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North Mountain IMS MedicalOffice BuildingPhoenix, ArizonaMichael HoppleFinal Report Integration of Sustainable Structural Elementsand Evaluating Mechanical System EffectsApril 9th, 2008AE 482W-Senior ThesisThe Pennsylvania State UniversityFaculty Adviser: Dr. Ali Memari, P.E.

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Table of ContentsCredits/AcknowledgementsPage 4Executive SummaryPage 5North Mountain As Designed ConditionsBuilding and Site OverviewLoading AnalysisTypical Framing Plans and DetailsStructural SystemsMechanical SystemPage 6Project ObjectiveStructural DepthSustainable Architecture BreadthMechanical BreadthPage 13Sustainable Architecture BreadthEnvironmental Effects of Steel vs. Concrete Building FrameGreen RoofPrecast Concrete Sandwich PanelsPage 15Mechanical BreadthHeating and Cooling Load ReductionRadiant Solar CollectorsPage 24Structural DepthPrecast to Steel FramingPrecast Concrete Sandwich PanelsPage 28Conclusions and RecommendationsPage 35AppendixConcrete Process DiagramSteel Process DiagramRoof R-valueWall R-valueEnergy Model OutputFraming PlansVulcraft Deck TableSeismic Base ShearStory ForcesStory DriftFoundation Comparison TakeoffsPrecast Concrete Sandwich Panel DesignPage 36[Hopple‐Final Report]Page 3

Credits/AcknowledgementsPenn State Dr. Ali Memari – Penn State AE Faculty Kevin Parfitt – Penn State AE Faculty Robert Holland – Penn State AE Faculty All other Penn State AE faculty and staffIndustry Professionals Jeff Antolick – TRC Worldwide Engineering AE message board mentorsDesign Firms Thomas Speer LLC Coreslab Structures DFD CornoyerHedrick Paul Koehler Heliodyne[Hopple‐Final Report]Page 4

Executive SummaryAs climate change continues to become more prevalent in the public eye, it is theresponsibility of every person to make small changes in their life to combat this globalproblem. This senior thesis project is aimed to research and design various elements ofthe building that can be implemented immediately, meaning that all technologies arecurrently used. This report will investigate the use of vegetative roofing, insulatedconcrete sandwich panels, radiant solar collectors, as well as the structural elements asgreen building materials.North Mountain IMS Medical Office Building is a 123,000 square foot medical officebuilding located in Phoenix, Arizona. The building reaches a height of 56’ and consists ofthree supported office floors and a surgical center on the ground floor. The structuralsystem is entirely precast concrete, featuring shear walls as the lateral load resistingsystem.All redesign considerations for this project have the underlying theme ofsustainability. The building was redesigned as ordinary steel moment frames whichgreatly reduced the structure weight. A vegetative roof is proposed as well as increasingthermal efficiency of the building enclosure. Impacts to the mechanical system becauseof these design changes are discussed.The resulting research shows that small changes can have a significant impact onthe overall environmental footprint of the building. However, making these changesrequire certain sacrifices to be made to other aspects of the building design andconstruction.[Hopple‐Final Report]Page 5

North Mountain As Designed ConditionsBuilding and Site OverviewNorth Mountain IMS Medical Office Building is a 123,400 square feet precastconcrete office building located in Phoenix, Arizona. This 10 million design-build projectstarted construction in June of 2007 and was completed February 2008. As part of theNorth Mountain medical complex, the building features a state-of-the-art outpatientdiagnostic imaging center and ambulatory surgery center on the ground floor. The threeremaining floors feature over 92,000 square feet of open, rentable office space. The totalbuilding height is 60 feet, with a mechanical parapet wall that reaches 70 feet aboveground level.[Hopple‐Final Report]Page 6

Typical Framing Plans and DetailsNorth Mountain IMS Office Building floor framing consists of 24” deep, 10’ widedouble tees with a minimum of 3-1/4” concrete topping. The tees are normal-weightconcrete and have a 28-day compressive strength of 6,000 psi. The minimum prestressrelease strength is 4,200 psi. The prestressing strand is 7 wire, ½” diameter 270 ksi lowrelaxation strand. Each strand is pulled to 72.5% capacity, which results in a 30 kip force.The strand is held down at one point in the middle of the tee. Depressed strand providesgreater flexural strength while reducing the stresses in the concrete during prestressrelease. Typical spans are 44’, 48’, and 54’. A typical floor plan is shown below.[Hopple‐Final Report]Page 7

