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Recommendations and Technical Guidelines for Midwest Tornadoes


Quiz Questions

1.Which one of the followings did the BPAT (Building performance assessment team) recommended for reducing future tornado damage to property and providing personal protection.
Proper construction techniques and materials must be incorporated into the construction of residential buildings to reduce their vulnerability to damage during extreme wind events. Existing construction techniques proven to minimize damage in wind-prone areas are not always being utilized in areas that are subject to tornadoes.
Construction should be regulated and inspected to ensure that residential buildings meet the most current building code requirements, including those regarding structural seismic issues.
For engineered buildings, the engineer should review connections to ensure adequate capacity for moderate to severe uplift and lateral loads that may be in excess of loads based on the building codes currently in effect.
Cities and appropriate local governments should adopt the 1997 UBC or 1996 NBC as the model building codes.
Cities and appropriate local governments not already using the 1995 CABO One- and Two-Family Dwelling Code should do so immediately.
The International Building Code (IBC) and the International Residential Code (IRC) should be adopted upon their release in 2000.
Shelters are the best means of providing near absolute protection for individuals who are attempting to take refuge during a tornado.
All shelters should be designed and constructed in accordance with either FEMA 320 or The National Performance Criteria for Tornado Shelters.
All of the above
2. According to the tornado classification and pictures in page 28, in a F-3 tornado, roofs and some walls torn from structures, some small buildings are destroyed, non-reinforced masonry buildings are destroyed, most trees in forest are uprooted.
True
False
3.Figure 3-3 is an example of
A load uplift tornado damage to a house
A load inward tornado damage to a house
4. Engineered shelters not only provide the best protection against loss of life for individuals subjected to a tornado, but also furnish the only protection reliably capable of providing survival.
True
False
5.Figure 6-1 shows:
An above ground engineered shelter that was struck by a strong tornado in Oklahoma
A masonry home during construction
None of the above
6.In Figure 6-15 Ballast roof covering on a community shelter in Wichita, Kansas was a potential source of deadly windborne missiles to those seeking to access the shelter.
True
False
7.A general recommendation for buildings that could be in a tornado path would be:

