Browsing by Subject "Wind-pressure"
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Item A failure prediction model for window glass(Texas Tech University, 1980-05) Beason, William L.There is a need within engineering practice for an analytical method to predict the probability of failure of window glass plates subjected to lateral loads. The failure prediction technique should include provision for all significant factors which influence glass strength and all significant factors which influence plate behavior The ultimate use of the glass plate failure prediction model will be to provide a realistic assessment of glass plate strength to be used in the design of window glass.Item A model for time varying wind loads on a low-rise structure(Texas Tech University, 2001-05) Fagan, Rebecca BimmermanOverall loads acting on a full scale building in the natural vdnd environment are characterized in this work. The first objective of this research is to directly measure the overall wind loads on the test building at the Wind Engineering Research Field Laboratory (WERFL) in the natural wind environment. The measurements are accomplished using four load cells, with one load cell placed at each comer of the building. These four load cells support the entire weight of the building, and each cell measures two shear forces and one vertical force acting at its comer of the building. These twelve forces were combined to measure total uplift, total horizontal shear, along, and across wind response. Mean drag coefficients are calculated from these measurements in the natural wind environment and are compared to wind tunnel. Uncertainty in the measurements was expected, as several aspects of full-scale testing are difficult to control. Thermal reactions of the WERFL undercarriage were time varying and the variable weight distribution occurred upon lowering the undercarriage onto four point supports. The second objective of this research is to develop a mathematical model using system identification to relate the three orthogonal fluctuating components of wind induced forces to the along, cross and vertical components of wind speed. An ARX (5,5) was found to be appropriate to capture the relationship between the free-stream wind turbulence and the turbulent wake characteristics. This model may then be used to generate modeled data or describe spectral relationships. Investigation in the frequency domain indicates that the building acts as a low-pass filter with the half-power frequency of 0.08 Hz.Item A parametric study of dynamic response of rectangular window glass plates(Texas Tech University, 1989-05) Kamineni, SridharNot availableItem A stochastic model for purlin response(Texas Tech University, 2000-12) Zhou, NanTime series models can provide an economical computational technique for an engineer for modeling wind speed, wind-induced pressures, and the response of a structure (or one of its components) to wind loads. Time series models are compact; yet contain almost all of the information that is in the original data. When combined with functional relationships that link the model parameters to physical parameters, a general description of the process is provided. Autoregressive (AR) models are used in this thesis to characterize wind speed, wind-induced pressure, and associated wind-induced purlin displacement response data. The data used for the characterization was collected at the Texas Tech University's Wind Engineering Research Field Laboratory (WERFL). Autoregressive models of order 3 characterize the wind speed, wind-induced pressure, and purlin response adequately. The AR model parameters exhibit linear correlation of varying degree depending on the data type (e.g. wind speed, wind-induced pressure, or purlin response). This implies that by establishing a single model parameter, the complete model is specified. The relationships of the model parameters to physical parameters are explored. This investigation shows that the AR (3) model parameters for wind speed are closely related to the variance of the wind speed. Although not fully developed in this work, there appears to be a functional relationship between the models for wind speed, windinduced pressure, and the associated structural response of a member. Preliminary investigation indicates that this relationship is likely to be independent of the angle of attack. Further, the residuals of autoregressive models on both wind speed and purlin response can be reasonably characterized using the log-logistic distribution.Item A uniform approach to design of windloads on structures(Texas Tech University, 1987-12) Chen, Yuan-Bin"Uniform" is defined as having the same manner, and "approach" is defined as a path road or other means of reaching a certain thing. Therefore, combining these two words, "uniform approach," means having the same manner of reaching a certain thing in general. A uniform approach to design for wind ioads implies using the same methodology when treating straight winds, hurricane winds and tornado winds.Item Analysis of Data for the Response of Full-Scale Transmission Tower Systems to Real Winds(Texas Tech University, 1983-05) Jan, Con-linNot Available.Item Analysis of field data for wind profile(Texas Tech University, 1985-05) Khayrattee, Jaynool AbedeenOne of the principal loads acting on above-ground structures is that due to wind. In tall structures, say above 100 feet high, often the wind forces become the controlling factor in structural design. In such tall structures economy in design