The 24” deep double tees are supported on the interior by 24” deep by 32” wideinverted tee girders. 28-day strength is 7,500 psi and minimum release strength is 3,750psi. Typical inverted tee girders use 22 ½” diameter stand for tensile reinforcement.Span length for a 30’ bay is 28’ due to the columns on each end. Dapped ends on thedouble tees allow the top of the tee to line flush with the top of the girder. The topping isthen poured over the tee and the girder at the same time, interlocking them. Thisconstruction technique is known as emulation. Emulation design creates construction thatis either monolithic at critical joints, or provides connections that act as if they aremonolithic at those locations. This is a great way to connect precast pieces in highseismic zones.Interior spans of inverted tee girders bear on 24” x 24” columns. Concrete strengthis 6,000 psi. There is no need for prestressing strand in columns, because there is nolarge tensile zone. Any tension in the columns is addressed with traditional reinforcingbars. These columns are 56’ tall and arrive on site in one piece. These columns showcaseprecast concrete’s advantages over other structural systems. The columns only need oneconnection, to the foundation. This ease of construction makes North Mountain’s erectionduration much shorter compared to other systems. However, long lead times may be anissue due to cure time and storage at the precast fabrication plant. A typical interiorelevation is shown below to demonstrate the bearing conditions for inverted tee girdersand columns.The exterior walls for North Mountain IMS Office Building fulfill many differentstructural requirements. First, and most importantly, they provide the building enclosure.Second, they support gravity load from double tees. Third, the walls are detailed to[Hopple‐Final Report]Page 8

provide a pleasant architectural aesthetic. Last, but also extremely important, they resistthe lateral forces due to wind and earthquakes. These walls give the structure its rigidityand structural integrity. Without shear walls, a moment-resisting frame system wouldhave to be used. This structure utilizes interior and exterior shear walls. The interiorshear walls are located in the center of the building around the elevator shaft and a stairtower. Shear wall design will be discussed at length in the Lateral Load Resisting Systemsection of this report.Below is an exterior elevation. It is easy to notice the different textures applied tothe exterior of these walls. These finishes are applied when the panels are cast, whichmakes for no further work when they arrive on site. Also, the exterior wall sections depictthe bearing condition for double tees.[Hopple‐Final Report]Page 9

Structural SystemDesign Loads:Live Loads: Roof Live Load .20 psf Floor Live Load .80 psf Stair Live Load 100 psf Partition Live Load 20 psfDead Loads: Superimposed Roof Dead Load .15 psf Superimposed Floor Dead Load 15 psfWind Load: Total Wind Force (North-South Direction) 218 kips Total Wind Force (East-West Direction) . .285 kipsSeismic Load: Design Base Shear . .1627 kipsGravity Loads:The floor live loads for North Mountain are typical office loads. The second, third,and forth floors all feature an open floor plan with no set dimensions for walls or corridors.Because of the open floor plan, the floor live load is 80 psf. By code, corridor loadingabove the first floor is 80 psf. However, 50 psf is the minimum recommended live loadfor office space above the first floor. For design, the corridor value was used as the liveload over the entire floor; it is much easier to assume a uniform load over the entire floorcompared to breaking the loads down between office and corridors. Also, a partition liveload of 20 psf is used over the entire floor.The floor dead load only accounts for 15 psf of superimposed load which includesmechanical, electrical, and pluming equipment. The nature of precast concrete structuresmakes it very simple to calculate the actual weight of the structure; a dead load in poundsper square foot is not needed because each piece of precast is detailed and the exactweight calculated. Tabulated structure weights can be found on pages 12-15 in theAppendix.In Phoenix, there is no snow load. However, a roof live load is still required. Thislive load accounts for potential ponding of rain water and construction loads.Wind Load:Wind Load Factors:Basic Wind Speed, V 90 mph[Hopple‐Final Report]Page 10

