the building for the design professional to confirm what was designed is what was built. Has anything changed since the last visit? Did any modifications happen in the field that were not communicated to the SE? Often everything is coming together as designed, but this is the last opportunity to confirm before the building goes into use.
And finally, developing a final as-built set that incorporates any updates during construction should be a part of every project. The as-built set allows Owners a snapshot of the actual construction of the building and a tool to rely on for future improvements to the building.
It should go without saying how important the Structural Engineer’s role is in construction and how important the construction period is for the Structural Engineer. The Nishkian firms nearly 100 years of Structural Engineering service includes significant achievements that could not have been realized without their critical involvement during construction. It’s an important part of the process we go through each and every time.
Wood is often seen in multi-family mid-rise buildings as the most economical construction material. While the purpose of joists, beams, and wood stud walls are easily understood in their role carrying the gravity loads of a building, the lateral load resisting elements and how they work can be more confusing.
Lateral Load Resisting Shear Walls
When lateral loads due to wind forces or a seismic event hit a building, the loads travel through the floor, collecting into and being resisted by wood shear walls. The top and bottom plates of the shear walls act as continuous collectors, moving the lateral loads from the diaphragm into the shear wall. Plywood sheathing, the nailing of the plywood to wood studs, and anchor bolts at the sill plate resist the shear forces. As the lateral loads move from a horizontal plane (i.e. the floor) to a vertical plane (i.e. the wall), the lateral loads also create vertical tension and compression forces, which are resisted by end posts and a hold-down system located at each end of the shear wall.
Figure 1: Components of a Shear Wall
At the beginning of a project, as unit layouts and floor plans are being set, it is important to ensure that the building will have an appropriate shear wall layout. In multi-family buildings, corridors usually afford a sufficient length of interior shear walls, but exterior shear walls must be carefully coordinated between the client, architect, and structural engineer. Façade features, window sizes, and window locations can all critically affect exterior shear wall designs.
Stacking Shear Walls
Structurally, it is always more efficient to stack shear walls from the top of the building to the foundation (or podium). This allows the components that resist the compressive and uplift forces to be continuous. When shear walls do not stack, the building code requires that components be designed for an increased load, and extra framing members and connections are required to transfer the loads.
Figure 2: Stacked Shear Walls
The shear wall design is not just determined by the number of shear walls, but also the length of each shear wall. As shear walls get shorter, the hold-down system gets loaded more heavily. The minimum length of shear wall permitted on a project depends on the floor-to-floor height – the taller a floor, the longer a shear wall must be. This aspect ratio is determined by taking the height (h) and dividing it by the shear wall length (bs). Shear walls cannot have an aspect ratio greater than 3.5 but as a rule of thumb, aspect ratios should be less than 2. Where the aspect ratio exceeds 2, the wall’s shear capacity is penalized. In other words, shear wall lengths should always aim to be greater than half the floor height.
Nishkian Chamberlain has extensive experience with multi-family construction and would be happy to help you find cost-effective solutions to your construction and development needs. Please do not hesitate to contact us at NCInfo@Nishkian.com, or give us a call at (310) 853-7180. You can also go to our Contact page to connect with any one of our offices in your region.
Figure 3: Aspect Ratio
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.
We are currently performing dozens of these evaluations on projects throughout California, efficiently utilizing the ASCE standard ASCE/SEI 41-13. Copyrighted in 2014 by the American Society of Civil Engineers, the standard was developed and written to combine the previously adopted standards ASCE 31 and 41 into a single document for the Seismic Evaluation and Retrofit of Existing Buildings. Whereas past retrofit designs often did not align with evaluations due to having documents with differing criteria for evaluations versus design, this single document coalesces both evaluation and design of existing building retrofits providing one coordinated methodology. Seismic evaluation is defined as an approved process or methodology of evaluating deficiencies in a building that prevent the building from achieving a selected Performance Objective. Seismic retrofit is defined as the measures taken to improve the seismic performance of a building by the correction of deficiencies identified in the evaluation relative to a selected Performance Objective.
