Pre-engineered Buildings Research Articles

Full scale test and alnalytical evaluation on flexural behavior of tapered H-section beams with slender web

In December 2005, one(A) of the two pre-engineered warehouse buildings in the port of K City of Korea was completely destroyed and the other(B) was seriously damaged to be demolished. Over-loaded snow and unexpected blast of wind were the causes of the accident and destructive behavior was brittle fracture caused by web local buckling and lateral torsional buckling at the flange below rafter. However, the architectural design technology of today based on material non-linear method does not consider the tolerances to solve the problem of such brittle fracture. So, geometric non-linear evaluation which includes initial deformation, width-thickness ratio, web stiffener and unbraced length is required. This study evaluates the structural safety of 4 models in terms of width-thickness ratio and unbraced length using ANSYS 9.0 with parameters such as width-thickness ratio of web, existence/non-existence of stiffener and unbraced length. The purpose of this study is to analyze destructive mechanism of the above-mentioned two warehouse buildings and to provide ways to promote the safety of pre-engineered buildings.

Applying Neural Networks in Case-Based Reasoning Adaptation for Cost Assessment of Steel Buildings

Case-based reasoning (CBR) refers to both a cognitive and a computational model of reasoning by analogy from past cases. It is often more efficient to solve a problem by starting with the solution(s) to a previous similar problem than it is to generate the entire solution again from first principles. In fact, experts have been observed to reason by analogy to prior cases. Case adaptation, a central component of case-based reasoning, is often considered the most difficult part of a case-based reasoning system. The difficulties arise from the fact that adaptation does not often converge, especially if it is not done in a systematic way. This problem, sometimes termed the assimilation problem, is especially pronounced in the case-based design problem-solving domain where a large set of constraints and features are processed. Furthermore, in the steel building design domain, multiple cases must be considered in conjunction in order to solve the new problem, resulting in the difficulty of how to efficiently combine the multiple cases into one solution for the new problem. This article investigates a new technique in complex adaptation. It presents the closest retrieved cases to a neural network, thus learning about the domain of the problem being solved. The new problem is then fed to the trained neural network and the output becomes the solution to that problem. The methodology is applied to a problem in steel construction, and the sought output is the cost estimation of pre-engineered steel buildings. Several experiments are conducted to prove that these steps are successful. System verification is done and shows that both the system and the methodology are successful in developing a complete adaptation mechanism in CBR.

Impact of Changes to Building Airtightness on HVAC Costs

Air leakage is generally the most significant factor in small-building energy consumption. This study determined if reducing air leakage in preengineered metal buildings would be cost-effective. The effects of air-retarder treatments on owning and operating costs were examined for two different sizes of buildings that were thermally modeled using a building energy analysis computer program, BLAST. The annual energy consumption and peak loads were then produced by BLAST to find the fuel consumption for each building and the system sizes needed for adequate climate control. A detailed cost estimate was done on the mechanical system based on the required equipment size for each air-retarder treatment used. Life-cycle costs were determined for two types of air retarder and one case without an air retarder at four locations in cold and hot climates, and for five air exchange rates. A payback analysis illustrated the cost-effectiveness of the air-retarder treatments. Both air-retarder treatments proved cost-eff...

Performance of metal buildings in high winds

Hurricanes Camille (1969), Frederic (1979) and Elena (1985) subjected the Gulf coastal region to wind speed regimes at or near design level events. Additionally, during this time interval, the wind load provisions of ANSI A58.1 and the industrial standard for Metal Building Systems (MBMA) had undergone extensive revisions. Tens of thousands of steel-framed, pre-engineered buildings were affected by these three hurricanes providing valuabel field evidence to assess structural performance. The object of this communication is to review the damage patterns inflicted by these major storms and suggest mitigation strategies for reducing the damage to metal building systems.

Performance of metal buildings in high winds

Hurricanes Camille (1969), Frederic (1979) and Elena (1985) subjected the Gulf coastal region to wind speed regimes at or near design level events. Additionally, during this time interval, the wind load provisions of ANSI A58.1 and the industrial standard for Metal Building Systems (MBMA) had undergone extensive revisions. Tens of thousands of steel-framed, pre-engineered buildings were affected by these three hurricanes providing valuabel field evidence to assess structural performance. The object of this communication is to review the damage patterns inflicted by these major storms and suggest mitigation strategies for reducing the damage to metal building systems.

Failures of Structures Due to Extreme Winds

Urban sprawl has increased the frequency with which windstorms interact with structures. The Lubbock Storm (May 11, 1970) and Hurricane Celia (August 3, 1970) provide the most recent examples of storm incidence on populated areas. The responses of engineered structures to extreme winds are characterized by window glass breakage and failures of nonstructural components, each of which can lead to progressive failures of the structure. Pre-engineered buildings experience wind induced progressive failures because of overhead doors which are not designed as integral parts of the structure. Failures in pre-engineered buildings include buckling of purlins and girts throughout the structure due to wind induced outward pressures, and buckling of purlins spanning between end frames and first interior frames due to wind induced axial load. Marginally engineered structures (including residences and some light commercial buildings) experience wind induced failures which are the result of inadequate connections between roofs and walls, and between walls and foundations, i.e., the result of the buildings not being designed as integral structures.

Buckling of Light-Gage Corrugated Metal Shear Diaphragms

Formulas for the elastic buckling loads of shear diaphragms are derived. They are obtained from an analysis of light-gage, corrugated-metal diaphragms of the type that occur in pre-engineered metal buildings. The formulas are applicable to any rectangular, orthotropic plate loaded in pure shear, and they are derived using orthotropic plate theory and the Ritz energy method. Small deflection theory is used first to establish critical loads and buckling modes. Then, large deflection theory is used to predict post-buckling load versus lateral deflection relationships. The results of experiments that were designed to verify the accuracy of the formulas are presented in the form of load versus lateral deflection curves covering the pre and post-buckling ranges. Several light-gage, corrugated-metal diaphragms of different size and corrugation shape were tested to determine their buckling behavior. The results of the experiments compare favorably with the formulas derived.