Statistics | micaheldemire

General Building Data

•   Building Name: The Gibson Building
•   Location and Site: Northern Virginia
•   Building Occupant Name: Multiple
•   Occupancy or Function Type: Mixed Use building for Higher Education and Leasable Office Space
•   Size: 170,156.74 sf (w/o garage) and 286,915.42 sf (w/ garage)
•   Building Height: 135’
•   Number of Stories: 9 Levels Above Grade/3 Levels of Parking Below Grade

Project Team and Means

•   Owner: The Gibson Family
•   Architect: BINI
•   Construction Manager: Builder Construction
•   Civil Consultant: Survey Engineers
•   Landscape Consultant: Field Design
•   Structural Consultant: Structural Beam Inc.
•   M.E.P. Consultant: M.E.P. Layout
•   Vertical Transportation Consultant: Vert. Tech
•   Irrigation Consultant: WATER
•   Construction Dates: August 31st, 2015 - June 9th, 2017
•   Overall Building Construction Cost: $39 million
•   Project Delivery Method: GMP Hard bid

Architecture

Quick Background

The Gibson Building is part of the redevelopment of a previously occupied area by The Gibson Family. The site will encompass two new, but separate, structures that will take place of a previously existing one. The design of The Gibson Building is intended to reach LEED Gold through design and construction methods. These methods include salvaging material from the old building and incorporating them into the project, which doubles as achieving the historical requirements of the city. Also, there will be an improved Metro Stop at the site location to make public commute more attractive that will include bicycle parking.

Enclousures

The exterior façade of The Gibson Building follows the typical architecture found in the area with the use of glass and another solid façade material. The North façade of the building consist of precast architectural concrete panels with embedded terracotta inlay and glass canopies at all entrances. Running along the length of the building is a different color precast architectural concrete that marks the location of each floor level. The punched windows on the North Façade are glazed aluminum window walls with 1” insulated glass spandrel supported by a metal back pan and metal panel spandrel. Also on the North façade of the building are metal louvers used for air circulatory purposes.

The South building façade has the same makeup as the North side of the building except that there is a decorative perforated metal screen that runs upwards from the 3rd floor of the building to the penthouse roof. The West façade of the building has the same makeup as the North and South sides of the building excluding the decorative metal panels and perforated screens. It also has less of a solid surface and uses more glass to allow more light to penetrate the building. The East façade of the building is the façade that stands out the most. The entire façade is a curtain wall system that runs from the ground floor to the top of the 9th and is made up of the same glass placed on all other sides of the building. On the right side of the East façade, precast architectural concrete flows the full height of the building, starting from the ground floor and ending at the roof top.

To help reach its goal of LEED Gold, The Gibson Building has a green roof. The green roof consist stacked layers of “growing media”, filter fabric, drainage board, root stop, roof insulation, and hot fluid applied roofing which all sits on top of a cast on place concrete structural slab. The parts of the roof that aren’t a part of the green roof system consists of stacked layers of gravel, a double filter fabric layer, roof insulation, protection board, and hot fluid applied roofing which also sits on top of a cast in place concrete structural slab.

Zoning and National Codes

The project falls within Zoning C-0-2.5, which for Arlington, VA means it falls under a “mixed use district” zone. In order for The Gibson Building to be constructed and done so in a proper manner, it had to comply with the law of the land and zoning requirements. To achieve this, BINI and their consultants had to design the building with the following codes in mind with modifications of some:

•   2009 International Building Code…………………………....................................................................................................…………………………………(Building and Structural)
•   2009 Virginia Statewide Building Code…………..................................................................................................………………………………..(Building, Structural, and Fire)
•   2005 ASCE 7……………………………………………….......................................................................................................………………………………………………………………..(Structural)
•   2009 International Fire Code…………………………………………………………….......................................................................................................………………………………..…(Fire)
•   2009 Arlington County Code Chapter 8.1 Fire Prevention Code…………………..................................................................................................………………………...(Fire)
•   2009 International Mechanical Code……………………………………………………….....................................................................................................………………..(Mechanical)
•   2009 International Plumbing Code………………………………………………………......................................................................................................…………………..….(Plumbing)
•   2009 International Fuel Gas Code…………………………………………….....................................................................................................……………………………………….…..(Gas)
•   2008 NFPA 70 National Electric Code…………………………………………...................................................................................................…………………………………(Electrical)
•   2007 NFPA 72 National Fire Alarm Code………………………………...................................................................................................……………………………………(Fire Alarms)
•   2007 NFPA 13 Standard For The Installation Of Sprinkler Systems…….................................................................................................…………………………(Sprinklers)
•   2009 International Energy Conservation Code………………………………….................................................................................................…………(Energy Conservation)
•   2007 ASHRAE 90.1………………………………………………………………………….....................................................................................................…………..(Energy Conservation)
•   Americans With Disabilities ACT 2010………………………………………….....................................................................................................…………………………..(Accessibility)
•   2003 ICC/ANSI 117.1……………………………………………………………………….........................................................................................................……………………….(Accessibility)