The initial step in the process is to assist the client in establishing or selecting a Performance Objective which is a combination of a desired Structural and Non-Structural Performance Levels paired with Seismic Hazard Level(s). The chart below demonstrates the different Performance Level terminology:
Following the establishment of a Performance Level, the Seismic Hazard is established based on the seismicity at the building site determined by historical data, with consideration of proximity to known faults and their activity as well as the specified Seismic Hazard Level(s).
Evaluation procedures based upon the selected Performance Objective, level of seismicity and building type are identified in the following flowchart:
Each Tier of evaluation becomes more detailed and complex. The Tier 1, Screening Procedure, is a quick checklist of structural and non-structural components of the building. A Tier 2, Deficiency-Based Evaluation procedure, utilizes more involved checks of the building to provide a deeper understanding of the building’s design. A Tier 3, Systematic Evaluation Procedure, provides a full building review including linear and non-linear / performance based analysis and design options.
The final step in the review process is to prepare an evaluation report to communicate the results of the evaluation to the owner, local jurisdiction or agency requesting the evaluation. Depending upon the availability of information and the scope of the evaluation, the extent of the report may range from a letter to a detailed document.
If the seismic evaluation suggests that a seismic retrofit is warranted, the next step is to perform the design for the retrofit. A Seismic Retrofit design will utilize the evaluation report to identify the seismic deficiencies relative to the selected Performance Objective. One or more of the following strategies to retrofit the deficiencies may be considered:
Nishkian Chamberlain has extensive experience in seismic retrofit projects and is currently working with building owners to assist in identifying the impact that retrofitting in accordance with the City Ordinances will have on their building assets. We are currently working as part of an advisory council to evaluate over 50 buildings for one client that is proactively looking to understand the overall vulnerability of their portfolio.
Should you need the assistance of a trusted advisor to guide you through the uncertainty of the City Ordinances, evaluate an existing building or make additions/modifications to an existing building, contact us at NCInfo@Nishkian.com or give us a call at 310.853.7180 for cost effective, creative seismic retrofit solutions. You can also go to our Contact page to connect with any one of our offices in your region.
By Rachel Wong, S.E., CAPM®
With the January 1st implementation of 2016 California Building Code (CBC), there is a new Building Code in town. Much of the 2016 CBC is similar to the previous 2013 CBC with respect to Structural Engineering with minor updates scattered throughout. However, one of the more significant updates was in regards to existing buildings. The 2015 International Existing Building Code® (IEBC) was adopted with the 2016 CBC as the latest and greatest guideline for existing building repair and modifications.
Originally drafted in 2003, the IEBC has been in the International Code Council (ICC) family of codes for over a decade, but faced limited adoption due to the presence of IBC/CBC Chapter 34 for existing buildings. Previously, IBC/CBC Chapter 34 was responsible for minimum requirements in existing building modifications, but had limited content for the variety of projects it covered. In 2014, the code committee decided that Chapter 34 should be eliminated in favor of the more fully-depicted IEBC. The IEBC maintains much of the prior CBC information, while expanding and clarifying specific topics. For example, a path for compliance of relocated buildings is provided in IEBC, and was previously considered to be a design “grey area”. Within IEBC Appendix A, a series of subsections are now provided for masonry, wood, concrete, and steel design, which previously were beyond the scope of Chapter 34.
But a lot of familiar requirements are present in IEBC, too. Previous CBC Sections 3402 to 3411 can now be found incorporated into the contents of IEBC Chapter 4, and Section 3412 has been relocated to IEBC Chapter 14. The CBC retrofit/strengthening threshold of 5% gravity/10% seismic modifications to existing elements without requiring strengthening to these elements is still applicable for Level 2 alterations that impact less than 50% of the building area.
The IEBC provides options for either prescriptive compliance of a structure or performance-based compliance, and permits the use of alternate methods as well. One of the seismic retrofit documents that go hand-in hand with these provisions is the relatively new ASCE 41-13 document, which will be featured in our upcoming May article.
Viscous Damper Brace Frames in an existing Steel Building
(Performance-Based Compliance Upgrade)
Each of the Nishkian offices has extensive experience with providing cost-effective solutions in retrofit, alteration and additions to existing structures. Should you need assistance with understanding how the new code will affect your existing building project, do not hesitate to contact one of our offices to receive expert assistance with any questions you may have. We are here to help!
