Fischer E.C.,Degenkolb Engineers |
Selden K.L.,Elstner Inc. |
Varma A.H.,Purdue University
Journal of Structural Engineering (United States) | Year: 2017
This paper summarizes the results of experimental investigations on steel composite beams with simple connections at elevated temperatures. In the United States, three different types of simple connections are most commonly used in building construction with steel composite beams: (1) double-angle connections; (2) single-angle connections; and (3) shear-tab connections. A testing program was conducted to examine the structural behavior of all three of these connections at elevated temperatures. Each specimen consisted of a steel composite beam attached to a loading frame with simple connections. The specimens were subjected to controlled heating and cooling curves while the loading frames were fire protected and designed to remain in the elastic range. The shear-tab connections showed the largest connection rotation, but they fractured during the cooling phase of the tests. The prying of the angles in the double-angle and single-angle connection during the tests provided ductility to prevent fracture during the cooling phase of the experiments. The double-angle connections demonstrated the least connection rotation and excellent performance during the tests. © 2016 American Society of Civil Engineers.
Wang S.,University of California |
Lai J.-W.,Degenkolb Engineers |
Schoettler M.J.,University of California at Berkeley |
Mahin S.A.,University of California |
Mahin S.A.,University of California at Berkeley
Engineering Structures | Year: 2017
The Tall Buildings Initiative (TBI) program of Pacific Earthquake Engineering Research Center has been expanded to consider the seismic performance of existing tall buildings. This paper selects a 35-story steel moment resisting frame (SMRF), designed in 1968 with construction details representative of that period, for detailed seismic evaluation in the framework of Performance Based Earthquake Engineering (PBEE). A three-dimensional numerical model capturing the mechanical properties of the most critical structural elements was generated using the program: Open System for Earthquake Engineering Simulation (OpenSees). Systematic nonlinear response history analysis (NRHA) under two basic safety earthquake (BSE) hazard levels for existing buildings were performed following ASCE 41-13 guideline. Probabilistic checks on the confidence levels of the building to achieve collapse prevention (CP) and immediate occupancy (IO) at different hazard levels were conducted based on FEMA 351. In addition, damage and loss analysis was carried out using FEMA P-58 PBEE methodology. Analysis results following different procedures all predicted that the case-study building failed to meet the recommended performance objectives and had a variety of seismic vulnerabilities, and possible retrofits were needed. © 2017 Elsevier Ltd
News Article | December 6, 2016
Sprig Electric, one of the largest electrical contractors in the Bay Area, announced today that its San Francisco office has recently completed the electrical infrastructure for Transbay Block 6, and has been awarded a contract to build the electrical infrastructure at 505 Brannan in San Francisco. Transbay Block 6 is a 32-story, 409-unit luxury high-rise complex in San Francisco’s South of Market (SoMa) District. The complex, located at 299 Fremont Street, includes an apartment tower, townhome residences, a ground-level courtyard and street-front retail, all 3 blocks from the Transbay Transit Center. The San Francisco office of Solomon Cordwell Buenz (SCB) designed the apartment community, and will serve as the architect of record; the general contractor is a joint venture between Balfour Beatty and Cahill Contractors LLC. The 7-story building at 505 Brannan will become the home of Pinterest. The architect is Heller Manus and the General Contractor is Swinerton Builders. Sprig Electric will provide electrical services and low voltage infrastructure for the 150,000-sq.-ft. facility, as well as install the security system. Completion is scheduled for the fall of 2017. Sprig Electric has also been awarded a contract to complete electrical services for 500 Folsom, a 42-story apartment high-rise known as Transbay Block 9. Executive Vice President Rick Clinton said Sprig Electric’s San Francisco office opened in 2010 with 4 employees, and has since expanded to 25 office staff and over 100 electricians in the field. “We are proud of the growth that Sprig Electric has experienced in San Francisco, and recently celebrated our 6th anniversary at our 65 Oak Grove Street location,” he said. “San Francisco’s expansion in both the tech sectors and the multi-family housing market has helped to fuel our growth.” Sprig Electric also announced it has recently completed tenant improvements for several other San Francisco projects, including two facilities that are headquartered within the new Metropolitan Transportation Commission (MTC) Bay Area Headquarters Authority (BAHA) at 375 Beale Street. These include a 30,000-sq.-ft. buildout of a customer service center for Bay Area FasTrak, and a 13,000-sq.-ft. tenant improvement for offices of Rutherford + Chekene, a structural engineering firm. Ongoing projects at 375 Beale Street including a buildout for the ADA Café and retail store; a 90,000-sq.-ft. tenant improvement for Twilio Inc., a technology startup; and a 20,000-sq.