Primary Engineering Systems

Construction

This project is being delivered using a Design-Bid-Build method. The Gibson Building is being built directly next to another project that the owner is involved in. Fortunately enough for the CM company they won the bid of both jobs. As a result, the excavation for both buildings were dug as one big hole but the construction of both project are being conducted completely separately.

To catch potential issues during construction and to help with coordination between subcontractors, NAVISWORKS 3D was relied on heavily for this project. A completed Revit model was imported into NAVISWORKS in order to generate the proper schedule to complete construction on time. The construction of The Gibson Building was started August 31st, 2015 and is set to end June 9th, 2017.

Electrical

Power from the city’s grid enters the building into the main electrical room located on the level 1 parking deck. The power comes into a 277/480 V switchboard at 4,000 A. The switch board, which is labeled switchboard 1, then goes on to supply power to the rest of the building. In case of an emergency there is a 277/480 V, 3phase, 600 KW backup diesel fuel generator to provide power to all emergency lighting and other necessary space.

Lighting

The lighting for the building was designed to be the most cost effective. Since a lot of the building space is intended to be leased to different tenants, the lighting for the building consist temporary lighting. Lighting fixtures in future tenant spaces consist of 3’ to 4’ long F032T8/830/ECO T8 fluorescent lights that provide the bare minimum luminance required by code. This was done so that future tenants have the ability to layout the office the way they want to. All permeant core spaces and academic spaces consist of 3000K LED lights to provide better lighting for these areas.

Mechanical

The Gibson Building has a typical commercial building set up. Located on the penthouse roof are two chillers and one cooling tower that make up the cooling system for the building. The chillers and cooling towers send cold water to air handling units located on each floor that is used to cool the building off. Due to amount of BTUs expected to be given off by the occupants of the building and the equipment that they will use, VAV boxes are being used to heat the building on each level. Each level in the parking garage maintains the proper indoor air quality with the use of air intake and exhaust shafts. These shafts supply and exhaust air through the area using fans that suck air from the outside through louvers located on the ground floor.

Structural

The Gibson Building has a Cast-In-Place post tension concrete structural system designed using the 2009 IBC. The foundations system of this structure utilizes 40 ksf spread footings except in “soft” areas where 30 ksf spread footings are used. There is also a 12” 4 ksi foundation wall that sits on a 2’ wide continuous footing around the perimeter of the building. Footings sit on top of disintegrated rock about 2’ below the building structure and range from 4’ to 9’ in width with thickness of 20” to 40”. Sitting on top of these footings are 16x24 and 24x16 8 ksi Cast-In-Place concrete columns that extend up through three levels of parking to the top roof framing structure. At parking level 1, most columns slope to line up with the column layout of the above grade structure. As you travel up the height of the building concrete columns change strength from 8 ksi to 6ksi at the 4th floor of the building and from 6 ksi to 5 ksi at the 8th floor of the building.

The ground floor slab on grade, as well as all other floors, are one-way slabs with varying structural slab thickness ranging from 8” to 12”. Varying slab thickness both around columns and other locations in the slab help to deal with punching shear, slab deflection, amount of rebar used, and other problems. Structural slab on grade has a strength of 4.5 ksi where as other slabs have a strength of 5ksi. Since there is no cross bracing or shear walls in the building due to space limitations, to take on lateral loads, the structural diaphragm (slab) was design to take on these forces.

The structural slab on each floor absorbs the lateral loads on the building and kick those forces out to post tension and non-post tension beams located on every floor. There is really no typical non-post tension beam size but come as small as an 8”x24” (wxd) and as large as a 24”x94” (wxd) with #5 to #10 rebar reinforcement. Post tension beams can reach width up to 84” and depth up to 22” with tensile force up to 1200 kips in them.