The demand for affordable housing in urban areas is increasing as rent prices skyrocket. Many developers are now required to include a percentage of affordable housing units to obtain approvals for their new multi-family construction projects. Additionally, affordable housing projects that wish to access alternate funding sources are often required to meet various green building requirements.
Recently, Nishkian Chamberlain began work on a new affordable housing project in Ventura, California. The project is unique in that it is entirely comprised of affordable housing apartment units. In order to receive some state and federal funding, the project is required to meet several green building targets. One such target is the use of “Advanced Framing”.
In short, Advanced Framing is energy and material-efficient wood framing. Conventional wood framing, typically used for many years, includes many structural redundancies (double top plates, three-stud corners, multiple jack studs, double or triple headers, etc.). The goal of Advanced Framing is to eliminate unnecessary redundancies and achieve savings in material usage while also taking advantage of opportunities for increased energy efficiency.
There are various techniques commonly used in Advanced Framing. Which technique(s) are used is determined on a project-to-project basis. One technique applied to a recent project was the use of engineered wood floor joists. Using engineered wood floor joists allowed larger joists spans and wider joist spacing, leading to savings in materials, increased construction efficiency, and reduced construction costs. It is critical for the structural engineer on the project to coordinate joist depths, which may be larger due to the increased spans and spacing, with the architect and MEP early on in the project to minimize conflicts and rework later on.
Additionally, for this project, the increased floor joist spacing affected the design of the floor sheathing. A larger span rating was required, and serviceability characteristics such as floor vibration were investigated. It was recommended to use a thicker floor sheathing than what we use for Conventional Framing to achieve the required span rating, reduce vibrations and increase the perceived stiffness of the floor.
In addition to using engineered wood floor joists, other Advanced Framing techniques include:
These techniques can be mixed and matched to accommodate the unique aspects of each project while still achieving the targeted green building requirements.
In conclusion, the demand for affordable housing is increasing, especially in high density urban areas where housing is in short supply and rents are high. Affordable housing projects often target green building requirements such as the use of Advanced Framing techniques to obtain State and Federal funding. Advanced Framing techniques can be used individually or in combination to achieve the desired green building criteria.
If you are interested in finding out how using Advanced Framing techniques can benefit your next project, Nishkian Chamberlain has significant experience in this technique and would be happy to discuss your construction and development needs. You may contact Craig Chamberlain at CChamberlain@nishkian.com or (310) 853-7180.
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.
Of the roughly 2,040 buildings, about 1,700 of them are suspected to be wooden apartment buildings with carports on the ground floor, known as soft-story buildings, one such complex collapsed in the 1994 Northridge earthquake, killing 16 people on the ground floor in the predawn darkness.
About 200 are suspected vulnerable brick buildings, also known as unreinforced masonry, in which bricks can come spilling out of walls, striking occupants and passersby and triggering the collapse of the roof. 60 suspected brittle concrete buildings were listed, holding residences, hotel rooms and office space. 30 Concrete Tilt-up buildings susceptible to failure at interconnection between the roof and the wall could cause the wall to pull away from the building resulting collapse of the roof. And finally, 80 steel moment-frame buildings, with the tallest a 13-story condominium and two 12-story office buildings, that could be vulnerable in an earthquake.
Santa Monica’s proposed law gives owners of steel buildings the most time to retrofit once an order is given to evaluate the structure — 20 years. Brittle concrete buildings will have a deadline of 10 years; wooden apartment buildings, six years; tilt-ups, three years; and brick buildings, two years.
Other Southern California cities are also looking to strengthen their seismic safety laws. West Hollywood and Beverly Hills are both considering mandatory retrofit laws, and elected leaders are now casting the issue as not one of cost, but of public safety. Stricter retrofit ordinances are also becoming law up and down the west coast.
Nishkian Chamberlain has extensive experience in seismic retrofit projects and is currently working with building owners to assist in identifying the impact that retrofitting in accordance with the City Ordinances will have on their building assets. We are currently working as part of an advisory council to evaluate 50 of 200 buildings for one client that is proactively looking to understand the vulnerability of their portfolio.