Importance Factor, I 1.15Occupancy Category, IVExposure Category, BTopographic Factor, Kzt 1.0Gust Factor, G 0.803 (E-W) 0.814 (N-S)Exposure Classification, EnclosedInternal Pressure Coefficient, GCpi -0.18External Pressure Coefficient, Cp 0.8 (Windward) -0.5 (Leeward) -0.7 (Side)Wind load was not expected to control the lateral design due to the overalldimensions of North Mountain. The building is fairly short and it is not located in a highwind zone. Also, there are no abnormal site features, such as hills or valleys, which wouldincrease the wind speed. Wind load calculations are based on ASCE 7 Method 1. Theresulting calculations gave a base shear value of 218 kips in the North-South direction and285 kips in the East-West direction. Complete wind load calculations are provided in theAppendix on page 16.Seismic Load:Seismic Load Factors:Seismic Response Coefficient, Cs 0.0769Total Dead Load, W 21,153 kipsSpectral Response Accelerations, Ss 0.256, S1 0.075Site Classification, CResponse Accelerations, Sms 0.307, Sm1 0.1285% Damped Design Spectral Response Accelerations, Sds 0.205, Sd1 0.085Approximate Fundamental Period, Ta 0.409 sSeismic loading controls the lateral design. The design base shear for seismic loadsis actually over five times higher than the shear load due to wind. The precast structureis very heavy, which is the main cause for such a high seismic load. The calculated designbase shear is 1627 kips. Complete seismic load calculations can be found on page 19 inthe Appendix.Mechanical SystemNorth Mountain IMS Medical Office Building features a split air conditioning systemfor cooling and a. The split a/c system uses multiple water loop heat pumps and watercooled condensers. The condensers are sized for a summer ambient temperature of 115degrees and a low of 40 degrees. Due to the preliminary nature of the mechanicaldrawings used for this project, these units were not yet specified by the mechanicalengineer.[Hopple‐Final Report]Page 11

Outside air enters the building through one of two air handling units. When cooling,the units cool the air down to 55 degrees. This air is sent throughout the building bymeans of (2) 30”x24” vertical duct runs. These ducts are reduced to 16”x12” horizontalducts to supply each area of the floor. The cooled air is then reheated by hydronic heatpumps based on the needs of the space. Hot water for the heat pumps is supplied by a60 gallon electric water heater with an 85 gallon per minute capacity. Return air iscompletely exhausted; there is no recirculation of return air. The used water is routedback to the electric boiler.[Hopple‐Final Report]Page 12

Project ObjectiveAs climate change continues to become more prevalent in the public eye, it is theresponsibility of every person to make small changes in their life to combat this globalproblem. It is also the responsibility of industry leaders and politicians to make soundchoices concerning the environment. The construction industry is no exception. In theUnited States, 54% of energy consumption is directly or indirectly related to buildings andtheir construction; commercial buildings represent a major share in energy consumption.In the past, this industry has been slow to change as code documents are approved yearsafter they are published. However, technologies needed to stop global climate changecurrently exist. The construction industry should be the leader in the green movement,because public opinion holds “green” as fashionable and we can provide our futuregenerations with sustainable, environmentally friendly buildings.This senior thesis project is aimed to design various elements of the building thatcan be implemented immediately, meaning that all technologies are currently used, toproduce a more sustainable building. This report will investigate the use of green roofing,insulated concrete sandwich panels, radiant solar collectors, as well as the structuralelements as green building materials. When all of these technologies are combined, theresult is a sustainable product which will last for many generations and be an example ofindustry leadership for all parties involved.Structural DepthNorth Mountain’s precast concrete structure is efficient and provides a safeenvironment for all occupants. However, the heavy concrete structure raises the designseismic load to more than five times the wind load. Considering the building’sdimensions, wind load should not control the lateral load resisting system in this region ofthe United States, but reducing the seismic loads could result in a more efficient structure.In general, there are two ways to reduce the seismic load on a building. The first is tochange the lateral load resisting system itself. Different systems have different ResponseModification Factors, R, which is a multiplier used to determine the magnitude of seismicloads. A smaller R value will result in a larger seismic load. The other way to reduce theseismic load is to reduce the weight. This can be accomplished by choosing differentmaterials for the floor framing and lateral load resisting system.This project incorporates both techniques. However, using steel ordinary momentframes will change the R value from 4 to 3.5 resulting in a slightly higher seismic load.However, seismic loads will still be reduced by a dramatic drop in weight. A differentfacade could also be used to reduce weight, but this may drastically alter the exteriorappearance of the building. So, the exterior precast concrete walls will remain. However,[Hopple‐Final Report]Page 13

