Hurricane Wind Loads Research Articles

Personalized Vulnerability Assessment of Customized Low-Rise Wood-Frame Residential Structures under Hurricane Wind Loads: A Flexible Scenario-Based Simulation Approach

Hurricanes are one of the costliest and deadliest weather and climate disasters that impact the United States, largely affecting the residential sector. Residential structures are essential for the health and safety of the community during a hurricane event. However, homeowners typically have to rely on general information and instructions to understand their level of risks. The knowledge of structural vulnerability to hurricanes at the individual residential building level is often limited, which hinders personalized disaster preparation and mitigation decision-making. To this end, a vulnerability assessment method is proposed for individual homeowners to create customized finite-element models that quantify wind damage of low-rise wood-frame residential structures under various scenarios using ANSYS 2020 R1 parametric design language. A case study was conducted to test the proposed methodology and investigate prevailing failure modes under different structural characteristics and wind scenarios. Specifically, the impacts of roof framing features and previous exposure to environmental conditions on the potential damage of residential buildings under hurricane wind loads were studied. Analysis results, including the percentage of failed sheathing, nailed connections and framing members, are used to inform personalized mitigation recommendations. The proposed customized vulnerability assessment may increase homeowners’ situational awareness of disasters and promote rational retrofitting decisions.

Integrated analysis of LNG tank superstructure and foundation under lateral loading

Liquefied natural gas (LNG) storage tanks are often supported by very large pile groups (≥100 piles), which can experience substantial lateral loads such as hurricanes, earthquakes, and floods. However, the existing design standards are premised on the experimental results of the small pile groups (<25 piles). Furthermore, the current design practice considers the superstructure and foundation independently, which apparently do not reflect the soil-pile-superstructure interaction. This study aims to observe how the presence of the LNG tank superstructure influences the foundational response of a 1600-pile group and assess whether the current design approach used in practice is suitable. Three-dimensional finite element models were employed to compare traditional, de-coupled foundation models to the integrated tank-foundation models under Category 3 hurricane wind loads. Effects of LNG weight and foundation stiffness were investigated for the comparison. The results found that large pile groups had greater influence depths of lateral responses than small pile groups. The foundation response in the integrated model varied significantly from the foundation-only models. The amount of LNG in the tank, soil condition, and pile spacing also affected the lateral pile responses, particularly the leading and trailing piles.

Fiber Reinforced Polymer as Wood Roof-to-Wall Connections to Withstand Hurricane Wind Loads

Light wood roof-to-wall connections are vulnerable when subjected to high-speed winds. In lieu of traditional metal connections, the present finite element analysis (FEA) study focuses on the use of epoxy and easy-to-apply, noncorrosive FRP ties to connect the roof and the walls in wood frames. The FEA models of the wood roof-to-wall GFRP connection were validated with an experimental study in the literature. Subsequently parametric study was performed on the validated FEA models. Parameters considered were the addition of anchorages to secure the GFRP ties for FEA models of shear and uplift tests, and various FRP types. Wood roof-to-wall connection uplift model was subjected to monotonic cyclic loading to simulate the effect of wind load. In addition, carbon and basalt FRP ties were also examined under monotonic cyclic loading. To evaluate the efficiency of GFRP ties with and without anchorages, the shear and uplift design loads specified in ASCE 7-16 were calculated. Finally, a formula was proposed to approximate the shear strength of GFRP connection in comparison with double shear bolted metal plate connections. The FEA models and experimental results were in good agreement. The finite element results revealed that anchorage increased the uplift load capacity by 15% but the increase in shear capacity was insignificant. Comparing glass, carbon, and basalt FRP ties, BFRP was superior in deformation capacity and CFRP provided more stiffness on uplift test simulation. GFRP ties were found to be approximately nine times stronger in shear and two times stronger in uplift resistance than hurricane clips. Finally, the proposed formula could predict the shear strength of GFRP tie connection which in turns contributes to the design and future research.

CFD-Based Evaluation of Elevated Coastal Residential Buildings under Hurricane Wind Loads

Abstract Many elevated houses in coastal areas have suffered serious wind-induced damage during hurricanes; this indicates the need for better understanding of the performance of elevated homes sub...

Fatigue life estimation of existing bridges under vehicle and non-stationary hurricane wind

During hurricane events, additional damages to existing bridge details might be accumulated from the large stress cycles generated by the non-stationary wind and dynamic vehicle loads. The environmental corrosion could also reduce the structural fatigue strength. Based on the non-stationary wind field modeling techniques and the vehicle–bridge–wind dynamic analysis framework, this paper initiates a fatigue damage assessment of existing bridges with corrosion under vehicle and non-stationary extreme hurricane wind loads. The non-stationary hurricane wind is simulated as a summation of time-varying mean and fluctuating non-stationary components with a time-varying spectrum. Dynamic stress histories are obtained by solving the vehicle–bridge–wind dynamic system. The rain flow counting method is used to obtain the stress ranges and numbers of stress cycles. The corrosion induced fatigue strength degradation is included in the analysis. Numerical examples of an existing long span bridge under simulated non-stationary hurricane winds and vehicles are presented to demonstrate the effects of the dynamic loads and corrosions on the fatigue life estimation of existing bridges.

