Fewer cross-ties, simpler link beams and less fire protection. The nearly 1.4-million-sq-ft 200 Park high-rise in San José, Calif., though only 300 ft tall, has taken Seattle’s 850-ft-tall proof of concept for SpeedCore—a novel modular steel-plate shear-wall sandwich system—to new heights. And the creators of the 19-story office building have demonstrated again, but with fewer aches and pains, that SpeedCore quickens the pace of construction, especially compared to a steel frame with a leading concrete core.
200公园is on budget and schedule for substantial completion at the end of May 2023. But SpeedCore is done. “Everything went pretty darn smoothly,” says Kevin Englund, a vice president of operations for 200 Park’s general contractor, Level 10 Construction, which declined to provide the value of its guaranteed-maximum-price contract.
使用SpeedCore，机组人员在核心的脚后跟上竖起了重力框架，以至于两个系统在彼此之间大约一周之内就达到了顶峰。
Photo courtesy Level 10
上个月，大约六个月后，铁工队在两个核心登上了两个核心之后大约一周后，达到了200个公园的钢铁上层建筑。尽管该建筑物铺有54,000平方英尺的板板，但与带有混凝土芯的钢架相比，2000万美元的公园团队削减了三个月的时间和1000万美元（或5％至7％）。
“这是一项成功的工作，”制造商 - 主管Schuff Steel项目经理Ryan Cooke说。他补充说：“没有索赔，也不会有任何要求。”
200年公园只有300英尺高,to accommodate height restrictions because it is near the airport, but it has 54,000-sq-ft floor plates.
Rendering courtesy of Gensler
上层建筑“很好,”同意的情况y Kraning, a director of real estate development for developer Jay Paul Co., which is considering using SpeedCore again. Declining to offer specifics, Kraning says the system reduces expenses for general conditions. Also, the building will generate income sooner.
In a sense, Seattle’s Rainier Square Tower served as 200 Park’s 850-ft-tall mock-up (ENR 3/2-9/20, p. 22). The dos and don’ts gleaned from SpeedCore 1.0, open since last year, were passed to SpeedCore 2.0’s team by Ron Klemencic, chairman and CEO of Magnusson Klemencic Associates (MKA). Also ENR’s 2018 Award of Excellence winner, Klemencic is the mastermind behind the nonproprietary SpeedCore.
As structural engineer for both buildings, MKA is the only common thread between the Seattle and San José jobs. “We had a lot of faith in Ron and his abilities,” says Casey Wend, also a Level 10 vice president of operations.
Installed sandwich panels are filled with a grout-like concrete. At 200 Park, SpeedCore begins one level below grade, rather than lower down within the mat foundation, which would have been simpler.
Photo courtesy Level 10
Level 10 had no reservations about taking on a cutting-edge approach used only once before—but not before it put the system under a microscope. “We did a lot of research, toured Rainier Square, talked to the steel erector,” says Level 10’s Englund.
Christopher Payne, 200 Park’s senior project architect for Gensler, calls SpeedCore “an amazing system.” The walls of a concrete core for the 19-story building in earthquake-prone San José would have been 6 in. thicker. That would have eaten up leaseable space, he says.
Though Jay Paul and Level 10 had never worked with MKA or Gensler, the 200 Park team had trust and a collaborative way of working, which are critical to the success of SpeedCore, says Jay Paul’s Kraning.
Hollow H-modules stack to form doorways in the core.
Photo courtesy Schuff
One Innovation Among Several
Benedict Tranel, Gensler’s principal-in-charge, considers SpeedCore just one innovation among several at the development, which is the first new speculative office building downtown in nearly a decade. The LEED Gold building, which is all-electric, is connected to a much bigger story in Silicon Valley, related to urban densification, mass transit, smart growth and putting the brakes on suburban industrial sprawl, says Tranel.
One innovation relates to parking. In addition to four levels in the basement, there are three levels of “convertible” stacked parking above grade, camouflaged by the curtain wall system. If parking demand declines due to plans for high-speed rail and other mass transit, the above-grade garage levels, which have high ceilings, can be converted into office space.