they will not act as part of the lateral load resisting system. This allows them to be thinwhich, once again, reduces the structure weight.Sustainable Architecture BreadthReducing electricity use and limiting green house gases will help to create a moresustainable Earth. A sustainable building incorporates many different green technologiesthroughout all aspects of construction. For this breadth, a few main components will beinvestigated to produce a more environmentally friendly building. Such components willinclude a vegetative roof and insulation techniques for precast concrete wall panels. Also,the effects of changing the framing system from concrete to steel will be discussed.Mechanical BreadthIn conjunction with sustainable architecture, the means and methods of providingheating and cooling for a building must also be investigated. With the addition of a greenroof and increased exterior insulation, new heating and cooling loads will have to becalculated. Also, by utilizing Phoenix’s 200 plus days of full sunshine a year, energy togenerate hot water can be greatly reduced. A system of panelized radiant solar collectorson the roof will provide hot water for the building’s heating demand. Even though thePhoenix climate does not require a high demand for heating, the goal is to utilize natureas much as possible to provide heating for the building.[Hopple‐Final Report]Page 14

Sustainable Architecture BreadthEnvironmental Effects of Steel vs. Concrete Building n.comWhen considering the environmental effects of buildings, all stages of a building’slife-cycle must be considered. These stages include material extraction andmanufacturing, building construction, building use, building maintenance and buildingend-of-life. Life-cycle assessment (LCA) is commonly used to measure the overallenvironmental impact of buildings. LCA accounts for energy use and emission generationfor every life-cycle stage. Simple LCA is used in this report to compare the environmentalimpacts of the existing precast concrete framing system with the redesigned steel frame.The figure below shows the basic principles of LCA, breaking down the building intophases and measuring each part’s environmental impact. Using this type of approach, itis easy to determine specific areas for improvement.Life-cycle phases of an office building[Hopple‐Final Report]Page 15

The largest difference between concrete and steel frames is noticed in thematerials extraction and manufacturing and building construction phases. The followingsections will discuss and compare the environmental impacts of both concrete and steelrelating to building frames.Material Extraction and ManufacturingSteel is an exceptional performer with respect to recycled content. The amount ofrecycled content in steel products varies over time, both as a function of the cost of steelscrap and its availability. The only manufacturing method used domestically for theproduction of structural shapes contains about 95% recycled content. Since steel is madeto exact specifications, on-site waste is minimized. Steel is the worlds, as well as NorthAmerica’s, most recycled material.Recycling of concrete is a relatively simple process. It involves breaking, removing,and crushing existing concrete into a material with a specified size and quality. The qualityof concrete with recycled concrete aggregates is very dependent on the quality of therecycled material used. Reinforcing steel and other embedded items, if any, must beremoved, and care must be taken to prevent contamination by other materials. Thecrushing characteristics of hardened concrete are similar to those of natural rock and arenot significantly affected by the grade or quality of the original concrete.Fly ash, slag cement, and silica fume are industrial by-products that are used as apartial replacement for portland cement in concrete. These supplementary cementitiousmaterials (SCMs) are pre-consumer materials. If not used in concrete, these materialswould use valuable landfill space. Fly ash is commonly used at replacement levels up to25%; slag cement up to 60%; and silica fume up to 5% to 7%. Because the cementitiouscontent of concrete is about 7 to 15%, these SCMs typically account for only 2% to 8% ofthe overall concrete material in buildings.[Hopple‐Final Report]Page 16