Analysis of hurricane wind loads on low-rise structures

Time series of pressure coefficients collected on the roof of a house by the Florida Coastal Monitoring Program during landfall of Hurricane Ivan on the Florida panhandle in 2004 are analyzed. Rather than using peak values, which could vary due to the stochastic nature of the data, a probabilistic analysis is performed to characterize extreme values of pressure coefficients and associated wind loads. It is shown that the pressure coefficient time series follows a three parameter Gamma distribution, while the peak pressure follows a two-parameter Gumbel distribution. The analysis yields a probability of non-exceedance of a given threshold of the pressure or load coefficients. For this specific house and specific storm, the 80 percentile load coefficient value of the probability of non-exceedance is −1.7. This is discussed in the context of ASCE 7 GCp values.

Wind Load Effects on Manufactured Home Foundations

Problem statement: Manufactured homes are susceptible to hurricane damage. Each year, significant losses, in terms of fatalities and property damage, are reported. There is always a prevalent concern about lateral load resistance capacity of tie-down system of manufactured homes when subjected to windstorms. This study is performed to determine the effects of hurricane wind on manufactured homes’ foundations. Approach: A 1:120th scale model of single wide manufactured home of size 14 ft by 80 ft was designed for the wind tunnel test. Proper instrumentations and simulations were considered to measure wind forces applied on the model. Sting balance and Pitot static tube were used to measure forces and air velocity during the wind tunnel test. Displacements of anchors were observed during the test. Results: The ultimate forces as well as the displacements of the anchors were determined at different angles of wind direction ranging from 30-180°. Wind speed inside the tunnel was increased at the rate of 5 miles h-1. Conclusion/Recommendations: Test result showed that auger anchors used to support lateral load are incapable to resist hurricane wind loads. It was found that anchors displaced 2 in. vertically and 4 in. horizontally at loads less than 4725lb. Tested manufactured homes anchors experienced maximum force of 4087 lb when 45 miles h-1 wind acted in transverse direction to the wall. The manufactured home anchors displaced more than 2 inches in vertical direction and 4 inches in horizontal direction due to this wind load. This research indicated that manufactured homes ground anchors can sustain wind velocity of 95 miles h-1 when the wind is acting at longitudinal direction.

Field measurement and wind tunnel simulation of hurricane wind loads on a single family dwelling

During landfall of Hurricane Ivan on the Florida ’panhandle’ in 2004, pressure time-history data were recorded on multiple pressure sensors installed on the roofs of six single-family homes. An analysis approach was developed to determine the peak negative, mean, peak positive, and standard deviation of pressure coefficients for these datasets. This paper presents a comparison of the full scale pressure coefficients from one of these homes, which experienced sustained hurricane force winds, with the results of wind tunnel experiments on a 1:50 scale model of that home. It was determined that the wind tunnel and full-scale mean and rms pressure coefficients matched very closely at almost every monitored location on the roof, while the peak negative pressure coefficients in the wind tunnel study generally underestimated the full-scale values, consistent with observations from previous full-scale/wind tunnel comparative studies. Field-measured hurricane wind loads may prove useful for evaluating existing wind load provisions. However, recommendations in that regard are premature without the analyses of multiple homes in multiple storms, performed by more than one wind tunnel facility. Future work will focus on building such a joint study.

Floating Pumps Allow Easy Access to Remote, Problematic Reservoirs

This article describes how twin floating pump stations were developed for pumping water out of the In Town Lakes to be used for the emergency raw water needs of Chesapeake, Virginia. This was the first project of its kind on this scale east of the Mississippi River, as well as the first to involve the additional complications of wetlands, hurricane wind loads, intra‐lake recirculation, and muddy soils. The stations are 40 ft. by 40 ft. galvanized steel platforms, or barges, decked with lightweight concrete panels and placed on polyethylene encapsulated floats. Each station is equipped with two vertical turbine pumps with space for two additional pumps in the future. Operational procedures are discussed, along with construction advantages, water construction challenges, and hurricane preparedness.

House to Be Subjected to Hurricane Wind Loads in Structural Tests

House to Be Subjected to Hurricane Wind Loads in Structural Tests

Assessment of wind load factors for hurricane-prone regions

We study the issue of whether the wind load factors specified in the ASCE 7–95 Standard for hurricane- prone regions on the one hand and extratropical storm regions on the other are mutually consistent with respect to risk. We consider structures or elements whose design is governed by wind loads and for which wind directionality effects are not significant. We present estimates according to which ASCE 7–95 Standard provisions for wind loads inducing the design strength result in (1) safety levels that are considerably lower for hurricane-prone than for extratropical storm regions, and (2) estimates of mean recurrence intervals of hurricane wind loads inducing the design strength of about 500 y if epistemic uncertainties are neglected, and significantly lower than 500 years otherwise.