Should you need the assistance of a trusted advisor to guide you through the uncertainty of the City Ordinances and provide cost effective, creative seismic retrofit solutions, contact Craig Chamberlain at CChamberlain@nishkian.com. You can also go to our website at www.nishkian.com to connect with any one of our offices in your region.
Our Los Angeles area office is happy to announce we’re growing to serve the needs of our community. Please join us in welcoming five new additions to the Nishkian Chamberlain team– Jason Gray, Kiki Okaly, Ivan Canete, Bethany MacDuff and David Brisco.
In our dedicated effort to provide top quality service to our clients and the community we serve, we are continuously looking for talented people to join our team of professional consulting and structural engineers. If you or someone you know is interested in learning more about the opportunities to advance your career, please feel free to email Craig Chamberlain, Managing Principal of Nishkian Chamberlain at email@example.com.
The Academy Square project is a new $300 million mixed used project being developed by Kilroy Realty Corp. and is located in the heart of Hollywood. The project has a 150,000+ square-foot footprint, the size of an entire city block, and over one million square-feet of office space. It is being designed with House & Robertson Architects, Inc. serving as the Executive Architect for the commercial portion, GBD Architects serving as the architect for the residential portion and Shimoda Design Group serving as the design and landscape architect.
With project architect CSDA Design Group, Nishkian Chamberlain is working on two replacement buildings for the Olive Vista Middle School campus within the Los Angeles Unified School District (LAUSD). Originally designated for evaluation in accordance with AB 300 – a bill passed in 1999 to assess K thru 12 school buildings for seismic safety – the gymnasium and multi-purpose buildings were eventually determined to be replaced. Nishkian Chamberlain assisted with a seismic study and full site analysis of both structures in order to obtain Proposition 1D funding to provide a cost benefit for replacement of the two buildings.
Construction on the 250-unit luxury apartment building project at the 580 Anton site began in the spring of 2016 and has been steadily progressing all summer long.
Nishkian Chamberlain has recently been involved in a number of exciting education projects throughout the Southern California area. The projects below highlight the variety of work being done by Nishkian Chamberlain in this market sector.
Originally designed in 1968 by celebrated Los Angeles based modernist architect Craig Ellwood, 777 Aviation is now being renovated into a 309,000 square foot glass and steel building in the heart of El Segundo’s new creative office hub. Skidmore, Owings & Merrill LLP (SOM) led the design as the architect, with Nishkian Chamberlain as the structural engineer and WL Butler as the general contractor. Joint venture partners Embarcadero Capital Partners and Westbrook Partners have already signed a lease with the U.S. General Services Administration for 154,000 square feet – just under half the building footprint.
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.
We plan a quarterly out-of-the-office opportunity for our hard working team of Engineers, Draftspersons and Administrative staff to enjoy time together beyond just crunching numbers. While some of the other reasons might come to mind first, encouraging departmental integration is essential in today’s business world and out-of-the-office events help integrate our team. Simple conversations help respect various people’s responsibilities and roles within our organization.
Sheraton San Gabriel is located in the heart of historic San Gabriel, home to roughly 40,000 people, and within a short drive of multiple attractions, including Santa Anita Race Track, the Rose Bowl Stadium, Dodger Stadium, Staples Center, Disneyland, and Knott’s Berry Farm. The hotel will also be steps away from the San Gabriel Square Mall, which has been dubbed the “Great Mall of China,” housing Chinese specialty shops within its 220,000 square feet of retail space.
The Orange County Fairground is host to many events each year and one of the biggest venues there is the Pacific Amphitheater. Nishkian Chamberlain is proud to be part of the design team that was tasked to bring a new entrance structure and entryway plaza to the venue.
The 2015 economy and projected construction projects has resulted in an incredibly strong start in 2016 for Nishkian Chamberlain! As our company portfolio grows so does our need to find good quality talented team members.
Nishkian Chamberlain has been an active participant in the SEAOSC job fair, typically held the first week of February, which is an opportunity to provide funding for scholarships for those students who are pursuing structural engineering majors in college. The SEAOSC event also gives students the chance to talk with industry professionals and to make introductions for future internships and job placement opportunities. This year’s turnout was a tremendous success with over 35 prospective team members stopping by our booth to discuss their future.
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.
