Construction Op

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สำหรับใช้อ้างอิงในวิชา Design of Construction Operation 185430

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http://www.cityu.edu.hk/CIVCAL/book/misc_advanced.html

Advanced Technology Examples of Advanced Technology Employed in the Construction of Buildings in Hong Kong
Steel formwork is becoming quite common, especially in buildings with regular, identical or repeated layout. The one in the photo is used in the construction of Harmony blocks, a common building technique employed in Housing Authority projects.	The 'Jump Form', another type of highly mechanised formwork system, used in a Concord block public housing project. This system can lift itself up by a jacking device when the concreting work of a floor is completed. As individual formwork panels are hung under a sliding rail, the system can thus save a lot of time and effort in the striking and placement of the formwork panel.
A closer look at the Jump Form shows that the track rail can enable the formwork panel slide into position.	Steel formwork for beams is uncommon. The example shown is specially designed for the new Headquarters building for the Hong Kong Jockey Club. It is a composite construction making use of precast secondary beams and sub-slabs to form the podium structure.
Formwork is one of the most challenging elements of work in the construction of high-rise buildings, mainly due to complicated spatial, loading or scheduling requirements. Though there are many advanced formwork systems available, traditional timber formwork is still widely used for building construction in Hong Kong due to its flexibility in meeting with various layout requirements.	Another common type of steel formwork is of a vertical attaching nature, which can 'climb' in a free-standing manner. This is more suitable for situations like a central core of a building which has lift shafts.
Another example of specially designed steel formwork to suit a particular shape and purpose: the example shown here was used as a pier for an elevated motorway.	Formwork shaped like shutter panels can be used in complex arrangements, like the one here for the wall of a circular ramp.
The principle of formwork is simple, but performing the installation under site conditions may be quite difficult. Depicted here is the erection of the final section of formwork for a 9 m circular column which encases the steel stanchion for a structural steel building.	'Table Form' made of aluminium sections is growing in popularity, especially for commercial/office buildings making use of flat-slab design. The one as shown here is the Gateway II project.
The 'Climb Form' under the VSL system, was used for the Lee Garden Redevelopment project.	The Jump Form system was used for the Cheung Kong Center project.
The principle of using Table Form seems simple, but many connecting details require solution before satisfactory application. The example here, with the floor slab connecting to the central core, best illustrates the situation.	Another tailor-designed formwork was used to construct the elevated expressway at Ma Wan, which is part of the Lantau Link. The formwork was composed of a gantry frame that hung the shutter panels for the inner-wall of the box-section expressway. Again, it could be slid to a new position on track rail to repeat works conveniently.
The VSL Climb Form utilised to construct the building core for the International Finance Centre adjacent to Hong Kong Station at Central. Two sets of identical formwork were installed to form the large regularly shaped central core. This helped acquire the best operational efficacy by splitting the core into two halves, as well simplifying the construction and size of the formwork.	Close-up of one set of the two identical Climb Form systems used in the construction of the International Finance Centre. Since the size of the form has been reduced by dividing it in two, the main supporting frame for the formwork system is obviously much simpler than the one used by the Lee Garden Redevelopment project.
A panoramic view from the top deck of the Climb Form system for the Lee Gardens Redevelopment project. Main features such as the main supporting frame, the hydraulic jack rod, and the wall section with reinforcing bars already in place, can be clearly seen here.	A formwork system combining steel trusses and glass-reinforced plastic shutters were used to construct the complicated roof of the Ground Transportation Centre situated at the entrance to the Airport Terminal building.
A combined formwork and falsework system used in the new airport terminal. The whole system can be released and slid to a new position on track rail. The system can best serve where a lengthy, repetitive section of elevated platform is required Ñ like the passenger unloading deck shown here.	Low-rise buildings of structural steel construction are rarely used in Hong Kong, but a few examples are found in the new airport at Chek Lap Kok. The example shown here makes use of metal panels as the external cladding system. (Asia Air Terminal)
Cladding system employed for the Cathay Pacific Catering Services project at Chek Lap Kok.	Another example of metal-panel cladding: the Air Mail Centre at Chek Lap Kok operated by the Hong Kong Post Office.