200公园’s trapezoidal floor plate is twice the size of a typical office floor in San José, says Tranel. To manage the scale, Gensler broke office floors into six “neighborhoods,” each with a 5,000-sq-ft terrace. The stacked double-story-height terraces, lined with windows, will bring daylight indoors and provide access to the outdoors at every floor.
200公园incorporates lessons learned on Seattle’s 850-ft-tall Rainier Square Tower—the first SpeedCore project.
照片由MKA提供
SpeedCore is a prefabricated system of cross-tied plate-steel modules. In the field, modules are stacked like Legos, welded together and filled with aggregate-free 10,000-psi concrete through 11-in.-dia holes.
MKA has been developing the system for at least 15 years, long before the American Institute of Steel Construction branded it SpeedCore. 200 Park’s team benefited from recent structural and fire tests at Purdue University and the University at Buffalo, spearheaded by Klemencic and sponsored mostly by AISC and the Charles Pankow Foundation.
For structural, that translated to a 38% reduction in the number of tie rods that couple the steel plates. For fire protection, research showed that “fire resistance is far in excess” of the required 3-hour fire rating for core walls at least 24 in. thick, says Amit Varma, director of Purdue’s engineering laboratory and a peer reviewer for 200 Park. The tests also showed the sandwich walls need vent holes to relieve steam buildup—and pressure—during a fire, created when moisture in concrete heats up.
具体模型helped Level 10 work out the flow and quality of the grout-like concrete fill for the modules, eliminating field surprises.
Photo courtesy Level 10
Fire protection is still required for the floor system-to-core connections. After analysis, 200 Park fire protection engineer SLS Consulting determined that 3 ft of sprayed-on protection is needed around the connections to ensure they perform comparably to rated assemblies. Research to eliminate this protection through engineering is underway, but won’t be available for a year, says Jeremy F. Hasselbauer, MKA’s project associate.
还正在进行开发现场螺栓固定版本的SpeedCore的工作。克莱米奇的希望将使该系统更具吸引力，对东海岸的勃起器，其中一些人警惕了如此多的野外焊接。
SpeedCore offers several benefits. The core and surrounding steel gravity framing can be built concurrently since there is no waiting for the core concrete to cure. And there is no rebar congestion common to buildings in high seismic zones.
Internal trussing to stiffen modules during stacking, transport and erection plus other means-and-methods items had to fit around myriad tie rods.
Photo courtesy Schuff
A SpeedCore job is considered safer and better, proponents say. With prefabrication, there is easier dimensional control. Much of the work is done at waist height in the fabrication plant.
In the field, at each level, the surrounding metal deck doubles as a work platform. There are simple steel-to-steel connections from the floor framing to the core. And there are no forms to jump.
Apart from not being time-tested, SpeedCore’s biggest process demand is that the design team must set and coordinate all core wall penetrations and openings much earlier—before the fabricator details and cuts the panels. Steel is not nimble and field changes can be costly.
尽管MKA正在采用SpeedCore项目，包括在波新利18备用网址士顿，圣何塞和加利福尼亚州奥克兰，但该系统并没有像野火那样赶上。迄今为止，MKA是唯一使用该系统积极的工程师，该工程需要更复杂的基于性能的设计。
从地下室混凝土核心的转变SpeedCore was accomplished through steel stanchions, surrounded by rebar and then concrete.
Photo courtesy Level 10
因此，每个SpeedCore（也因为它尚未在规定代码中）进行了当地管辖权的特殊批准，这意味着同行评审。为了及时批准，必须在设计阶段要比习惯更早地提醒建筑官员。
200 Park还需要结构性同行评审，因为该建筑物高于240英尺，并且由于防火保护幅度减少而进行特别审查。
该市根据《建筑法典》中的替代方式和方法规定考虑了该项目。为了获得结构批准，设计团队遵循了高大建筑的基于绩效的地震设计指南，以验证该建筑物的规划部副工程师丹·陈（Dan Chen和代码执行。
Trucks brought some of the 14-ft-wide modules, weighing as much as 15 tons, from a fabrication plant 700 miles from the jobsite.