-ft. buildout for Degenkolb Engineers. About Sprig Electric Sprig Electric, headquartered in Silicon Valley, is a full-service electrical and data communications contractor that designs and installs electrical, data/communications, and fire alarm systems for a variety of sectors including commercial, residential, educational, life sciences, high-tech, data center, healthcare, institutional, retail, sports, entertainment, hospitality, manufacturing, site development, alternative energy, and energy audit/efficiency. The Sprig Electric Energy Solution Division specializes in the engineering, procurement, and construction (EPC) of solar photovoltaic (PV) systems. Services include energy audits/efficiency, along with installation of solar photovoltaic and battery storage systems. Sprig Electric has offices in San Francisco, San Jose and Livermore. For more information, visit Sprig Electric’s website at http://www.sprigelectric.com. The Sprig Electric San Francisco office is located at 65 Oak Grove Street and can be reached by phone at 415.536.7848
News Article | December 8, 2016
The Pacific Northwest is due for a catastrophic earthquake. When it happens, the region will almost certainly face a tsunami for which it is utterly unprepared. Westport, Washington, is among the few places taking steps to prepare for such a disaster, which seismologists give a one-in-three chance of happening in the next 50 years. The coastal community, working with TCF Architecture and Degenkolb Engineers, has designed and built an elementary school gymnasium that can withstand the forces of an earthquake and tsunami, while protecting upwards of 1,000 students and community members. And while the building is built like a bunker, it doesn’t look like one. “We tried to employ anything we could to make it more relatable to an elementary school student who is four feet tall,” says Brian Ho, principal at TCF Architecture. That’s no mean feat for a structure surrounded by steel columns, clad in concrete masonry and metal walls, topped by a six-inch-thick steel-and-concrete roof, and anchored by concrete piles that extend 55-feet into the sandy earth. These fortifications helped the Ocosta Elementary School gymnasium meet guidelines from FEMA, and forthcoming codes from the American Society of Civil Engineers, for what evacuation specialists call vertical evacuation shelters. Unlike horizontal evacuation methods (think roads and bridges), which provide people a means of escape from an area threatened by a natural disaster, vertical evacuations shelters are designed to provide shelter to people caught in a disaster’s path. According to TCF, the school is the first vertical shelter in North America. By modeling natural disaster scenarios that could specifically affect the Ocosta area, researchers at the University of Washington have determined that the gym’s roof, which rises 53 feet above sea level, could shelter 1,000 people in the event of a massive earthquake and tsunami. All that steel and concrete is perfect for a tsunami shelter, but overkill for a school gymnasium. To temper the building’s burly form, the architects at TCF topped the structure with a peaked roof, a rustic architectural element common in the region. They covered the building in small windows and doors (also cribbed from the local architectural vernacular), to break its monolithic form into more manageable visual chunks. They colored the metal siding with tones drawn from the local landscape. Inside, graphics, photos, and materials reflect the area’s agricultural, maritime, and logging-related histories, while bright, colorful spaces make the interior more approachable for little users. The entire project included the gym and a new school building attached to a wing of existing classrooms. Other evacuation solutions are in the works throughout the region. Ocosta’s gym was spurred in part by Project Safe Haven, a planning effort launched by local and federal government agencies to identify possible tsunami shelter areas up and down the Washington coast. The city of Long Beach, Washington is planning a FEMA-funded, one-square-acre, 34-foot-tall berm of hard-packed earth that would provide high ground for about 800 people during a tsunami. Voters in Seaside, Washington, recently approved a plan to move three schools to higher ground, out of tsunami range. And one architect has built a house on nearby Camano Island that he claims is tsunami-proof. But efforts to earthquake- and tsunami-proof the coasts of both Washington and Oregon have been slow to advance, largely because of cost. “A lot of the communities along the coast, they’re not rolling in money. And these are expensive structures,” says Meg Olson, who worked at Project Safe Haven until 2013. (She says many people also doubt that the shelters would work, in a disaster scenario.) Voters rejected the bond to pay for the Ocosta school two times before they approved it. Officials also applied for FEMA funds for the school, but didn’t get them. “We have these natural disasters that the public is aware of that do get funded,” Ho says. “We haven’t seen a tsunami in this country in 300 years. That may speak a little to why nothing has happened.” Hopefully that will change. At $16 million (about three-quarters of which was construction cost), Degenkolb engineer Kale Ash says the Ocosta Elementary project cost about ten percent more than a non fortified school. “That’s a pretty small premium to pay for savings the lives of hundreds of people.” You’d think so. Hopefully it won’t take a devastating tsunami to change people’s minds.