The challenge of providing building services to modern high-rise buildings taxes technological and engineering concerns. Accommodating the services safely, neatly and effectively inside the limited space of building in the design is the goal. Shown here is a switch room with hundreds of power cables, demonstrating the complexity of such services. (The Centre)	One of the basic provisions for grade A office space is a serviceable floor providing access for IT cabling. The one shown here is a typical raised-floor system with a 250 mm floor void. The separating panels inside the floor (and in the ceiling) are fire breaks made of cement board.
Large amounts of glass are often used as roofing in the form of skylights. The one seen here (Festival Walk) uses over 5,000 sq m of glass as skylight to provide natural illumination for the river-like atrium. To provide a clear span of 30 m with strict waterproofing and dimensional performance is an exceptionally demanding requirement.	Shown here are construction works for the Airport Railway tunnel section in the Western Kowloon Reclamation. The sides of the 8 m excavation are supported using steel sheet piles and further stabilised by a complicated steel strut frame. Control of ground water was crucial on this newly reclaimed land. The RC tunnel section was then constructed upward from the bottom of the excavation.
A drilling machine was used to prepare bore holes for the insertion of steel tendons to form the ground anchor.	The photo shows a 12 m deep excavation for the Airport Railway tunnel section at the Central Reclamation near Hong Kong Station. A relatively 'obstacle free' method was used to support the excavation, and soldier piles supported laterally by ground anchors were also employed.
The top-down construction method is virtually the only method suitable for the construction of deep basements on a large scale. One irresistible advantage of this method is that substructure and superstructure work can be carried out at the same time. The one seen here depicts the basement entrance for the Cheung Kong Center project, which best illustrates the method.	Top-down basement construction: the permanent RC structure at the top has been completed but remains supported on temporary steel stanchions, while the excavation and construction work to the lower basement is yet to be continued. (Lee Gardens)
Another complication in the construction process involves sub-structures: the foundations, extensive groundwork, basement construction. The work seen here is a heavily reinforced 4.5 m raft which acts as the foundation cap for the building. The steel shore at the centre, which radiates outward to support the sides of the excavation, can also be seen.	The Festival Walk project presented an extremely complicated case with very difficult substructure works. Complicating factors included the huge site area, the inconsistent subsoil conditions, the MTR tunnel cutting across the site, the top-down basement construction method used and the segmental phasing arrangement in the overall construction.
Another feature of top-down construction is that the ground floor slab (indeed, any slab close to ground level) is cast first as a starting level to provide the necessary rigidity to the side supports. This example, from the Festival Walk project, best illustrates the arrangement.	This drilling rig works with a steel casing for soil support during the excavation process, drilling bit for the actual digging/drilling, soil grab for the removal of soil and chisel hammer to break harder rock, can be used to construct concrete bore piles up to 2.75 m in diameter.
One reason for recent advances in building construction is the steady improvement of machinery used in the construction of foundations. This example is a compact-sized drilling machine which can be used to construct in situ concrete bore piles ranging from 150 mm to 450 mm in a congested urban environment.	The reverse-circulation drilling machine, combined with a rig-like turntable mounted on top of the steel casing, requires a set of suction pumps and a de-sanding machine to facilitate drilling. Soil or gravel is pumped up from the excavated trench by ground water circulation. At the same time, the de-sanding machine removes soil particles from the ground water and recycles it in the drill hole.
Most recent curtain wall systems used in Hong Kong are the unitised system: The wall is composed of identical panel units and attached to the main structure directly without a main bearing frame. The photo shows the installation of curtain wall at the Lee Gardens Redevelopment project.	Difficulties encountered in the installation of curtain wall are often due to irregular building shape and awkward angles. The picture illustrates these problems (The Centre).
Modern construction strives to provide an attractive, energy-efficient, weather-tight external envelope. Curtain wall is one of the most popular options for commercial and office buildings. This example depicts the main skeleton of a building before curtain wall units are attached to its outer face.	Another new machine, the reverse-circulation trench cutter or hydrofraise, is very efficient for the construction of diaphragm wall. Working similar to the principle of reverse circulation drilling machine, it requires bentonite slurry as the recycling medium instead of ground water. Several pairs of drum cutters at the tip of the hydrofraise do the actual cutting. The box-sectioned cutter rack produces a section of uniform thickness for the diaphragm wall panel.