Photo courtesy Level 10
To boost comfort levels with the system, SpeedCore design tools and standards are coming. A guide for wind, quakes and fire is due out this year. The 2022 AISC Seismic Provisions for Structural Steel Buildings—AISC 341-22—will contain requirements for designers. The provisions and commentary are based on the Purdue and Buffalo research.
ASCE 7-22 Minimum Design Loads and Associated Criteria for Buildings and Other Structures includes SpeedCore as a permitted seismic force-resisting system, referencing AISC 341-22. And the 2022 AISC Specification for Structural Steel Buildings will include SpeedCore provisions where wind forces govern, not seismic.
Though there are similarities, there also are differences between the two SpeedCore jobs. At Rainier Square, the foundation mat concrete was placed around SpeedCore’s base, which is preferable. At 200 Park, because construction had to start quickly, crews had to cast the mat before SpeedCore was ready. Consequently, the basement has a concrete core.
James O. Malley, group director of Degenkolb Engineers and a peer reviewer for both SpeedCore projects, calls the transition from the superstructure’s SpeedCore to the concrete structure “the most tricky detail” of 200 Park. “There was a lot of discussion because the force transfers [from above] are pretty significant,” he says.
Nevertheless, the transition from concrete to steel “proved the viability of the use of SpeedCore with reinforced concrete construction,” says MKA’s Hasselbauer.
After a lower tier is complete (bottom graphic, blue), crews erect next two-level tier with 28-ft-tall boundary elements (green) first, followed by lower-level infill modules (red) and surrounding framing, then upper level infill modules (yellow). Concrete (module graphic at top) fill trails the modules by about four floors. 200 Park’s 54,000-sq-ft floor plate needed two SpeedCores.
Module graphic courtesy AISC; Building frame (middle) with cores courtesy MKA; 3D grapic (bottom) coutesy Schuff
*Click on the images for greater detail
Two Structural Cores
该建筑物的横向抗压系统受地震需求较高的要求，该系统较短，高层较短，由钢筋混凝土核心组成，直至B1级（低于等级），以及从B1到20级的机械阁楼的SpeedCore。
大地板促进了一个两杆北芯，长62英尺，一个单细胞的南部核心，长33.5英尺，它们之间有一个建筑核心。这三个核心长152.5英尺，宽43.5英尺。
SpeedCore consists of ½-in.-thick plates cross-tied by steel rods spaced every 12 in. up to level 6, where ductility is required during a quake, and 18 in. above. Wall thickness varies between 2 ft and 3.5 ft at the base, reducing to between 2 ft and 3 ft about halfway up the building.
SpeedCore的两层单元由28英尺高的框列之间的两个堆叠模块组成，称为边界元素。门口的耦合模块为H的形状。
The latest research also enabled simpler link beams over doorways. Studs, easier to fabricate, replaced all vertical ties and about 90% of horizontal ties.
SpeedCore splices into the basement core for one full story. The core splice is from B2 to B1, as per the peer reviewer’s suggestion, to separate the complicated splice detailing from the complicated drag element at grade, says Hasselbauer.
The splices are accomplished using steel stanchions embedded in the concrete core walls. Stanchions are built-up I-shapes with flange plates up to 4 in. thick, typically spaced 4 ft on center. They match and weld into SpeedCore walls above.
Stanchion rebar congestion is so intense that crews from Level 10, which self-performed concrete work, had to hand-set the concrete around them.
The ground-level load-transfer diaphragm from the steel frame to the basement is a 2-ft-thick concrete flat slab. At the transfer level, studded drag element plates spliced to the SpeedCore panels extend into the slab.
Schuff started budgeting for the job, which has 4,000 of its 10,000 tons of steel in the core, in January 2020, a month before Level 10 issued its request for proposals.
焊接立即遵循每个核心层的安装，并在放置填充之前完成，以下几个级别。板上的切口必须在此过程的早期建立，以促进预制并避免昂贵的野外校正。
Photo courtesy Level 10
Five Lump-Sum Bids
Level 10, which received five lump-sum bids, sought a steel contractor that could accommodate the work without going offshore for plate supply or fabrication. MKA participated in the interviews. “We did quiz [bidders] rigorously,” says Klemencic.