is achieved by a correct assessment of the wind profile (wind speed variation with height)- The wind forces acting on a structure are a function of the square of the wind speed. Therefore, a good knowledge of the wind profile which defines the variation of wind speed is essential for appropriate assessment of the wind forces. Among the variables for wind profile are the height above ground, the roughness of terrain, the intensity of wind speed and the averaging time of the mean wind speed.Item Analysis of reference pressure systems used in field measurements of wind loads(Texas Tech University, 1993-05) Levitan, Marc LloydThe main problem then left to be solved for making accurate measurements of wind-induced pressures on full-scale structures lies in reaching a greater understanding of the effects of reference pressure systems on these measurements. At present, it is difficult to even quantify the measurement error associated with the reference pressure system, and little information is available to help improve reference pressure system design.Item Analysis of wind characteristics from field wind data(Texas Tech University, 1987-05) Kancharla, Vidyasagar ReddyNot availableItem Application of the boundary element method for tornado forces on buildings(Texas Tech University, 1985-08) Selvam, Rathinam PanneerNot availableItem Comparison of wind load standards(Texas Tech University, 1995-12) Kola, ShrinivasThe objective of this thesis is to compare major recognized national standards of wind loads and to determine the correlation among them. The four national standards compared are American Society of Civil Engineering Standard, ASCE 7-95 (ASCE 7-95), Australian standard, SAA Loading Code, Part 2: Wind Loads, AS 1170.2-1989 (SAA, 1989), British standard, Part 2, Code of Practice for Wind Loads, BS 6399, 1994 (BS 1994), and National Building Code of Canada, 1990 (NRCC 1990). The objective was accomplished by calculating wind loads on two buildings: a low building with dimensions of 100 ft x 60 ft x 15 ft and a 160 ft high building with a plan dimensions of 200 ft x 100 ft. Limit state base shear and overturning moments for the two buildings were calculated and then compared. The study shows that the four national standards give similar limit state base shear for the two specific buildings selected for the study. It is also seen that the overturning moment depends largely on the roof uplift. The roof uplift force obtained from using the four national standards vary significantly which indicates that a thorough parametric study on roof uplift loads should be conducted to assess the real loads. The design pressures on components and claddings differ between the standards by as much as 200 percent. While accomplishing the objective it was observed that the comfurtability in using any standard depicts the format of the standard in some manner. The study shows that for that the format of the American and the Canadian standards are easy to follow, while the Australian and the British standard are more difficult to use to when determining the wind loads.Item Critical evaluation of metal building systems subjected to extreme wind loads(Texas Tech University, 1990-12) Shanker, AjayNot availableItem Direct measurement of wind loads on a low-rise test building(Texas Tech University, 1998-05) Bird, Mark WesleyWind loads on low-rise structures are studied in the field primarily so that the results obtained can be used to provide a base-line data set and to assist in wind tunnel studies. The objective of this work is to develop a means of directly measuring total wind loads in the field on a low-rise test building. This project is part of the Texas Tech University / Colorado State University Cooperative Program In Wind Engineering to study wind effects on low-rise buildings. The experimental facility utilized is the Wind Engineering Research Field Laboratory (WERFL) on the campus of Texas Tech University. This thesis contains development of an experimental procedure for directly measuring total wind-induced loads (total horizontal shear and uplift) on the 30 ft x 45 ft x 13 ft test building along with some preliminary results. These loads are measured by supporting the entire building on four load cells(one at each corner). The load cells were constructed in the laboratory to register force in the three orthogonal directions. Forces recorded by the load cells and pressures recorded at the 12 pressure taps (windward wall, roof and leeward wall) are used to measure wind-induced loads. Data utilized In this project is limited to records with winds normal to long axis of the building collected in February and March of 1995. A total of twelve 15-minute records are used in the analysis. Analysis of data indicates difficulty in obtaining a reference load (when wind Is zero). A procedure to overcome this difficulty is suggested. Preliminary results show that overall loads measured using the load cells are smaller than the ones obtained from the integration of pressure tap values. However, there is significant uncertainty and scatter in the results obtained from the load cells.Item Environmental design directed at decreasing the wind damage experienced from hurricanes in single-family residential communities(Texas Tech University, 1997-12) Gardner, Anna G.In 1992 hurricane Andrew inflicted approximately $25 billion in damage in Dade county, FL, resulting in the costliest hurricane in U.S. history (Landsea 1997 Internet). Documentation and analysis of hurricane Andrew's wind damage