Miller D.J.,Degenkolb Engineers |
Fahnestock L.A.,University of Illinois at Urbana - Champaign |
Eatherton M.R.,Virginia Polytechnic Institute and State University
Engineering Structures | Year: 2012
Buildings designed with conventional ductile earthquake-resisting structural systems are expected to provide life safety performance, but they rely on significant structural damage to dissipate the seismic energy. This structural damage and the residual drift that may result from the inelastic response can make a building difficult, if not financially unreasonable, to repair after an earthquake. As a result, development of systems that dissipate energy, minimize structural damage, and return to their initial position (" self-center" ) following an earthquake is needed. This paper presents a viable solution including experimental investigation of the cyclic behavior and performance of a self-centering buckling-restrained brace (SC-BRB). A SC-BRB consists of a typical BRB component, which provides energy dissipation, and pre-tensioned superelastic nickel-titanium (NiTi) shape memory alloy (SMA) rods, which provide self-centering and additional energy dissipation. The SMA rods are attached to the BRB portion of the brace using a set of concentric tubes and free-floating end plates that cause the SMA rods to elongate when the brace is in both tension and compression. Large-scale SC-BRBs were designed, fabricated and tested using a cyclic protocol to validate the brace concept. The experimental program demonstrated that NiTi SMA SC-BRBs provide stable hysteretic response with appreciable energy dissipation, self-centering ability, and large maximum and cumulative deformation capacities. © 2012 Elsevier Ltd.
Nacamuli M.,Degenkolb Engineers
Structures Congress 2012 - Proceedings of the 2012 Structures Congress | Year: 2012
Base isolation of mission critical data center equipment provides high performance seismic protection of sensitive systems in seismically active regions. Base isolation technology works by decoupling the isolated elements from the horizontal component of strong ground motion shaking, essentially allowing the ground to move underneath the component without transmitting the damaging ground accelerations above the plane of isolation. The accelerations imposed on base isolated equipment can be five or more times lower when compared with a traditional fixed-base anchorage system, depending on location. This significantly improves the probability that the data center can continue to function following a seismic event. Base isolation has been in use since the 1970s to protect buildings and other large structures from earthquake shaking in seismically active areas around the world. WorkSafe Technologies owns the patents on Ball-N-Cone isolation technology, which uses two steel dishes and ball bearing to provide seismic isolation and has developed systems for isolating individual cabinets as well as an entire access floor. The Ball-N-Cone isolators are well suited to the lighter vertical loads associated with data center components compared to those present in larger building and bridge structures. The WorkSafe ISO-Base planks are unique in applying isolation technology to individual server cabinets, or rows of cabinets. The Isolated Raised Access Floor applies the same isolation technology, but to an entire access floor by moving the isolation plane to the base of the access floor pedestals. The benefits of using isolation as opposed to conventional bracing are two-fold - critical equipment is protected against damaging earthquake accelerations allowing for operational performance and facility managers do not have to deal with installing traditional bracing, with the associated concrete drilling and relatively heavy construction in the sensitive data center environment. © ASCE 2012.