Low-rise building design for hurricane wind loads in South Florida

Over the past several years, the South Florida area has pioneered in developing practical and detailed standards for designing hurricane-resistant structures. No other areas of the U.S. have had to cope with the problems of construction to resist hurricanes as has South Florida. Standards were adopted to provide practical and economical means of coping with hurricanes and not only cover design methods and procedures but also provide practical means for code enforcement procedures. The standards are based on a 54 m/s (120 mph) design hurricane.

The Baton Rouge Hilton Tower An All-Precast Prestressed Systems Building

T he Hilton Tower, hailed as a 21story salute to Baton Rouge, Louisiana, was opened recently (see Fig. 1). The building is the tallest completely precast systems structure in the southern United States. In this structure the most advanced construction techniques are combined: Precast prestressed hollow-core slabs for floors and roof and large precast bearing and shear walls are connected and reinforced by high strength posttensioning bars. This interaction creates a stable structure able to resist normal service loads as well as hurricane wind loads. Corporate Square, Baton Rouge's prestigious new office park and business complex located at I-10 and College Drive, is the site of the $13 million (overall cost) 325-room hotel and convention center. The actual construction cost amounted to about $5.2 million. After a steel frame structure (priced and bid) proved to be well above the budget limit, a precast concrete system was proposed. The flexibility of the proposed system together with the ease in obtaining previous and well tested assembled detailing, erection, and cost data of the selected system allowed a rapid redesign of the structure. In 3

Computer Analysis of Offshore Drilling Platforms

Abstract This paper discusses some of themajor design problems related to anoffshore drilling structure and theseries of computer programsdeveloped by the Chevron Oil Co. to aidin the solution of these problems. Introduction The engineer concerned with thedesign of an offshore platform is facedwith two semi-conflicting goals:to design a safe platform to protect livesand the increasing investment requiredin these multi-million dollarplatforms, andto design a less costlystructure to keep unit productioncosts competitive. To most advantageously meet boththese goals the engineer must utilizethe best tools available. Adoption ofknown engineering science for use onthe digital computer is one of themajor tools that has been (and is stillbeing) developed in recent years. Ithas enabled the engineer to providemore rigorous solutions to many ofthe problems with which he is faced. The computer can play an importantrole as a tool to aid the engineer inthe design of an offshore platform. Structural Design Problems To more easily see how thecomputer can aid the engineer in thedesign of an offshore platform, it isnecessary to have some understandingof the structural problems involved. Some major problems encounteredare the high degree of indeterminacy, the variety of imposed live and deadloads, foundations and secondarystress effects. The degree of indeterminacy of aplatform is usually no greater thanthat found in the design of abuilding or bridge and is not, therefore, peculiar to the offshore oil industry;but the variety of loadings for theseplatforms is one of the most severeencountered in any structural design. LoadsLoads imposed upon a platformdiffer with the operating criteria of acompany and with the geography ofthe location. An example of theeffect of differing operating criteriawould be where, for the same location, one company would use aself-contained platform (all operations carriedon from the platform) and anotheruses a tender-operated platform (someoperations handled by a mooredvessel). An example of the geographiceffect would be the large ice loadsimposed upon a platform in CookInlet, Alaska. For the Gulf of Mexico, a varietyof loads must be considered in thedesign of a drilling platform:Static dead loads (weight of theplatform, production units, engines, mud tanks and pumps, etc.). Totalstatic dead load may range from 3,000tons for a small platform in 40 ft ofwater to 10,000 tons for a largeplatform in 200 ft of water.Installation loads, such as liftingor launching loads. Most operators inthe Gulf preassemble as much of theplatform in the fabrication yard aspossible, with the size of the platformsub-units usually governed by the liftand reach capability of the availableocean-going construction equipment. The addition recently of threerevolving 500-ton derrick and several largelaunch barges, in addition to the otherheavy construction equipment in theGulf, have enabled operators to installplatforms made up of much largerpieces. Now it is not unusual to have1,500- to 2.000-ton jackets (templates)launched on location with theremaining portions of the platform in350-to 400-ton sub-assemblies, lifted intoplace. Therefore, each unit must bedesigned not only as an integral part ofthe platform, but also as a unitcapable of being launched or lifted.Dead loads that move from onelocation to another, such as derrickand pipe rack loads. Pipe rack andderrick combined loads may rangefrom 300 to 1,500 tons. These loadsmove with the derrick as it shifts fromone well position on the platform toanother.Live loads, such as wind andwaves. This is where the design of anoffshore platform in the Gulf is mostsignificantly different from that ofmost any other structure. Hurricanewind loads may range from 60 to 70lb/sq ft of average surface area and, occurring simultaneously, hurricanewave loads may be 5 to 10 timesgreater than the most severe windloads. Both loads may occur, depending on the location, from anydirection. Of particular significance to thedesigner is that the centroid of thewave forces is proportionately higheron the platform with increasing waterdepth (Fig. 1).The varying combinations ofLoads 3 and 4. The drilling programof these platforms will normally rangethrough one or two hurricane seasons;therefore, the designer must concernhimself with many combinations ofwind-wave and moving dead loads, with each possibly determining thesize of members in a particularsection of the platform. JPT P. 1056ˆ