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 accomplished professionals in a highly specialized field it is easy to forget the hard work and effort required along the path to our careers. For many of us, our careers are not an accomplishment that could be achieved without guidance from more experienced individuals. In recognition of the importance the role of mentors have played in achieving success, several engineers in the Nishkian Chamberlain office are involved in a variety of youth mentoring programs. Our roles in the programs vary, but the prevailing theme is to enlighten, motivate, and encourage students to find happiness in excelling academically, socially, and professionally.
The design has been worked on for months, perhaps years. The engineers have completed their extensive analysis on the structure. The drawings have reached 100% CD’s. The building department has completed their review and is now ready to issue a permit for construction. The SE’s role is done, right? On to the next project!
In reality, only design work is essentially complete while the enormous task of actually constructing the project is just beginning. The Structural Engineer plays a vital part to the successful completion of a project through construction and their involvement during construction with the Owner, Architect, other design consultants, and contractor is critical.
A Structural Engineer provides a key link for the Contractor during construction, but the SE’s role and connection with construction of the project starts well before the first shovel hits dirt. Coordination of a well-planned and detailed set of construction documents is a critical first step. Unforeseen site conditions are costly enough, however, without this first step, a project can get lost in request for information (RFI’s) or confusing drawings. A well-coordinated set of documents includes coordination among the many design disciplines. This involves checks between different consultant drawings and collaboration of design team members during meetings to resolve challenges during design and before construction.
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.
Whether it’s for work or pleasure, Hospitality building projects need to accommodate a myriad of different travelers.
The Nishkian Chamberlain team is currently working on a numerous Hospitality projects of which we highlight two this blog. One project, pending permits from the building department, is the Courtyard by Marriott project in Santa Cruz, California conveniently located less than a quarter-mile from the beach and will provide over 160,000 sq. ft. of comfort and convenience for vacationing families, busy businessmen, and fun-loving jetsetters. Another project is the construction of a new swimming pool and bar area at the Terranea Resort, located on the Palos Verdes Peninsula in Southern California.
Planned tenant improvements (TI) and a review of building code requirements were discussed in a previous blog post, but… what happens when structural requirements of a new tenant space may need considerations different from what the “Building Code” specifies for strength and stiffness? We commonly experience specific client parameters beyond what the Building Code addresses for our fitness club clients who are commonly moving into new mixed-use spaces below residences or into repurposed, previously designed, office space. While there are alterations that we often think of as standard structural tenant improvement modifications, such as new openings for staircases, or new MEP units for ventilation, some of the upgrades to the existing structure require investigation beyond typical Building Code issues.
Owners of new and existing mixed-use buildings typically have two main concerns when considering leasing space to a new fitness club tenant, the transmission of noise and vibration into sensitive adjacent tenant areas. The comfort of office and residential tenants, which typically share tenancy in the mixed–use building development, is a great concern. Careful measures and criterion must be developed to mitigate that the noise and vibrations from the fitness club tenant from propagating into more sensitive areas of the structure and disturbing the other building tenants. In collaboration with an acoustic/vibration consultant, recommendations for the comfort level of all the building tenants will typically determine what treatments need to be made, but the structure itself must be prepared to receive the treatment.
Koreatown, a neighborhood in Central Los Angeles centered near Eighth Street and Western Avenue, is the most densely populated and diverse district by population in Los Angeles County, with some 120,000 residents in 2.7 square miles. The neighborhood lies near mass transit hubs including the Red Line and new Purple Line, 3 miles west of downtown Los Angeles, 4 miles south-east of Hollywood, 12 miles from Santa Monica Beach and 16 miles from Los Angeles International Airport. The boundary for Koreatown is approximately from Beverly Boulevard to the north to Olympic Boulevard to the south and S. Wilton Place from the west to S. Virgil Avenue to the east. And development is booming!
The surrounding areas are also actively growing; there is a resurgence of activity in residential, retail, and office in Downtown LA, the Westside is as strong as ever, and Miracle Mile is realizing huge growth in entertainment clients. Koreatown is the hub of all of these areas and begs new development as urbanization moves people from the suburbs closer to where they actually work. The population is looking to cut down their commuting time and carbon footprint and live somewhere with more infrastructure and amenities.
