PE PDH
PDH Online

Tornado Risks, Shelter and Recommendations


Quiz Questions

1.Can a building survive a tornado?
Yes, High-wind shelters can be designed and constructed to protect occupants from winds and wind borne debris associated with all tornadoes (EF0–EF5).
No, no building can be built to survive tornadoes.
2. A shelter is typically an interior room, space within a building, or an entirely separate building, designed and constructed to protect its occupants from tornadoes or hurricanes. Shelters are intended to provide protection against both wind forces and the impact of wind borne debris. The level of occupant protection provided by a space specifically designed as a shelter is intended to be much greater than the protection provided by buildings that comply with the minimum requirements of building codes. The model building codes do not provide design and construction criteria for life safety for sheltering nor do they provide design criteria for tornadoes.
True
False
3.There are two general types of residential shelters: in-residence shelters and shelters located adjacent to, or near, a residence. An in-residence shelter, also called a "safe room", is a small, specially designed ("hardened") room, such as a bathroom or closet that is intended to provide a place of refuge for the people who live in the house. An external residential shelter is similar in function and design, but it is a separate structure installed outside the house, either above or below ground.
True
False
4. A community shelter is intended to provide protection for a large number of people, anywhere from approximately 12 to as many as several hundred individuals. These shelters include not only public shelters but private shelters for businesses and other organizations.
True
False
5.Buildings are designed to withstand a certain wind speed (termed "design [basic] wind speed") based on historic wind speeds documented for different areas of the country. The highest design wind speed used in conventional construction is near the coastal areas of the Atlantic and Gulf Coasts and is in the range of 140–150 mph, 3-second gust in most locations. By contrast, the design wind speed recommended by FEMA for shelters in these same areas is in the range of 200–250 mph, 3-second gust; this design wind speed is intended to provide "near-absolute protection."
True
False
6.The picture in page 14 shows a shelter under construction inside a residence with steel reinforced and fully grouted CMU surrounding the shelter space, in New Smyrna Beach Florida.
True
False
7.Pre-Code Manufactured Homes refers to homes built before June 15, 1976, when the Department of Housing and Urban Development (HUD) began regulating construction. Prior to 1976, manufactured housing was essentially unregulated and wide variations in construction quality and strength existed. Precode manufactured homes were often called trailers or mobile homes because they were intended to be moved from place to place.
True
False
8.Early Code Manufactured Homes are homes built after June 15, 1976 (and before July 13, 1994) when the Manufactured Home Construction and Safety Standards (MHCSS), developed by HUD, first went into effect. After 1976, homes became known as "manufactured housing." The MHCSS specified minimum wind pressures that manufactured homes must be designed to resist. It also contained general criteria for anchoring homes to resist wind forces. The wind pressures required by the MHCSS correspond to a sustained wind speed of around 70 miles per hour (mph) in an Exposure C area. This is approximately equivalent to 85 mph peak gust winds.
True
False
9.Hurricane Andrew destroyed numerous manufactured homes in 1992. In response to this damage, the MHCSS standards were strengthened on July 13, 1994. The strengthened standards apply to homes placed in higher wind speed areas. These 1994 revisions, which remain in effect today, established three types of homes: HUD Zone I, HUD Zone II, and HUD Zone III homes.
True
False
10.
  • HUD Zone I homes are those homes designed to the original 1976 standards.
  • HUD Zone II homes are designed to resist sustained wind speeds of 100 mph (equivalent to approximately 120 mph peak gust winds).
  • HUD Zone III homes are designed to resist a sustained wind speed of 110 mph (equivalent to approximately 130 mph peak gust winds).

NOTE: "Sustained" wind speeds are approximately fastest mile wind speeds; "gust" wind speeds are approximately 3-second gusts wind speeds.

True
False
11.Anchorage failures occur when the home is lifted, slid, or rolled off its foundation. An anchorage failure can destroy a home even when there is no direct wind damage to the home itself.
True
False
12.Anchorage failures typically result from:

  • Too few anchors used to secure the home
  • Improper anchors selected for the soils present on site

Corroded anchors or anchor straps

True
False
13.In page 27, the difference between anchorage for homes in zone I and Zone II & III are:
There is no difference between the anchorages.
Zone II & Zone III have extra vertical, side tie downs, as seen on the schematic.
14.Page 28 shows some examples of anchorage and support failures.
True
False