substantiates Minor and Mehta's (1979) identification of initiation points of failure in low-rise structures experienced during tomadic winds. These initiation points of failure occur at points experiencing high wind pressures which a direct resuh of poor aerodynamic configurations found in most conventional buildings (Minor and Mehta 1979 pg. 2285). If the aerodynamics of a structure influence which components of a building frequently fail, then one could reason that the aerodynamics of a community would influence which structures will frequently fail. This study identifies five street/road patterns or typologies commonly found within a residential community. The aerodjmamic qualities of each typology are predicted and each structure in the pattern is rated according to the expectation of damage relative to the structure's location. Once these damage herarchy predictions are made a case study community is coded according to the degree of roof damage each structure experiences in order to prove or disprove the initial hypothesis. The case study is a community damaged by hurricane Andrew on 24 August 1992, located in east Culter Ridge, Florida and has an approximate area of 2.15 km^ (0.83 mi^). Windbreak placements are suggested for improving the aerodynamics for each intersection typology along with suggestions for improving the wind flow around individual structures and their use in combating windbome debris. The objective of this thesis is to create design recommendations to aid community designers, developers, architects, and engineers in analyzing and improving new and existing communities for extreme winds.Item Evaluation of a building with respect to wind in an integrated windows environment(Texas Tech University, 1995-12) Teal, Mark H.Evaluating a building's performance in a windstorm has previously been a long, coitputationally intensive, manual process. It has also required the time of an expert to perform all of the calculations to insure the latest knowledge of wind/building interaction is properly used to guide the process and interpret the results. This paper presents the integration of a knowledge based expert system with more traditional algorithmic programs in an effort to automate the evaluation. The expert system uses knowledge gleaned from actual experts in wind engineering to guide the repetitive calculations and comparisons, which the algorithmic programs can accorrplish many times faster than a human. The Microsoft Windows operating system offers a number of different methods of intertask communication, user interaction, and data management. Ultimately, the user must have convenient access to the database auid knowledge base, as well as an accurate analysis of the building. Different combinations of intertask communication have been explored, noting their appropriateness in terms of memory limitations and time consumption.Item Evaluation of the Potential Performance of Hospital Buildings in Windstorms(Texas Tech University, 1978-08) Lea, Patrick AlanNot Available.Item Experimental study of edge displacements of laterally loaded window glass plates(Texas Tech University, 1979-05) Anians, Duncan CliveNot availableItem Experimental study of glass plate strength at rapid loading rates(Texas Tech University, 1986-12) Pal, Himansu SekharThe time dependent nature of the strength of glass plates, commonly referred to as "static fatigue," is modeled by an equation involving an exponent "n" which is a material property relating to the rate of loading. Except for field explosion and shock tube tests, which were not instrumented for detailed response, glass plate tests to date have been essentially static. The highest loading rate achieved so far in a laboratory has been 3.6 psi/sec. The main objective of this study is to investigate the value of "n" at rapid loading rates. Secondary objectives are experimental verification of a nonlinear analytical model for dynamic plate response and of a dynamic failure prediction model for window glass. This dissertation presents and evaluates results of six series of tests to failure on 27" x 32" x 0.088" glass plates for loading rates ranging between 0.01 and 240 psi/sec. Each test series consisted of at least twenty specimens. The series with the slowest loading rate was tested in a conventional static test set-up. For the other five series, each plate was loaded in uniform air suction by rapidly pulling a plunger away from the plate which was mounted on a chamber. In the two series with slower loading rates, the plunger movement was controlled by a universal testing machine. For the three series with faster loading rates, the plunger was activated by a dropping weight. For the oscillating stress-time histories found at the most rapid loading rates, direct determination of "n" is not judged to be appropriate, and an indirect method is employed. The value of "n" is found to increase as the loading rate increases. The nonlinear dynamic finite difference model is shown to agree well with the experimental plate response, and the dynamic failure prediction model for glass plates is validated by the breakage results. The results of these experiments should aid in the prediction of the strength of window glass plates under rapid loading.Item Factors affecting tornado hazard probability(Texas Tech University, 1980-08) LaGreca, Kenneth WilliamNot availableItem Failure strengths of laminated glass units(Texas Tech University, 1986-08) Reznik, Patrick LawrenceNot available
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