The SCU Arts and Art History building is a new three story structure with classrooms and studios for faculty and staff at Santa Clara University located in Santa Clara, California. The architectural design was completed by Form4 Architecture Inc. The structure is a traditional steel framed building with buckling restrained braced frames serving as the lateral force resisting system. Notable features include the domed/mansard roof clad in Spanish tile and a custom designed Chihuly sculpture hung over the entrance lobby. The SCU Arts building is one of a several projects where we serve as the structural consultants for Santa Clara University.
Construction on the project has recently begun with Devcon Inc. serving as the contractor. The preconstruction phase began in December 2014 with an emphasis on reducing construction costs with value engineering and coordinating subtle detailing items between architect, contractor, and structural engineering disciplines.
Building owners and architectural consultants lose many a night’s sleep wondering how much they can alter the existing building space and structure to accommodate and attract new tenants before they are slammed with the Department of Building and Safety’s request to have the “Existing Structure Reviewed or Upgraded.” In a previous blog post, a review of the requirements for upgrading existing structures was discussed with a focus on repair due to unexpected building damage. In this post we focus on planned tenant improvements, a quick review of Code requirements, and a short project example.
Tenant improvements (TI’s) are one of the most common projects in construction today. Often renovations, upgrades, or even additions to existing structures are more enticing for Owners than building from the ground up. With limited budgets and tight timelines, sometimes tenant improvements are the only answer for “new” space. TI’s can work within tight budgets by reusing much of the existing structure or at a minimum within the framework of the original building. They also save time by eliminating some of the overall building construction as well as simplifying the permitting process with fewer permits not to mention fewer fees to be paid.
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:
The Nishkian Chamberlain group of Consulting and Structural Engineers are currently collaborating with developers and architects on several new Multi-Family and Mixed-Use development projects. Here is a sample of a few projects we are currently working on:
Bryant Street Development in San Francisco, CA
The Bryant Street development, currently under design, is a collaboration with the owner, Nick Podell Company and the architect, BDE Architecture. The development consists of razing the majority of an entire Mission District block and constructing nearly 300,000 square feet of Mixed-Use development. The new building consists of a six-stories with two distinct architectural styles, 274 apartments, 4,300 square foot ground floor retail space and underground parking for 160 cars and 145 bikes all fronting Bryant, 18th, and Florida Streets. Special structural considerations include: a creative analysis approach of the structures lateral force resisting system to reduce the cost of construction by eliminating the need for exterior shearwalls; a post–tensioned concrete podium first floor slab – supporting first floor park- like landscaped setting with large trees and planted areas; a “Mat Foundation” system to eliminate the use of extremely large spread footings and minimize differential settlement due to varied soil conditions across the site; the design of an accessible roof top dining lounge area, BBQs, large wood arbors and trellises, and planting areas. The project is currently in design with construction slated to begin in 2015.
Almost everywhere we look, it seems an older, outdated shopping mall is undergoing a substantial commercial construction renovation. In the Los Angeles area alone, there are probably close to a dozen local and regional shopping malls in the middle of a shopping center renovation project, or slated to begin one in the very near future.
Del Amo Fashion Center located in Torrance, California is in the midst of a major redevelopment which includes the construction of brand new Patio Cafes in the heart of the shopping center, near the central Macy’s store.
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.
Nishkian Chamberlain, Inc. is pleased to announce that we are expanding. It’s only been a year since we’ve moved into our office in Culver City. With the addition of new engineers and our busy work load, we are breaking through walls and adding needed floor space. Come by and take a look as we add new furniture and staff. We are located conveniently just off the 10 Freeway on Robertson Boulevard and just east of downtown Culver City.
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.
Nishkian Chamberlain is proud to be working with Kollin Altomare Architects on a new mixed-use development along the Valley Boulevard Corridor in San Gabriel, California.
Public education in the State of California consists of two systems. One system provides education from kindergarten through grade 12 (K-12) with current enrollment of approximately 6.3 million students. The other system, commonly referred to as “higher education” includes California Community Colleges, California State Universities and the University of California with enrollment of approximately, 2.1 million students. Many of these schools have buildings that were built up to 80 years ago which are still in service and badly in need of modernization and/or repair. Over the years, Nishkian firms have been involved in both new and retrofit construction of California schools throughout the state as well as across the West coast.