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February, 2009

Featured Article -

Steel Provides Answer to Building on Top of Existing Parking Garage

Adam Abbes Yala, P.E., Ph.D., Ken Maschke, P.E. and Kevin Jackson

Constructing a new building on top of an existing structure can sometimes feel like trying to fit a square peg into a round hole. Several years after construction had stalled on a prominent development, Thornton Tomasetti was asked to re-engineer the unfinished plans for a mid-rise building near Chicago’s Magnificent Mile.

A new development team purchased the property and commissioned an architectural design that varied greatly from the original plans. The key change was from a 13-story square donut shaped tower to a 25-story tower with an elliptical floor plan to be built on top of an existing 8-story concrete garage. The new tower would be centered above a previously designed light core. This loaded the interior columns and foundations beyond their designed capacity. A 6-foot deep transfer mat and a 16-footdeep transfer girder were required to spread the load to columns with adequate capacity. Overcoming these challenges also influenced many other aspects of the building’s design.

Thornton Tomasetti was asked to re-engineer the unfinished plans for this mid-rise building near Chicago’s Magnificent Mile.

The construction team likewise faced challenges with the site. A parking garage and grocery store were located in the existing podium. The need to keep these facilities open during construction greatly affected construction sequencing.

The site is located in Chicago, Illinois, just one block away from Michigan Avenue. When development of the site was first proposed in the late 1990s, planners envisioned a multipurpose development to revitalize the area.

Facing an economic downturn around the turn of the millennium, the project was divided into phases. The first phase only included a parking garage and grocery store on the east third of the site. However, the foundations and columns were constructed to support a future 28-story hotel tower on top of the parking garage. Despite several setbacks, phase one was finally completed in 2004.

An ownership change allowed development of the site to proceed. The new developer continued the phased approach. A new team of consultants and contractors also joined the project. In an effort to respond to market changes, the new design team abandoned the hotel concept and began work on a residential tower. The new tower floor layout varied significantly from the proposal that had been used to size the base columns and foundations. Instead of a square hotel tower with a large light core, the new design had a football-like shape and was centered over the base building (Figure 1).

Figure 1: 9th floor structural plan shows column connections to existing structure.

Existing Base Plan

The existing parking garage plan was based on a regular rectangular grid. From east to west, ten column lines were typically spaced at 22 feet 6 inches on center. In the north-south grid, five column lines were typically spaced at 33 feet 9 inches. The perimeter bays of the structure were supported by concrete columns ranging in size up to 3 by 6 feet. However, the four center columns were much smaller, only 3 feet square. The new residential tower would be centered on the podium, about column line-C. Further, the new tower’s column layout did not match the existing column grid at all.

The existing structure included eight levels of parking, a supermarket, and many of the MEP systems required for the planned residential tower above. The parking levels were supported on cast-in-place post-tensioned slabs. Lateral forces were resisted with a system of concrete moment frames. Ramps between parking levels served to further stiffen the base against lateral movement.

Structural Design

The most immediate problem faced by the design engineers was how to support the new tower. The tower columns did not align with the existing grid, and the structure itself was centered over columns and foundations that were not designed for such loading. In addition, the podium’s lateral system was primarily located outside of the envelope of the planned tower.

To transfer the tower column loads to the existing columns below, the engineer used a 6-footthick concrete mat at the interface between the new and existing structures. The mat also served to transfer the lateral loads from the tower’s structural system to the existing parking garage’s lateral system. This massive concrete mat would need to be poured 100 feet above grade. Even with a 6-foot thick mat, initial analysis revealed that too much load was being distributed to the slender interior columns. To alleviate some of the loads from the smaller columns, a 16-foot deep transfer girder was introduced along the central column line (grid line-C). The transfer girder spans through the four interior columns to the two large exterior columns on each side. Each column is engaged, and vertical load is transferred according to the relative stifness of each column section and the transfer girder.

Complete structural model.

Finite element analysis (FEA) software was utilized to determine the vertical load distribution between transfer elements and existing columns. The columns were modeled with spring stiffness equivalent to their elasticity and foundation information. The FEA programs also assisted in selecting the appropriate reinforcing of the mat. All aspects of the concrete design were performed according to the ACI 318. This included capping the highest strength of concrete permissible in strength calculation at 10,000 PSI (ACI), as used in the transfer girder.

About 500 tons of steel reinforcing were required for the transfer mat. The vast majority of this steel was used as longitudinal reinforcing. However, the design for resisting punching shear at both the existing columns and the transferred steel columns required special attention. The resulting detail called for shear stirrups with a varying number of legs to run between the mat’s reinforcement layers.