Comber M.V.,Degenkolb Engineers |
Poland C.,Degenkolb Engineers |
Sinclair M.,Degenkolb Engineers
Structures Congress 2012 - Proceedings of the 2012 Structures Congress | Year: 2012
Recent disasters and organizations such as SPUR have identified and highlighted a need for a shift away from designing code-minimum buildings that are life-safe but often "disposable." An important piece of this shift requires an understanding of buildings' life-cycle costs including a consideration of the associated environmental impacts induced by earthquake damage. Appropriate detailing of nonstructural components, the use of high-performance structural systems that outperform typical code-based designs, and consideration of the interactions between structural and nonstructural systems can greatly reduce expected damage and minimize the environmental impacts associated with seismic damage throughout a building's life. To evaluate seismic force-resisting systems and weigh their relative long term environmental impacts, the expected seismic damage throughout a building's lifespan and the environmental impact associated with that damage must be quantified. A method for performing such an evaluation has been developed by the authors and is discussed. Results of case study projects are presented and compared, along with lessons learned from the case studies and applications. © ASCE 2012.
Restrepo J.I.,University of California at San Diego |
Bersofsky A.M.,Degenkolb Engineers
Thin-Walled Structures | Year: 2011
This paper presents results from quasi-static racking tests on gypsum wallboard sheathed light gage metal stud partition walls used in buildings. Eight nearly identical pairs of specimens were constructed following common United States practice. Each specimen consisted of a 4.88 m long and 2.44 m tall web wall and two return walls each 1.2 m long and 2.44 m tall. The main variables were (i) the configuration of the specimen, (ii) the spacing of wallboard-light gage stud self-tapping screws, (iii) the stud thickness and spacing, (iv) the presence of a vertically slotted track at the top of the partition wall, and (v) the wallboard thickness. © 2010 Elsevier Ltd. All rights reserved.
Ballantyne D.,Degenkolb Engineers
Distribution Systems Symposium and Water Security and Emergency Preparedness Conference and Exposition 2012, DSS 2012 | Year: 2012
Risk assessment methodologies for earthquakes have developed beyond those presented in Appendix G of AWWA J100, Risk and Resilience Management of Water and Wastewater Systems. This paper presents those methodologies, identifies resource documents, and shows project examples that demonstrate some of the opportunities risk analysis can offer. Shaking intensity hazards from earthquakes are quantified for selected scenarios representing a range of probabilities and associated return periods. Analyzing multiple scenarios of different sizes ultimately allows estimation of annualized losses. Liquefaction probability and associated permanent ground deformation (PGD) can also be quantified for each scenario and location considering the shaking intensity and various soil parameters. Fragility curves are developed for each facility or facility component such as tanks and treatment plants. Fragilities relate shaking intensity or PGD versus expected damage. Fragility relationships are based on empirical data, analysis, and/or expert opinion. Fragilities are also developed for buried pipelines considering pipe material and joint design. Shaking and liquefaction hazards are then "related" to each facility, and the expected damage is estimated. The combination of the earthquake scenario probability and the damage probability results in the "probability of occurrence". Once the expected damage is known for each facility, the damage or functionality of the overall system can be determined. This can be accomplished using expert opinion involving operations personnel and engineers familiar with the system, or using analytical system modeling techniques. The result can be presented in terms of probability of being functional for a given earthquake scenario. Outage times can be estimated considering the expected damage and available resources for repair. "Resulting consequences" (losses) can be calculated including: repair costs, cost of providing temporary service, loss of utility income, and community business interruption losses - with all costs annualized by considering multiple scenarios. The combination of "probability of occurrence" times the "resulting consequences" results in a calculation of "risk". The analysis can be performed for a system baseline condition and for the system with various mitigation packages implemented. This process can be used to estimate the benefit versus cost of each package and used to prioritize mitigation approaches. Recommendations are made for enhancements to AWWA J100.
Ash C.,Degenkolb Engineers
Structures Congress 2015 - Proceedings of the 2015 Structures Congress | Year: 2015
Once finished in early 2016, the Ocosta replacement elementary school in Westport, WA will be the first tsunami vertical evacuation structure in the country. Tsunami-resistant design for the building was performed using provisions which will be published in ASCE 7-16. A benchmarked site-specific inundation model was used for hazard characterization. The school structure was designed to resist hydrostatic, hydrodynamic, scour, and impact forces through various strategies. Pile foundations were designed to resist potential liquefaction at the site and provide residual gravity and lateral resistance with the upper 3.7 m of soil assumed to be scoured. Concrete shear walls were designed to resist seismic and inundation-related lateral forces and offer toughness and ductility to resist impact loads. Structural steel gravity columns were designed to resist expected impact loads and moment-resisting beam-column connections at the refuge level provide alternate-path progressive collapse resistance for unexpected impact forces.