Concrete Masonry Designs
Concrete Masonry Enhances
Modern School Design
Superior Fire, Seismic, Wind and Blast Protection Combine with Flexibility, Value
Buildings serving school systems are required to have long lifespans — 50 years or more in many states — and they need to withstand heavy use. With their resistance to fire, wind, seismic events, explosions and other extreme loads — concrete masonry products are strong choices for school construction. Concrete masonry also provides mold resistance, favorable acoustical sound control, and high thermal mass, reducing energy use.
Concrete masonry products and systems offer competitive cost, especially when factoring in the life of a structure and lower maintenance expenses over time. In addition, these building products offer a great deal of design flexibility for attractive, efficient and environmentally sustainable schools. Modern architectural concrete masonry units are produced in a wide range of shapes, sizes, colors and textures, so new school construction can reflect a range of community values, from boldly innovative designs to more traditional looks that echo the colors and accents of existing structures.
When used in schools, concrete masonry can provide the loadbearing walls as well as the building façade. This means architects have a serviceable material option that also can become a prominent design element.
Versatile and code compliant
Many state education departments set standards for public school design and costs, and other local government codes may add even more stringent requirements for school building construction. These standards strive to ensure quality, durability and proper return on investment for taxpayers. Some states and communities are joining in ambitious efforts like the Collaborative for High Performance Schools, a national movement that strives to improve student performance by building the best possible schools, or the Green Schools Alliance, an international drive to help schools become more environmentally sustainable learning environments. With either initiative, concrete masonry products offer the flexibility and sustainability to fit the need.
Concrete Masonry and School Costs
Every dollar counts in elementary and secondary school construction. So, in most public schools systems, value and return on investment are key concerns when it’s time to build a new school. This is especially true in fast-growing communities that may need to build schools quickly to keep up with an influx of new residents.
Fire Resistance
Choosing concrete masonry rewards a school district with lifesaving fire-resistant qualities. Concrete block, also known as concrete masonry units, or CMUs, don’t burn, melt or warp when exposed to flames. And, after being doused by water from a fire hose, block can be cleaned and repainted, while competing materials usually need replacement. Concrete masonry’s inherent fire-resistive capabilities and structural characteristics help to meet school construction requirements and comply with architectural design standards.
With concrete masonry envelopes and concrete masonry interior walls, school classrooms and other campus buildings are fire-safe. CMU party walls—the interior walls between rooms and school usage areas—create a containment system, known as compartmentation, which will limit the effects of fire and smoke damage in a fire event.
The passive fire protection offered by concrete masonry walls can also provide a refuge area when evacuation is not immediately possible. Floor and wall elements forming the boundaries of each compartment should have a minimum fire-resistance rating of two hours. Openings through compartment boundaries should be protected. Compartments also inhibit the spread of toxic fumes and smoke to adjacent areas of a building. CMU walls are a fire safety feature that protects occupants and avoids physical damage to the building.
The fire resistance rating of concrete masonry, as explained in technical reference documents provided by the National Concrete Masonry Association, is typically governed by heat transmission criteria. From the standpoint of life safety (particularly for fire fighters) and salvageability, this failure mode is certainly preferable to a structural collapse, characteristic of many other building materials.
To provide the best protection and greatest opportunity for occupants to escape a fire, NCMA recommends that codes for buildings require a balanced design made up of three key elements: fire detection, fire suppression and fire containment. Fire detection includes the installation of smoke detectors and fire alarms. Active fire suppression includes the use of sprinkler systems. Fire containment includes fire barriers, fire-rated assemblies and exterior walls built of substantial, noncombustible, fire-resistant materials such as concrete masonry.
Seismic and blast resistance
Seismic design and blast resistance sometimes go hand-in-hand, and today’s school designers must take care to account for the varying probability of such events. As part of the seismic design, (again found in technical reference documents provided by the National Concrete Masonry Association), schools three stories or higher should be designed to factor in protection against progressive collapse. Standoff distance is one factor, but the buildings need to provide structural system continuity, according to the earthquake standards, and must offer redundancy among structural components that will aid in limiting collapse under the extreme loading events of an earthquake.
Concrete masonry is particularly good at avoiding collapse when shearwalls are all reinforced masonry set perpendicular to the perimeter. Resistance to progressive collapse can be provided by reinforcing adjacent and perpendicular walls with extra heavy reinforcement.
Architects designing buildings on military installations have learned lessons that can be applied to schools. For example, the structural reinforcement requirements of the seismic design of the concrete masonry offer substantial benefits, including blast resistance, over typical metal studs.
Although the intent is to keep a blast threat as far away from occupied buildings as possible, that isn’t always feasible. In some cases all façades of the building cannot be set a far enough distance from the parking and roadways. Strategies to overcome this issue include additional reinforcement in the walls—already necessary for adequate seismic design.
The selection of concrete masonry for envelope and structural systems can provide visual cohesiveness, and reinforced masonry helps keep costs down, meets seismic requirements and blast resistance while minimizing the land area needed as a protective buffer. As a result, schools built with these features can look forward to 50 good years in these buildings.
Concrete masonry offers other school design advantages:
- Energy Savings: Concrete masonry contributes to a building’s energy efficiency in a number of ways. Concrete masonry’s thermal mass evens out temperature swings, reducing energy consumption and costs over other materials. Steel walls, for example, are less effective because steel is a prime conductor of heat and cold. Masonry construction’s thermal storage properties can reduce heating and cooling loads and allow for smaller, more efficient HVAC equipment.
- Low Maintenance: Repairs with concrete masonry are infrequent because block resists marring, gouging and scratching much better than competing materials, resulting in lower maintenance costs. In addition to these economies, block helps take the pressure off the facility’s maintenance department, another bonus.
- Loadbearing Economy: With loadbearing masonry construction, designers can combine a school building’s structural wall system and exterior into one unit, eliminating redundant support systems, thus speeding construction and reducing costs.
- Acoustics: With block partition walls, the mass dampens sound, sheltering classrooms from distracting noise. And block’s sound-dampening qualities are more consistent and reliable than those of competing materials.
Overall, schools are subjected to the scrutiny of the taxpaying public, when it’s a public school system, or to patrons and benefactors of private schools. Done well, concrete masonry school design and construction results in attractive and cost-effective schools that broadcast a positive message that quality matters and financial resources are being wisely spent.
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SOURCES
http://www.masonrymagazine.com/4-04/csibenefits.html