An early analysis of the existing lateral force resisting system indicated that each of the exterior columns would need to be engaged at the tower’s base. There was not sufficient diaphragm strength in the PT slab to distribute the entire tower shear from the columns on lines B and D to the full moment frame system. To minimize the amount of concrete necessary, the 6-foot transfer mat spanned only from grids B to D. Beyond that, 6-footdeep by 3-foot wide beams engaged the mat with the existing exterior moment frame.

In the Chicago area, concrete structures are preferred for residential buildings. However, in order to make the transfer mat and girder system economical, the residential tower needed to be as light as possible. A steel framing system was found to be the best option. W16 beams with 3-inch composite deck and light-weight concrete typically spanned up to 30 feet. This system provided a sufficient diaphragm so that the floor translated as one plate under lateral loading. To pursue weight savings in the lateral system, steel braced frames were initially considered. However, the oblong tower shape and a floor plan optimized for maximum tenant space left little room for the bracing lines.

Shear reinforcement detail.

The complexity of the structure, plans for adjacent high-rises, and an unpredictable local wind climate convinced the design team to seek wind tunnel testing for the building. Combining mode shape data provided by the engineers with the results of scale model testing in the wind tunnel, specialists concluded that the light-weight steel tower would likely exhibit higher than acceptable lateral accelerations. The local wind environment, funneling winds off of Lake Michigan, had the possibility of exciting the tower in a twisting motion. Although the building was sufficiently strong to resist these winds, the particular motion had the potential to upset the occupants.

The design engineers immediately began discussing options with the architect and developers. With sales beginning on the proposed structure, it was undesirable to restrict the tenant space in any way. The amount of time available to the design team to make a final decision about the new lateral system was also very limited. A building-design-specific finite element analysis package allowed the engineers to consider several possible structural arrangements in the short time frame. The program also quickly computed the building’s mass properties and mode shapes. These values were critical to calculations performed by the wind tunnel experts.

Placement of reinforcement for second lift of transfer mat.

Without the freedom to add mass to the building, the structure’s stiffness played the biggest role in reducing the uncomfortable wind-induced accelerations. To increase stiffness, the engineers borrowed some structural design elements typically used in commercial high-rises.

First, the engineers proposed changing the lateral system to a stiff cast-in-place concrete shear wall system. Combining concrete core walls with steel framing and columns is common practice in Chicago. Several options for the concrete walls were considered, and, eventually, a plan was approved that included a slender wall extending the full north-south width of the tapered end of the building. Large openings in the wall were required to accommodate the condominium units’ floor plans. For even greater stiffness in the east-west direction, a hat truss was added at the 31st floor to link the braced cores located at either end of the tower.

Figure 2: Inter-story drift in the east-west direction.

Figure 2 illustrates how the evolution of the building’s lateral system improved stiffness and reduced inter-story drift. The switch to concrete walls alone was not enough to fully mitigate the potentially disturbing building motion. Adding the hat truss significantly reduced drift in the east-west direction, especially at the upper levels. In one design, outrigger trusses were planned to link the core with the exterior columns in order to engage these elements in the same way that a stay cable supports a ship’s mast. However, the outriggers had little affect on the building behavior. Several iterations of slightly tweaked computer models allowed the engineers to arrive at a structural solution that reduced the building period by over 30% and uncoupled the torsional mode from the primary modes.

To minimize the additional weight applied to the transfer mat by the concrete core walls, the thickness of the shear wall was reduced half-way up the wall, where the stiffness demands were not as great. However, due to the schedule constraints, the steel framing had already been ordered and cut to length. Rather than scrapping the already purchased steel, the design engineers investigated and approved the use of lightweight concrete in the upper floors while maintaining a constant wall thickness. This approach had the added benefit of allowing the climbing form system to move seamlessly through the transition with no adjustment. As a further weight savings, planned cast-in-place concrete stairs were replaced with lighter metal stairs.

Construction

Adaptation of the parking garage base to support the 25-story residential tower proved to be a big construction undertaking. Simply supplying all of the construction materials was a logistical challenge. Placing these materials required a significant amount of man power, but ensuring that the elements were properly and safely installed required further engineering.