  1. Design buildings to the most current building codes and standards that provide greater protection against moderate tornado-generated winds.
  2. Provide safe refuge in the event of a severe or violent wind storm or tornado in the form of engineered shelters.
Ture
False
8.Sheathing at areas of discontinuity should be fastened in a manner that will resist uplift forces with a factor of safety over the design wind pressure stipulated in applicable building codes and standards. Some current building codes reflect an increased fastener size intended to address high wind areas.
Ture
False
9.The masonry industry should consider re-evaluating attachment criteria of masonry, specifically regarding product usage. Greater emphasis should be given to code compliance for the bond between the mortar and brick tie, the mortar and the brick, and to the spacing of brick ties.
True
False
10. Garage doors are an extremely important residential building component. Failure of these doors led to catastrophic progressive failures of primary structural systems that could have been avoided. New garage doors should be installed with improved resistance to moderately high wind loads. Retrofits should be made to improve the wind resistance of existing garage doors, specifically double-wide garage doors. These retrofits and new doors may reduce the roof and wall damage that was observed in homes that experienced garage door failures.
Ture
False
11. The Federal Government (HUD) should review its standards and enforcement program in an effort to improve the performance of manufactured homes in moderately high wind events, such as in inflow areas of severe to violent tornadoes and the tracks of moderate tornadoes. Specifically, the capacity of anchoring and strapping equipment and systems needs to be evaluated to eliminate the discontinuity between the Federal standard and the State and local installation and enforcement process.
True
False
12. Consideration should be given to permanently connecting the manufactured home unit to its foundation. The BPAT concluded that newer manufactured homes on permanent foundations performed as well as conventional stick built homes in resisting lateral wind loads, as long as there was an adequate connection of the chassis and perimeter joists to the permanent foundation.
True
False
13. For non-residential buildings, the BPAT recommends using threaded fasteners to attach joists and metal decking to supporting frames and walls. In many of the roof system failures observed by the BPAT, current welding practices were insufficient in carrying loads and weld failures were common.
True
False
14. To reduce the number of missiles generated from roofs on essential facilities (e.g., hospitals) and buildings such as schools, aggregate ballast and paver surfacing should not be used. Enhanced wind design for the roof covering on essential facilities should be considered for those facilities located in tornado-prone areas.
True
False
15. When wood construction is not utilized, reinforced concrete and partially reinforced masonry with adequate ties to foundations and roofs should be used in areas with a high probability of being hit by a tornado. Ties between concrete and other materials should be made with drilled-in fasteners or cast-in-place fasteners.
True
False
16. Diaphragm action to resist shear forces must be maintained and reinforcement must be properly placed in concrete and masonry walls to reduce the possibility of collapse. Masonry walls should be engineered and constructed to support the specific architecture of the building.
True
False
17.Precast concrete buildings should have anchors to prevent the uplift of hollow core planks and other precast elements. Better performance would have been obtained if drilled-in expansion anchors or through-bolts had been used to attach the walls to the floors. Use of powder-driven anchors to attach bottom plates of walls to concrete should be avoided unless they are very closely spaced to achieve sufficient pull-out resistance.
True
False
18.Undamaged sections of brick veneer walls should be inspected, and where they can be deflected or pulled off, the air space behind the veneer should be grouted and reinforced, or be replaced.
True
False
19. A brick veneer wall system should be designed as a "stand alone" system. Current construction practices for brick veneer need to be improved so that a flexible connection between the framed wall and the veneer does not result.
True
False
20. It may be necessary to fasten brick ties with ring or screw-shank nails to prevent nail pull-out at brick ties.
True
False
21. Architectural features should be appropriately designed, manufactured, and installed to minimize the creation of windborne debris. To accomplish this, the local community may want to further regulate these features to ensure code compliance.
True
False
22. The installation of laminated glass in essential facilities should be considered because of the substantial protection that it offers from modest-energy missiles. Testing should be conducted in accordance with ASTME 1886, based on load criteria given in SBCCI STD 12.
True
False

To better address structural and architectural issues related to moderately high wind events, State and local governments should consider adopting the most current edition of their model building code. Other recommendations related to building codes and enforcement are provided below:

23. Cities and appropriate local governments should adopt the 1997 UBC or the 1996 NBC as the model building codes. Amendments that require calculation of wind loads via ASCE 7-95 or the new ASCE 7-98 should also be adopted. Currently, the 1997 UBC & 1996 NBC reference ACSE 7-95, but allow their own UBC/NBC methods to be used; it is important to note that wind calculations from these methods will result in lower loads than calculations from ASCE 7-95 or 7-98. For buildings other than one or two family dwellings, state and local governments should adopt the latest codes that specify the most current engineering standards for wind loads for the design of structural components and cladding.
True
False
24.Governments using a previous version of the 1995 CABO One- and Two-Family Dwelling Code should update to the 1995 version immediately. This will provide some guidance for designing for moderate wind loads.
True
False
25.The International Building Code (IBC) and the International Residential Code (IRC) should be adopted upon their release in 2000. Although these codes do not directly address the threat of tornadoes, they address wind load issues using ASCE 7-98 for both non-residential and residential construction, respectively. Use of codes based on ASCE 7-98 will reduce future losses from moderately high wind loads.
True
False
26. Greater emphasis should be given to code compliance, particularly for wall and roof covering wind loads and resistance. Homebuilders and code enforcement agencies should consider developing an active education and outreach program with contractors to emphasize the importance of code compliance for wind resistance.
True
False
27. State and local governments should consider creating a task force with the different building code groups and construction industry groups to determine if basic wind speed classifications should be reconsidered for tornado-prone areas.
True
False