Elena's track is shown in Figure 11.20 (and recall the satellite image of Elena in Figure 11.15). Sparks used the best available wind-tunnel pressure coefficients for the roof of a single-story, 80 ft by 80 ft building in a suburban area to estimate the mean recurrence intervals for wind pressure in excess of those prescribed by the Standard Building Code between 1974 and 1986 (SBC2). Washover was minor and local from Elena and one new tidal pass was generated on … The Payless Shoe Source in Pascagoula may have been designed professionally, but it was probably below the size where this would have been required by the code. Also, a large portion of a wood roof deck was removed from the most windward building (Figure 4-44) in an area with a large overhang. A second form of anchorage mentioned in the code that uses a bond beam would prove satisfactory only if the bond beam were properly tied to the foundation by vertical wall reinforcement. In one location where the wall was not protected by the canopy, the bar joists failed, and the wall, lacking top support, collapsed. Also, the performance of preengineered churches was satisfactory (Figure 4-25). The shortcomings in assessing design wind pressures are best illustrated by reference to the design pressures that would have been used in the design of buildings that sustained the most serious damage in Elena—namely, flat-roofed buildings 10 to 20 ft high. Tens of thousands of preengineered metal buildings have been constructed over the past two decades in the areas affected by Elena (1985), Frederic (1979), and Camille (1969). Following Hurricane. Churches generally favor steep-pitched roofs that experience low uplift forces except when the wind is blowing over the gable end. Hurricane Elena was a … In exposed locations during Hurricane Elena, the suction on the roofing membranes near the corners probably exceeded the tested capacity of Class 30 and 60 roofs. Figure 4-31 Collapsed roadside shelter at rest area on Interstate Highway 10 All units failed. Hurricane Claudette caused minimal impact in the Lesser Antilles. See Hurricane … When the 1974 revisions to the 1973 code were introduced (SBCCI, 1974) to make use of this type of wind-speed map, a probability of exceedance in a given year of 0.01 was chosen, commonly known as the 100-year fastest-mile wind speed. (Courtesy of The Sun/The Daily Herald, Biloxi.). HURRICANE ELENA DAMAGE SURVEY: SEPTEMBER 2, 1985 by Timothy P. Marshall (September 1985) We have completed a damage investigation of Gulf Coast areas struck by Hurricane Elena. Two preengineered metal buildings were sited near the bridge connecting. Insured damage from Elena ranked as the fourth largest on record with a total of $543 Millionreported by the American Insurance Services Group. Elena was the first major hurricane of the 1985 season and it's unusual path included a loop and went back and fourth along the Florida panhandle as a category 3 storm heavily damaging the Apalachicola, FL oyster industry. Hurricane Elena impacted the coasts of the Florida Panhandle and Alabama too. An analysis of the wind data from the Dauphin Island Bridge by Reinhold and Mehta (1981) determined that the fastest-mile wind speed during Frederic, reduced to started height and exposure, was 106 mph. the mobile homes suffered severe damage, but the conventionally built clubhouse was virtually undamaged. Wall Failures The specification of the wind loads on the walls has generally been quite adequate, except perhaps when a high internal pressure develops. Andrew quickly traveled due west across the peninsula and diminished to a category 3 hurricane. Figure 11.21 shows the 500-mb chart over four of the five days that Elena threatened the Gulf Coast. The results of these tests formed the basis of revisions to the Standard Building Code. Although of an unusual shape and in a very exposed location, these relatively heavy concrete-shell roofs had apparently been properly designed to resist the expected wind loads. Figure 4-39 Well-constructed modem building, near Fort Gaines, Dauphin Island. Figure 4-2 Roof membrane damage to a shopping mall, Gautier. This chapter concentrates on areas that sustained major wind damage. For example, a roof deck may resist wind forces applied directly to it, may act as a diaphragm to distribute wind forces applied to the walls, and may supply lateral support to those walls. Aftermath of Hurricane Elena in Appalachicola in 1985. Most were fairly well sheltered; nevertheless, many mobile homes turned over because their anchors pulled out of the ground (Figure 4-18). Figure 4-44 Loss of roof, Isle Dauphin Country Club, Dauphin Island. One exception was that a significant number sustained damage to their roof coverings, resulting in extreme water damage to their contents. Good inspection is required for the actual structure to, TABLE 4-5 Maximum Pressures of Underwriters Laboratory 580 Specification (lb/ft 2). The simpler Standard Building Code could have been justified had it led to conservative design pressures, but it is shown below that in many cases it seriously underestimated them. Roof spans are usually longer and walls higher. The earliest building codes simply specified a pressure to be used at a particular location and height, which then had to be multiplied by a shape factor, essentially a pressure coefficient. Hurricane Elena displaced at least 1.7 million people and left more than $1 billion in damages and lost holiday business in four Gulf Coast states over the … Building sustained no wind damage. The roofing membrane had been removed from most of the buildings. Hurricane Elena near its peak as seen from the Space Shuttle Discovery (NASA) Midday on September 2, 1985, Hurricane Elena came ashore near Biloxi, MS. Failure of built-up roof coverings caused water damage in several several buildings. Figure 