The first major construction challenge was figuring out how to support six feet of wet concrete (the mat) from a series of lightweight post-tensioned parking decks. The supermarket on the 1st floor had to remain open throughout construction, so it was not possible to shore down to grade. Moreover, the existing PT-slabs could not support all six feet of wet concrete, even if the load was shared among 6 of the existing parking decks. To resolve this problem, the engineers redesigned the mat to be constructed in two lifts. The first lift had a thickness of 3 feet 6 inches. The wet weight of concrete could be supported by shoring that extended 6-levels below the mat. This lift included additional shear transfer reinforcement for the second lift. After seven days, the first lift was able to support its own weight and the second lift was poured with the same shoring in place. In this way, the parking decks were actually re-opened ahead of schedule.

After the mat had been poured, work immediately began on the shear walls. A climbing slip form quickly allowed work to proceed upward on the wall ahead of the steel floor framing and columns. The shear walls would always precede the floor framing; but, if they extended too high, the walls would potentially be exposed to wind forces that they had not been designed for. The main wall running in the north-south direction ran almost the full width of the narrow profile of the building, exposing the connected east-west walls to forces that would have been shared with the twin core in the final building condition. Again, finite element analysis was performed to determine that the core could advance 6 stories above the completed floor diaphragm.

The advancing shear walls created another obstacle with the tower crane connections. Since the tower crane would be required to service the entire site, it would need to lead the shear walls as well, forcing a portion of the tie-in steel to be integrated into the floor framing and the uppermost tie-in location to be made to a floor with no diaphragm. Further complicating the situation was the tower crane location. Due to site logistics, the crane was located outside the footprint of the lower podium creating a cantilever of over 50 feet from the tower crane to the connection to the shear wall. To prevent axial loads from being transferred through embed plates designed for gravity only, some of the steel floor framing connections to the core were intentionally left loose until the deck was poured.

Model to compute stresses on exposed shear walls.

Creative Solutions

With some engineering, a square peg can be fit into a round hole. In this case, a 25-story elliptical residential tower was engineered to fit on an existing square podium. Creative solutions for distributing gravity load and resisting lateral forces enabled the developers to create a building that could succeed in the current economic environment - even if that meant a drastic departure from the originally designed program.

The new residential tower is supported above an existing 8-story podium by a 6-foot thick concrete mat. To further distribute the load to columns with adequate bearing capacity, a 16-foot deep transfer girder was also necessary. This system required special rebar detailing and a unique construction sequence. Even so, it was critical for the tower to be as light as possible. Engineers creatively used concrete core walls and a steel hat truss to stiffen the building and provide a comfortable living environment for the future occupants. Finally, the construction of the tower presented additional challenges that were likewise overcome by the design engineers.

In the end, creative solutions to design and construction problems facilitated the construction of a new landmark in the Chicago Skyline.▪

All images courtesy of Thornton Tomasetti Inc.

Adam Abbes Yala, P.E., Ph.D. is a senior associate with Thornton Tomasetti. Adam may be reached at [email protected].

Ken Maschke, P.E. is a project engineer with Thornton Tomasetti. Ken may be reached at [email protected].

Kevin Jackson is a senior project engineer with Thornton Tomasetti. Kevin may be reached at [email protected].

This article is available in Adobe PDF format:

 

Steel Provides Answer to Building on Top of Existing Parking Garage

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New building design withstands earthquake simulation

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ANN ARBOR, Mich.—Researchers at the University of Michigan simulated an off-the-charts earthquake in a laboratory to test their new technique for bracing high-rise concrete buildings. Their technique passed the test, withstanding more movement than an earthquake would typically demand.

The engineers used steel fiber-reinforced concrete to develop a better kind of coupling beam that requires less reinforcement and is easier to construct. Coupling beams connect the walls of high rises around openings such as those for doorways, windows, and elevator shafts. These necessary openings can weaken walls.

"We simulated an earthquake that is beyond the range of the maximum credible earthquake and our test was very successful. Our fiber-reinforced concrete beams behaved as well as we expected they would, which is better than the beams in use today," said James Wight, the Frank E. Richart Jr. Collegiate Professor in the U-M Department of Civil and Environmental Engineering.

Click image for higher resolution

Working with Wight on this project are Gustavo Parra-Montesinos, an associate professor in the Department of Civil and Environmental Engineering, and Remy Lequesne, a doctoral student in the same department.

Today, coupling beams are difficult to install and require intricate reinforcing bar skeletons. The U-M engineers created a simpler version made of a highly flowable, steel fiber-reinforced concrete.

