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Description: This UFC presents methods of design for “ voivestawimon.ml”: This file will allow you to view the complete UFC as. UFC Structures to Resist the Effects of Accidental Explosions - Ebook download as PDF File .pdf), Text File .txt) or read book online. Blast resistant. masonry components in UFC , “Structures to Resist the Effects of PEC and the UFC Technical Working Group (TWG) are.
Google Scholar Belytschko, T. Google Scholar Chopra, A.
Google Scholar Cormie, D. Blast effects on buildings, 2nd Ed. London: Thomas Telford.
Washington, DC. Google Scholar DoD Departments of Defense, Washington, DC. Google Scholar Dusenberry, D.
Handbook for blast-resistant design of buildings, Wiley, Hoboken, NJ. Google Scholar Norris, C.
However, it is very difficult to capture the overall system response if a building is broken into discrete components with simplified boundary conditions using the SDOF approach, with the result that the SDOF method may be overly conservative.
Nonlinear finite element analysis methods may be used to evaluate the dynamic response of a single building module or a multi-module assembly to blast loads.
This global approach can remove some of the conservatism associated with breaking the building up into its many components when using the SDOF approach. Geometric and material non-linearity effects are normally utilized in such analyses.
These analyses are typically carried out using a finite element program capable of modeling nonlinear material and geometric behavior in the time domain. The following shows a finite element model for a six-module complex: SDOF Analysis: All structures consist of more than one degree of freedom. The basic analytical model used in most blast design application is the single degree of freedom SDOF system.
In many cases, structural components subject to blast load can be modeled as an equivalent SDOF mass-spring system with a nonlinear spring. This is illustrated below: The accuracy obtainable from a SDOF approximation depends on how well the deformed shape of the structure and its resistance can be represented with respect to time. The properties of the equivalent SDOF system are also based on load and mass transformation factors, which are calculated to cause conservation of energy between the equivalent SDOF system and the component assuming a deformed component shape and that the deflection of the equivalent SDOF system equals the maximum deflection of the component at each time.
The mass and dynamic loads of the equivalent system are based on the component mass and blast load, respectively, and the spring stiffness and yield load are based on the component flexural stiffness and lateral load capacity.
Blast loadings, F t , act on a structure for relatively short durations of time and are therefore considered as transient dynamic loads.
The equivalent SDOF system is an elastic-plastic spring-mass system with properties M, K, Ru equal to the corresponding properties of the component modified by transformation factors. The deflection of the spring-mass system will be equal to the deflection of a characteristic point on the actual system, i.
To perform equivalent SDOF, the assumption of a deformed shape for the actual system is required. The majority of dynamic analyses performed in blast resistant design of petrochemical facilities are made using SDOF approximation.
The following figure from UFC shows the maximum deflection of elasto-plastic, one-degree of freedom system for triangular load and this figure is typical graphical solution of SDOF.