With more than 60 locations in the United States, Equinox Fitness Clubs are creating an integrated approach to the well-balanced life – from personal training to group fitness to rejuvenating wellness treatments in major metropolitan locations. Nishkian Chamberlain has engineered a large number of these locations in the Southern California area and across the country.
The most important asset in the community and for our future is our children. Every parent has a natural apprehension when sending their children off to school each morning. Worrying about their safety in the classroom should not be one those concerns.
The 1933 Long Beach Earthquake was the turning point for seismic design and construction oversight for California public schools. The early evening earthquake in which 120 lives were lost and many school buildings suffered significant damage clearly demonstrated the need for more to be done for our children’s safety in their school buildings. Had the earthquake occurred during school hours it’s thought the fatalities would have been significantly higher! Out of the earthquake though, the California State Legislature passed the Field Act to prevent such scenarios from happening in our schools and provide a framework for designing and constructing better school buildings.
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.
In 2005, an amendment to the Los Angles Municipal code called “Small Lot Subdivision” was passed. This amendment provides new options for the housing market in LA County. Individuals or developers can now subdivide commercial or multi-family zoned lots into much smaller lots. The previous minimum size for a single family lot was 5,000 square feet, but now has been reduced to just 600 sq.ft. with a minimum width of 16 feet These smaller lots have little to no setback requirements and are fee-simple parcels. Unlike condo owners, resident of the small-lot homes own a plot of land and a home that is built on a separate foundation. These homes rarely have adjoining walls and are usually just inches apart from their neighbor. There is no Home Owners Associations or HOA fees with these subdivisions with only a small fee for maintenance of the common areas. The money saving benefits are for both the developer and the homeowner with each unit sold. There is less liability and insurance costs for the developer in building single and multi-family units versus condos while the homeowner can afford small-lot homes in prime locations where the costs have continued to skyrocket in recent years. Each project can triple the density of an existing parcel while maintaining design and functionality of the area. Guidelines have been established for roof lines, parking, driveway spacing, circulation walkways and primary entryways.
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.
Culver City, CA – Nishkian Chamberlain relocated their Los Angeles based office to Culver City earlier this year. Our new office is centrally located within the greater Los Angeles area to better serve our clients throughout the region. With nearly 3, 000 square feet, the office allows us room for our growing business and provides a fresh new space. The creative office is based on an open plan layout to foster collaboration among staff who work closely together on each and every project. Our conference room can seat a dozen or more and is frequently used for staff, client and project team meetings.
Nishkian Chamberlain, Inc. congratulates Andaz Hotels for winning the Partnership Award at the 2013 LE Miami Awards brought to you by Travel + Leisure and DEPARTURES. The LE Miami Awards were designed to discover the edgiest and most creative pioneers in contemporary travel. The multi-year collaboration with Women for Women International (WfWI), a non-profit organization that helps female survivors of war move from crisis and poverty to stability and self-sufficiency, is integrated across Andaz hotels globally. It provides skills training and income opportunities for women in Iraq participating in the WfWI graduate program, teaching sewing and silk screening to produce laundry bags at a fair wage. Each hotel also sponsors the WfWI Life-Skills Training Program, which supplies school fees, access to food and water and start-up funds for women to open their own businesses.
Agoura Hills, CA – Construction on the new Agoura Hills Recreation Center near the civic center and library on Ladyface Court will begin this month, officials say. Nishkian Chamberlain, Inc. teams up with Roesling Nakamura Terada Architects in Ventura to design and build the center that will feature the conversion of approximately 16,000 square feet of existing building space as well as construction of several new structures and additions to existing structures totaling an additional 9,000 square feet. The new space will house events and meetings in addition to a warming kitchen, restrooms and storage. Altogether, the center will span over 25,000 square feet on the 6-acre site and will accommodate a variety of recreational services for all ages. The construction of the new center will take from nine to 12 months to complete.
For the full article and the link to architectural renderings, visit http://www.ci.agoura-hills.ca.us/government/departments/community-services-parks-recreation/new-home-for-the-agoura-hills-recreation-center