"We took quite a bit of the cumbersome reinforcement out of the design and replaced it with steel fibers that can be added to the concrete while it's being mixed," Parra-Montesinos said. "Builders could use this fiber-reinforced concrete to build coupling beams that don't require as much reinforcement."

The engineers envision that their brand of beam would be cast off the construction site and then delivered. Nowadays, builders construct the beams, steel skeletons and all, bit by bit as they're building skyscrapers.

Their fiber-reinforced concrete has other benefits as well.

"The cracks that do occur are narrower because the fibers hold them together," Parra-Montesinos said.

The fibers are about one inch long and about the width of a needle.

The engineers performed their test in December on a 40-percent replica of a 4-story building wall that they built in the Structures Laboratory. They applied a peak load of 300,000 pounds against the building, pushing and pulling it with hydraulic actuators.

To quantify the results, they measured the building's drift, which is the motion at the top of the building compared with the motion at the base. In a large earthquake, a building might sustain a drift of 1 to 2 percent. The U-M structure easily withstood a drift of 3 percent.

The new beams could provide an easier, cheaper, stronger way to brace buildings in earthquake-prone areas.

The researchers are now working with a structural design firm to install the beams in several high rises soon to be under construction on the west coast.

This research is funded by the National Science Foundation under the Network for Earthquake Engineering Simulation Program.

Michigan Engineering:
The University of Michigan College of Engineering is ranked among the top engineering schools in the country. At more than $130 million annually, its engineering research budget is one of largest of any public university. Michigan Engineering is home to 11 academic departments and a National Science Foundation Engineering Research Center. The college plays a leading role in the Michigan Memorial Phoenix Energy Institute and hosts the world class Lurie Nanofabrication Facility. Michigan Engineering's premier scholarship, international scale and multidisciplinary scope combine to create The Michigan Difference. Find out more at http://www.engin.umich.edu/.

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It's Not Demolition; It's Deconstruction

Carefully taking down three buildings and reusing or recycling as much of them as possible is more than mere demolition. The process is one key to building a new student union at UW-Madison.

Story by Mike Larson, Editor. -- Western Builder, 3/2/2009

Three old buildings are coming down on the corner of Randall Avenue and W. Johnson Street on the University of Wisconsin — Madison campus to make room for a larger multi-use student-union building that will be a focal point for students and guests in the south-central area of campus.

CG Schmidt, Inc., Milwaukee, is the construction manager overseeing both the deconstruction of the existing buildings and the construction of the 194,000-square-foot, three-story modern structure that will rise in their place.

Throughout the project, Madison Environmental Group, Inc., Madison, WI, will provide environmental consulting, help find outlets for reusable and recyclable materials generated by the project, and certify the types and amounts of materials that have been reused, recycled or sent to landfill.

Dan Davis, project team leader for CG Schmidt, the construction manager at risk, and Sonya Newenhouse, president of the project's environmental consultant, Madison Environmental Group, Inc., both say that "deconstruction" is a better term for the process than "demolition."

That's because demolition conjures up visions of buildings being knocked apart without much care for preserving things that can be reused or recycled.

Certainly, some smashing and crunching demolition will be part of the project, but much of the work involves care and painstaking planning.

New Union Will House Many Activities, Be Environmentally Friendly

The new Union South will not only contain space for studying, meetings and offices. It will also offer 60 guest rooms, 185 underground parking stalls, restaurants, a coffee shop, retail space, a full-service grille, an 800-seat ball/banquet room, foodservice preparation facilities, a 300-seat movie theater, a bowling alley, a recreation center; a two-story climbing wall, elevated terraces, balconies suitable for holding social events, and a roof plaza.

The adjoining grounds will offer space for large gatherings such as pep rallies, receptions, farmers' markets, and outdoor entertainment.

Besides being useful, the new Union South is designed to be ecologically friendly and energy efficient.

It will meet either the LEED silver or gold standard set by the U.S. Green Building Council, and will also exceed ASHRAE energy-conservation standards by 40 percent.

To Make Room, Three Old Buildings Must Go

Making room for the new Union South requires deconstruction of three old buildings on the site: the Randall Tower, Hi-Ray Hall, and the existing Union South, which was built in 1972.

Deconstructing the three existing structures, then building and equipping the new Union South is expected to cost about $94.8 million and take just over two years.

The UW Board of Regents will own the new Union South. Wisconsin's Division of State Facilities will administer the completed building, and the Wisconsin Student Union will be its tenant.