Building ConstructionFor either frame system, materials must beshipped to the site from the fabricator’s shop.North Mountain has a steel fabricator andprecast manufacturer within 20 miles of thesite. This is an important variable to take intoaccount; the trucks used and distance traveledto transport the material can considerablyeffect emissions. Trucks carrying concretepieces can potentially have higher emissionsand lower fuel efficiencies than trucks carryingsteel pieces due to the heavier loads on each truck.Waste and temporary materials used at the fabrication shop are also a largecontributor of negative environmental effects. A few examples are oils and lubricantsused in steel shops and wood forms used in precast concrete production. Precastconcrete, however, has many advantages over cast-in-place concrete. Since each precastmanufacturer produces standard size pieces, formwork is typically used more than once.Also, controlled shop settings reduce the amount of waste concrete used. Steel shapesare manufactured to exact specifications, so steel waste is limited.Building Use and MaintenanceBuilding use and maintenance includes all impacts of functions, renovations,materials and related activities to the use phase of a building. This phase is the mostenergy intensive within LCA; it includes all the energy required to heat, cool and powerthe building. Energy consumption during the use phase is typically the main topic ofdiscussion when considering sustainable design. However, the structure represents littleenvironmental impact during this phase. For a typical office building, such as NorthMountain with a 50 year lifespan, the building use and building maintenance phase iscomparable for either a concrete or steel frame. The best way to limit negativeenvironmental effects caused by the building frame during this phase is to ensure efficientand practical construction practices.[Hopple‐Final Report]Page 17

Building End-of-lifeThe end-of-life phase includes demolition of the building and removal of debris.Typically, concrete buildings take longer to demolish than steel buildings. Also concreteframes are much heavier than steel frames which will require more trucks to removedebris off site. Nearly 100% of structural steel is recycled into new steel products at theend of their useful life. Concrete is a relatively heavy construction material and isfrequently recycled into aggregate for road bases or construction fill. Concrete can beespecially difficult to recycle because all other materials must be removed, such as rebar.Once separated, rebar can be recycled. Concrete frames have more embodied energy due to the use of temporarymaterials such as formwork and extra transportation impacts due to its larger mass.However, construction of steel frames produces more volatile organic compounds (VOCs)and heavy metal emissions due to touch cutting and welding. Referring to page 37 in theAppendix, typical construction process diagrams of steel and concrete buildings showwhere waste and various emissions are generated. Studying these diagrams proves to beinconclusive when trying to determine the worst environmental offender. There is not aprominent difference between concrete and steel frames. Also, building frameconstruction only represents up to 10% of energy use during a building’s life cycle.Relating LCA to North Mountain will create more efficient building structure andsystems design. In terms of this project, many sustainable items have been implementedin the redesign. A green roof will significantly reduce roof maintenance costs and energyuse for heating and cooling systems. Insulated concrete panels will further reduce energyuse. Including specifications to include recycled content into construction materials willreduce manufacturing emissions. Since the redesigned structure will feature mostly steeland concrete produced in fabrication shops, on site construction waste will be kept to aminimum. The structural frame for North Mountain, whether steel or concrete, will nothave near the environmental impact as the mechanical and electrical systems.[Hopple‐Final Report]Page 18

Green RoofGreen roofs provide many benefits for the environment, building occupants, andbuilding owners. These advantages range from ecological to aesthetic to economic. Theecological benefits stem from replacing an unnatural surface with a mini ecosystem. Also,the green roof replaces the land that the building footprint occupies. Aesthetically, agreen roof is a drastic improvement from an ordinary roofing system. Adding a green roofwill add another level of aesthetic interest to a building. Economic benefits are notrealized until the long term. Green roof installation is more expensive than a traditionalsystem, but investing the extra initial capital can return by reduced maintenance costsand energy savings.(Arizona green roofs, from left: Riverfront Residence, Yazzie Residence, Optima Camel View Village)Green roofs can provide an inviting outdoor space while serving as a functional wayto limit the heat island effect, control water runoff, and help to reduce energyrequirements for the building. The proposed green roof for North Mountain will fulfill twoof the above beneficial aspects; it will reduce both the heat island effect and buildingenergy consumption.According to the National Weather Service, Phoenix averaged 6.7 days of 110degree heat a year in the 1950’s. Now, that number averages 21.9 days. Unfortunately,this extreme heat does not dissipate at night; it is stored in the cities’ buildings and pavedsurfaces. Outlining rural areas of Phoenix have an average night time low that is 14degrees cooler than the city. Higher night time temperatures result in more energy andwater use. This was the main factor when choosing to add a green roof to NorthMountain.Evaluating a green roof’s insulation properties and determining exactly how muchenergy can be saved is a difficult task. Depending on water within the soil, the R-valuewill change dramatically. However, since there is little rain in Phoenix, the R-value of theroof will remain fairly constant. This R-value is not the most beneficial thermal aspect ofa green roof. Since the green roof will have vegetation, the sun’s rays are reflected awayfrom the roof. This will reduce the actual temperature on the roof. Also, when it doesrain, the process of evaporation will dissipate heat. Even though an exact R-value cannotbe determined, there are many ways that the green roof will reduce stored thermalenergy. These energy saving aspects will be discussed further in the mechanical breadth.[Hopple‐Final Report]Page 19