根据第10级，Schuff根据其有能力的价格和详细，制造，处理，卡车运输和勃起的全面方法获得了奖项。
与Rainier Square一样，MKA指定了两个全尺寸的核心模型 - 一个用于钢，另一个用于混凝土填充物，以计算材料流。10级的Englund说，这笔500,000美元用于模型的花费很好，因为“该领域没有问题”。
每个54,000平方英尺的办公室级别分为六个“社区”。每个社区都有一个露台，可让居住者放在室内，并让乘员走到外面。
Rendering courtesy Gensler
Schuff finished the 18.5-ft-tall steel mock-up, L shaped in plan, in January 2021. It mimicked a typical 4.5-ft splice height above a working floor. The structure allowed crews to scrutinize vertical and horizontal splices, a coupled H-panel, uncoupled panels, boundary elements and all means-and-methods items.
“A lot of the lessons learned from the mock-up resulted in redetailing,” especially means-and-methods items, says Schuff’s Cooke.
Schuff had two fab shops working exclusively on SpeedCore, one 700 miles from the jobsite in Phoenix and the other 75 miles away, in Stockton, Calif.
There was cradle-to-grave coordination and integration for detailing, fabricating and erecting, says Dave P. Wright, Schuff’s director of preconstruction.
14英尺高的模块重约12吨至16吨，长达38英尺，必须旋转，举起，堆叠，存放，存放，放在平床和卡车上，没有任何变形或变形。为了使它们保持正方形和平直，Schuff在链路梁上的所有模块和外部桁架中都集成了内部桁架。
Means-and-methods steel accounted for 20% of the overall 4,000-ton core weight. This includes internal trusses, backing, erection aids and picking lugs. For each module, the welded cross-ties, their nubs dotting surfaces, were added last. There are 65,000 ties in the core.
BIM帮助避免了冲突。Schuff还创建了一个3D动画来研究勃起序列。新利18备用库克说：“我们必须围绕原材料和拉杆工作。”他补充说，具有挑战性的工作“并不适合所有人”。
For steel erection, two tower cranes, initially freestanding, were located outside the structural steel frame. For the eventual building tie-in, MKA designed temporary members to transfer tower crane loads to the SpeedCores. In the scheme, modules had to have concrete fill prior to crane jumps.
As the schedule was a driver on the project, Level 10 did not want crane jumps or steel erection activities to wait for the fill operation. Before module fabrication, Schuff’s erection engineer, Simpson Gumpertz & Heger, evaluated the core for the interim construction loads, without the fill. Consequently, Schuff installed additional internal bracing in the modules, at the shop, to allow the tie-ins without filled modules.
由于靠近Norman Y. MinetaSanjosé国际机场，联邦航空管理局对北吊车进行了一次跳跃，然后被横梁起重机取代。这减慢了北核的勃起几天。南起重机跳了两次。
An advantage of the innovative modular core is that the steel frame is erected in concert at every tier.
Photo courtesy Level 10
Above-grade steel erection started July 15, 2021, with the south core. Schuff used two raising gangs working a single shift, six days a week.
The general sequence of erection was: (1) install two-tier core box columns; (2) set first tier infill modules; (3) erect surrounding gravity columns and girders to connect to first-tier modules; (4) set second-tier infill modules and; (5) erect the second level gravity framing to tie into the core walls and boundary elements.
Welders worked just below the current active core level. Concrete fill trailed by four or five levels. The operation could not trail by more than eight levels.
For typical floors, the pace was five work days per level for both the core and surrounding framing, says Schuff.
Crews topped out the building on Jan. 20, after about six months. Schuff figures it could have been a few weeks sooner if not for FAA crane restrictions.
200公园’s creators are now veterans of SpeedCore 2.0. Based on that, Level 10 thinks for the next SpeedCore, they could skip the mock-ups. The caveat: only if Schuff was on board and Level 10 placed the fill.
Klemencic agrees that mock-ups might not be necessary for the next Level 10-Schuff SpeedCore, but only if the same individuals and crews are used.
Schuff的Cooke同意：“在圣何塞市中心，我们已经建立了一个20层的模型。”