Environmental Responsibility Key

Right from the beginning, that group set environmental leadership and sustainability as key requirements.

CG Schmidt project team leader Dan Davis noted, "To earn enough LEED points for silver or gold certification, you not only have to have a sustainable design and minimize construction waste, you also have to recycle nearly all the material created by deconstruction."

"The project plan," says Davis, "calls for 90 to 95 percent of the deconstruction waste to be reused or recycled. CG Schmidt has routinely done that on many projects since 1993. It seems very achievable here."

CG Schmidt subcontracted deconstruction of the three existing buildings to Veit, of Rogers, MN.

Physical work on the project started in January, when workers from Wisconsin's Division of State Facilities began removing furniture, doors, fixtures, and even HVAC components that could be reused at other state facilities.

Early in February, CG Schmidt's abatement subcontractor began removing any asbestos and other hazardous materials that had been identified in the buildings.

As abatement is completed in each building, CG Schmidt crews and Madison Environmental Group, Inc. (MEG) advisors identify and remove materials that could be reused or recycled. For example, MEG found buyers for the acoustic ceiling tiles removed from the buildings.

MEG sustainability consultant and LEED Accredited Professional Kelly Humphry commented, "Reuse makes both good environmental sense and good business sense. Just as one example, there is a demand for used acoustic ceiling tiles in Wisconsin. Although you don't make much money by selling them, you avoid adding to the state's landfill burden and you save the $35-per-ton landfill tipping fee, too."

In mid-February, Veit's heavy hydraulic demolition equipment started hammering away at the brick, concrete and steel of the three buildings that have to be taken down to make room for the new Union South. Deconstruction will take until the end of April.

But even the debris from that part of the job will nearly all be recycled.

Says Davis, "All of the scrap metal will be recycled, and all of the concrete and brick will be crushed and reused on other projects. Only a few things, like commercial roofing material and the previously removed asbestos, will end up in a landfill."

Construction of the new Union South will start immediately after the site has been cleared of deconstruction debris.

MEG's Humphry says, "On some jobs, we help design the recycling system, but the university, CG Schmidt and Veit all are well experienced and have already developed good systems. So our main functions on this project are making sure workers understand the system, verifying the amounts of material recycled, and tracking every pound that leaves the site."

Typically, the sorting system consists of different dumpsters, each assigned to hold only one type of debris — steel, wood, copper, aluminum, and so on. As the dumpsters fill up, they are taken to the appropriate place that will recycle each kind of material.

Overall Project Presents Many Logistical Challenges

As is typical, a project of this magnitude presents a few challenges for the construction manager and team.

One of those challenges, says Davis, is that more than seven entities need to review and approve the design — and any changes to it.

They include the university's board of regents; the Division of State Facilities; the Wisconsin Student Union Council, a student-led design committee; the state Building Commission; the city of Madison; neighborhood groups; and a pedestrian-and-bicycle committee. In addition, a railroad also must be consulted because its right of way runs along one side of the site.

"Everyone's been great to work with," says Davis, "but it still takes a lot of coordination and meetings to make sure everyone is informed, involved and up to date."

Another logistical consideration is maintaining access to a library that sits just behind the construction site and a computer-science building that stands right across the street.

Says Davis, "We need to take care that we sequence the work and designate working locations so that fire exits and other access to the library and computer-science building always remain available. It just means thinking ahead and using insight from our experience."

CG Schmidt Experience With Green Building Dates Back To 1993

CG Schmidt's experience with environmentally sensitive construction and deconstruction stretches back to 1993, when the company demolished and rebuilt a building for the School Sisters of Notre Dame in Elm Grove, WI.

Davis explains that the nuns of the order felt a spiritual connection to the environment and wanted to do the right thing.

Working on that project, the Schmidt family also became aware of ecological issues and wanted to do the right thing by minimizing environmental impact and recycling waste.

After that project, says Davis, CG Schmidt began to incorporate what later became known as green building practices into its projects. "Schmidt was green before it was cool to be," he says.

The company incorporated green building principles into the new headquarters it built for itself between 1997 and 1999. That building, says Davis, still holds the Energy Star rating today.

The Energy Star rating recognizes buildings that rank in the top 25 percent of the most energy-efficient buildings in the country.

Says Davis, "It is a pleasure to work on a project like this new Student Union, which does the right thing for the environment and which will serve so many people for decades to come."