Selecting vegetation for a green roof in Phoenix Arizona is a challenging task. It isso challenging, in fact, that some landscape architects consider such informationproprietary. The main challenges are the desert heat and little rainfall. However, manynative plants will thrive in this environment. Most desert plants have long root systems.The plants use the long roots to search for water deep below the surface. Here in theNortheast, it is common to have a growing medium of only a few inches. In the Arizonasun, this is impossible without extensive irrigation. Irrigation should be avoided in mostcases; the plants used for this project do not require irrigation. Water in this area isscarce and should be used only for necessity.Using a variety of flowering plants and shrubs, the growing medium should be atleast 10 inches deep for this area. Twelve inches ensures that root systems have ampleroom to develop. If large shrubs or small trees are desired, a soil depth of 24 inches isrecommended. However, using this amount of soil can strain the structural system.Larger gravity beams are needed to provide the strength required due to the extra deadload. Also, placing this load on the roof causes a significant earthquake load to be appliedat that story. As a goal of this project, lateral loads are to be kept to a minimum. Effectsof this additional weight will be addressed in the structural depth portion of this report.For North Mountain, a soil depth of 10 inches was chosen. With this depth, onlysmall shrubs can be used. Again, no irrigation is necessary with the vegetation selected.Using many online landscaping guides for the Phoenix region, the following plants wereselected.Trailing Rosemary: As one of the best and toughestplants for arid growing zones, trailing rosemary does well in pooror shallow soils. It tolerates great heat and blazing sun as wellas cold climates. Pale flowers appear along branches in springand throughout the year. The low-growing form is used as aground cover. The upright form makes a nice shrub or hedge.Grows to 2 feet high and spreads 3 to 6 feet or wider.(www.horticultureunlimited.com)Damianita: This ground cover is a star performer in thearid Southwest. Damianita has a long blooming season andfragrant foliage. Golden yellow, daisy-like flowers are small about 1/2 inch across. Bright green, needle-like leaves create anice contrast to the flowers. This plant has a long bloom period,but flowers are most profuse in the spring and fall. Damianitagrows at a moderate rate to 2 feet high and 2 feet l Report]Page 20

Prickly Pear: Easily grown in dry, sandy or gravelly,well-drained soils in full sun. May be grown in clay soils as longas drainage is good and soils do not remain wet. Plants oftenspread in the wild to form colonies as pads break off and rootnearby. (www.mobog.org)Hedgehog Cactus: A small barrel-shaped cactus.Flowers are scarlet red, with many petals, and are cup-shaped.The flowers are one to two inches long and grow below thestem's apex. Flowers bloom April through June, from low tohigher elevations. This is the first cactus to bloom in the spring.The flowers bloom three to five days. (www.desertusa.com)[Hopple‐Final Report]Page 21

Precast Concrete Sandwich PanelsArchitectural precast cladding provides an efficient building enclosure while offeringa variety of finishes that can provide almost any desired aesthetic. Since the product ismanufactured in a factory setting, there is high flexibility of architectural finishes.Manufactures must satisfy strict dimensional tolerances and offer superior performance.These panels are thermally efficient and use a minimal amount of material.Examples of Architectural Precast (from left): Gateprecast.com, acps.com, Ravacast.comPrecast concrete sandwich panels were chosen as the building envelope for thisredesign project mainly to ensure that the architectural aesthetic of the new systemresembled the architect’s original design. This was achieved by casting the panels withthe same dimensions as

North Mountain IMS Medical Office Building is a 123,400 square feet precast concrete office building located in Phoenix, Arizona. This 10 million design-build project started construction in June of 2007 and was completed February 2008. As part of the North Mountain medical complex, the building features a state-of-the-art outpatient