4-6 Buckling of bar joists due to roof uplift, Jackson Square Shopping Center, Gautier. It should be pointed out, however, that this eventuality is rarely considered in the design of such buildings. Loss of watertightness also proved to be a problem for many other buildings, including the new Vocational High School in Pascagoula and several buildings located at the Jackson County campus of the Mississippi Gulf Coast Junior College (Figure 4-28). © 2020 National Academy of Sciences. Had they been designed in accordance with SBC2, houses with steeper-pitched roofs would have stood little chance of survival. For a detailed discussion of damage to metal buildings, see Appendix C. Employing the scheme advanced by Minor and Mehta (1979), buildings that receive specific, individualized design attention from professional architects and engineers for all aspects of the building from cladding to the foundation are classified as fully engineered. About 1.5-million people - including 300,000 in the Tampa Bay area - were evacuated, some of them twice in four days. Ready to take your reading offline? It therefore appears strange that such extensive damage took place during Elena when the wind speed, reduced to the same averaging time, height, and exposure at Fort Gaines within a few miles of the bridge, was only 96 mph. But the procedure is also applied to conditions when the critical loading is a combination of only dead and wind load, as in the case of roofs subjected to uplift. You're looking at OpenBook, NAP.edu's online reading room since 1999. Following Hurricane Camille, the county took steps to improve the wind resistance of nonengineered structures. Some damage did take place where buildings were exposed. Meteorological history SBC3 also gives the designer the option of considering the building to be partially enclosed. However, two, major failures took place when walls were blown inward where, internal pressure was not a factor. Figure 4-49 Undamaged modern metal building, Dauphin Island. Fortunately, most coastal jurisdictions have recognized the inadequacy of the toenail connection and require the use of proper anchors, at least for residential construction. Exact date shot unknown. A review of damage sustained during the two prior events (Marshall et al., 1971; Mehta et al., 1983) compared with that observed by the investigation team for Elena indicates, for the most part, a significant improvement in performance of preengineered metal buildings. Several tornadoes occurred in central Florida when Elena was stalled off the west coast of Florida. The motel shown in Figure 4-26, a typical of other motels in this area, suffered damage only to the exterior logo and was returned to service immediately after restoration of electrical power. It can be seen that fastener loads were increased by factors as high as 2.8 for buildings that are expected to experience only normal internal pressure fluctuations (enclosed buildings) and 3.1 if it is assumed that the building envelope may be breached (partially enclosed buildings). Unfortunately, the test procedure falls short of predicting purlin or girt performance, and consequently it is difficult to relate the capacities of Class 60. This building is a good example of one in which the components probably met the code requirements (with the possible exception of the unreinforced masonry walls), but the structural system proved inadequate because of poor connections. At most, they would have been designed for uplifts of abut 30 lb/ft2. Newer buildings constructed by the University of Alabama in the style of elevated beach houses suffered only minor vent damage (Figure 4-39). Figure 4-40 Undamaged older beach house with steep-pitched roof and protected windows, Dauphin Island. Find high-quality Hurricane Elena stock photos and editorial news pictures from Getty Images. Thus, the averaging time depends on the wind speed. Due to its powerful winds, Elena caused $2.7 billion in damage (2005 USD), primarily in property damage. Damage from the storms consisted of people having damaged or lost roofs, and wall damage. The codes in use had been steadily tightened in the light of hurricane experience and by 1969, Gulfport, Biloxi, and Pascagoula had adopted the Standard Building Code. Photo is dated 09--1985. Note the removal of the roofing membrane in the areas of high suction. At the front of the store the bar joist bearing plates had been set in mortar, which apparently had not adhered well to the block or bars (Figure 4-9). Elena's unusual path through the Gulf of Mexico, which included a loop, caused many people to evacuate from the coastline. Failure of Roof-Supporting System This failure generally resulted from the pulling out of the joist anchor from a masonry wall, often following the failure of a nearby window. where F = force in lb, p = pressure in lb/ft2, Cp = pressure coefficient, q = velocity pressure = 0.00256 V2(lb/ft2), A = tributary area in ft2, and V = local wind speed in mph. Not surprisingly, many buildings that performed satisfactorily in other respects suffered severe damage to the waterproof membrane. Figure 4-32 Base-to-column connection of shelter of Figure 4-31. Several injuries resulted, but there were no reported fatalities. As land values have risen, beach houses have become larger, and prefabricated trusses spaced at 2 ft on center have become more common. Please look at the images below carefully to determine the condition of this vintage photograph, as it may not be in perfect condition. Click here to buy this book in print or download it as a free PDF, if available. Presumably, the logic behind this is that it is unlikely that the design wind load, live load, and dead load will occur at the same time and/or that the peak wind load will be of short duration. Storm-related damage to The Bahamas was estimated at $250 million, whereas damage to property in the United States was roughly $26.5 billion. The three alternative quarter-roof conditions, suitable for the design of a roof framing system, included appropriate internal pressure coefficients. Considering the damage sustained by many schools on the mainland, it is interesting to note that the small wooden school on Dauphin Island survived with very little damage, as it had in Hurricanes Frederic and Camille (Figure 4-50). The area is under the jurisdiction of Mobile County, which has adopted the Standard Building Code. Figure 4-22 shows a typical contrast between the performance of buildings in which local effects were, or were not, considered in the initial design. These buildings usually had steep-pitched roofs, and many had hipped roofs, including some that probably predated any building control. Compared with the losses sustained, the initial cost would have been negligible. Note that these are considerably larger than those recommended by any of the earlier editions of the Standard Building Code or the SFBC. Hurricane Elena, following an erratic and difficult-to-forecast course along an unusually large section of the Gulf Coast, posed special problems from New Orleans, Louisiana, to Sarasota, Florida, well before it came ashore on September 2, 1985. ated in that corner. Thus, the buildings were, in essence, being designed not for fastest-mile wind speeds of 110 mph, but for gust wind speeds of 110 mph. The bar joists. Hurricane Elena was a category 2 hurricane from Aug. 30-Sept. 1; category 3 from Sept. 1-landfall in Mississippi . ings, the Dolphin Surf Beach Club and the Sand Castle Condominiums (Figure 4-46). Hurricane Elena was responsible for no direct deaths, though four people were indirectly killed due to the storm. In cases where the anchors held, damage to the superstructure was extensive (Figure 4-19). The high internal pressure probably resulted not from glass breakage but from failure of the wall-to-window-frame connection (Figure 4-5). Regrettably, economic conditions and the competitive nature of low-rise construction may have encouraged some members of the industry to continue to use the older provisions even though the improved alternative procedures had been adopted by the Standard Building Code in 1982. Hurricane Elena was a category 3 major hurricane that caused heavy damage along the Gulf Coast of the United States in August and September of the 1985 Atlantic hurricane season.. Elena's unusual path through the Gulf of Mexico, which included a loop, caused many people to evacuate from the coastline. Figure 4-18 Anchor failure in mobile home, Gautier. Nearly all had protected windows, and those that had large porch overhangs had them securely bolted to columns (Figures 4-40 and 4-41). To search the entire text of this book, type in your search term here and press Enter. Considerable wind damage occurred in this area to structures that were ostensibly designed to resist such extreme wind conditions. In others, usually where the glazing system had failed, the decking was also removed. Clearly, buildings of this type were being designed not for events with a 100-year recurrence interval, as the code implied, but for events with a much higher frequency of occurrence. Figure 4-7 Collapse of Payless Shoe Store, Pascagoula. Figure 4-25 First Baptist Church of Lyman. Damage ranged from roof leakage due to the sucking off of the waterproof membrane to serious roof damage and the collapse of walls. (Note damage to sign in foreground.). A detailed survey of mobile homes was not conducted, but a few mobile home sites were visited. The post-and-lintel framing provided little moment resistance either to the bases of the columns (Figure 4-32) or at the roof-to-column connections (Figure 4-33), and all units collapsed in the storm. protection of windows, or size of roof overhang and wind exposure (Hessig, 1986; Sparks et al., 1988). The satisfactory performance of schools in a hurricane is important, since they are often used as evacuation shelters. However, a major tightening of regulations came after Hurricane Camille, at which time the South Florida Building Code (SFBC). Paneling was sometimes sucked from the corners of buildings. The second factor that probably led to improved performance is the almost uniform acceptance of the UL 580 specification as a marketing strategy by the metal building industry. The total damage from the storm is estimated at $1.25 Billion. {{filterDisplayName(filter)}} Duration. Traditionally, damage surveys have classified buildings into fully engineered, marginally engineered, nonengineered, and preengineered structures. Table 4-1 shows the design pressures prescribed under normal conditions by the three versions of the Standard Building Code and the South Florida Building Code for a building located on the Mississippi coast. On the negative side, a number of metal building systems performed in a less than satisfactory manner and sustained damage ranging from minor cladding failures to loss of an entire end bay of the building. Tampa Bay residents became glued to their TVs, watching as it drifted lazily around the gulf as wind and rain pounded the area. The experimental values given at the bottom of Table 4-7 represent the expected upper bound of the forces. Figure 4-43 Repeated damage patterns in similarly constructed buildings, Dauphin Island. For buildings approaching 30 ft, the velocity pressures would be underestimated by approximately 25 percent. Figure 4-8 Bar-joist-to-wall connection, Payless Shoe Store. Based on the requirement for resistance to high local suctions specified by the Standard Building Code for the top surface of the roof, the most stringent classification, 90, would be required for flat roofs in this area. 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