Download or read book Seismic Analysis of a United States Navy Structure Using Finite Element Modeling written by Jacob Nash and published by . This book was released on 2012 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this project was to investigate a United States Navy structure and evaluate the potential of the lifting rod, supporting a large mass at the top of the structure, to disengage from the structure due to seismic activity. A concern about the seismic loading of the structure was raised by an inspection team. The concern was that, in the event of an earthquake, the lifting rod would disengage from the structure due to vertical seismic actions. In order to accomplish the objective, seismic analyses of the structure were performed using finite element modeling. The geologic and tectonic settings of the site were investigated and the expected earthquake sources were determined. A probabilistic seismic hazard analysis was performed for the site, including a deaggregation of the earthquake sources affecting the site. The results of the probabilistic seismic hazard analysis were used to select three sets of bedrock acceleration time histories. Artificial acceleration time histories were generated based on the results of the probabilistic seismic hazard analysis and three of the time histories were selected. A finite element model of the structure was created using ABAQUS and seismic analyses were performed by applying the acceleration time histories. The results of the model were analyzed to determine whether or not the lifting rod disengaged from the structure. Plots of contact force vs. time indicated that there were a total of three increments of time where the lifting rod lost contact with the structure. Plots of relative vertical displacement vs. time indicated that there were no increments of time where the lifting rod was lifted up enough to detach. Plots of energy vs. time indicated that there were no increments of time where the kinetic energy of the mass was greater than the potential energy required for detachment. It was determined, based on the information at hand and within the hypotheses discussed in this document, that the lifting rod was not at risk of becoming detached.
Download or read book Do Seismic Analysis Using Finite Elements written by Phil Cooper and published by Lulu.com. This book was released on 2007 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book aims to provide practical guidance on the application of FEA to the seismic analysis of structures and equipment, and to inform the reader generally about seismic analysis. The intended audience is the practicing engineer (and to a lesser degree engineering managers). It is assumed that the reader has some understanding and experience of seismic engineering and FEA. Examples of actual applications of FEA to safety critical structures and plant are used to illustrate some of the techniques and guidelines given within this document. There is much literature on the subject of FEA, including other NAFEMS publications, and there is an abundance of literature on the subject of seismic engineering. In particular, the reader is referred to ASCE 4-98 [Ref 1], and its successor document ASCE/SEI 43-05 [Ref 2]. Although geared to seismic analysis of safety related nuclear structures, this publication offers good practical guidance that is generally applicable to seismic analysis.
Download or read book Application of the Finite Element Method to the Seismic Design and Analysis of Large Moment End plate Connections written by Timothy Wayne Mays and published by . This book was released on 2000 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to problems associated with welded moment connections uncovered after the Northridge earthquake, large bolted connections are becoming a much more attractive alternative for design in seismic regions. However, stringent design requirements established by the AISC Seismic Provisions for Structural Steel Buildings (1997) make current moment end-plate configurations and design procedures inadequate for multi-story buildings. This dissertation first examines and critiques current seismic design philosophies as applied to moment end-plate connections. Next, the finite element method is used to develop much-needed design procedures for large moment end-plate connections, and to improve the understanding of the role of geometric parameters (e.g., bolt pitch and stiffener locations) in the response of these connections. Finally, single-story and multi-story frames incorporating large moment end-plate connections with known moment-rotation characteristics are considered under seismic loading to determine the effectiveness of these systems in dissipating energy caused by the ground motion
Download or read book Application of the Finite Element Method to Multihull Ship Structural Analysis written by Paris Genalis and published by . This book was released on 1972 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Data Generation for Finite element Structural Analysis of Three dimensional Naval Ship Structures written by Paul M. Meyer and published by . This book was released on 1975 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computer program has been developed to automatically discretize three-dimensional structures consisting of combinations of cross-stiffened grillages. Discretizing is dividing a continuous structure into a number of connected parts so that the sum of the collection of parts equals the total structure. The purpose of this computer program is to shorten the preliminary work time involved in preparing data for analysis by the finite-element method. The grillages can have multiple openings with coamings, and the computer program can also generate the cards that describe inplane and normal uniform loads. Input to the program consists of punched cards which define structural geometry, boundary conditions, and loadings. Output consists of a disk file which can be read directly either by NASTRAN or by a special utility program to produce plots of the discretized structure. Access can also be obtained at a later time by a special purpose program which displays the discretized structure at an interactive graphics terminal. The validated data can then be made accessible to NASTRAN for a finite-element analysis. Modifications to this program will extend the current capability of the program for discretizing from simple warped surfaces to more complex curved surfaces and will allow use of the program on either a UNIVAC-1108 or an IBM-360/91 computer. (Author).
Download or read book Finite Element Response Sensitivity Probabilistic Response and Reliability Analyses of Structural Systems with Applications to Earthquake Engineering written by Michele Barbato and published by . This book was released on 2007 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: The geometric, mechanical, material and loading parameters used to define the mechanics-based finite element (FE) models of structural systems as well as their seismic input are characterized by significant uncertainties. The rational treatment of uncertainties in computational mechanics has been the object of increasing attention in recent years. Modern design codes indirectly account for parameter and model uncertainties in order to ensure satisfactory designs. Thus, in addition to accurate deterministic models, methods are needed to propagate uncertainties from the parameters defining the FE model of a structure to the engineering demand parameters. FE response sensitivities (RSs) to both model and loading parameters represent an essential ingredient in studying this complex uncertainty propagation. New RS algorithms based on the Direct Differentiation Method (DDM) are derived and implemented in general-purpose nonlinear structural analysis frameworks. The use of the DDM is extended to (1) force-based frame elements, (2) steel-concrete composite structures, and (3) three-field mixed FEs. In addition, the effects on RS continuity of using smooth versus non-smooth material constitutive models are thoroughly examined. An efficient simulation technique for an existing fully non-stationary stochastic earthquake ground motion model is developed. The definition of non-geometric spectral characteristics is extended to general complex-valued non-stationary stochastic processes. Closed-form approximate solutions of the first-passage problem are developed for single- and multi-degree-of-freedom linear elastic systems. First-order second-moment approximations of the first- and second-order statistics of the response of linear/nonlinear structural systems with random/uncertain parameters and subjected to quasi-static and/or dynamic load(s) are computed efficiently using DDM-based FE RSs. The probability of a structural response quantity exceeding a specified threshold level is obtained by using the First-Order Reliability Method in conjunction with the DDM-based FE RSs in the search for the Design Point(s) (DP). A new method, referred to as Multidimensional Visualization in the Principal Planes, is developed to explore the geometry of limit-state surfaces near the DP(s) in reduced-spaces defined by planes of major principal curvatures at the DP. A new hybrid reliability analysis method (DP search - Response Surface - Importance Sampling) is developed and tested. Based on pushover and time history analyses, examples of both time-invariant and time-variant reliability analysis of structural systems are presented to illustrate the probabilistic methods developed.
Download or read book Seismic Analysis of Concrete Structures written by Shivaji Eknath Jagtap and published by . This book was released on 2009 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: A full scale seven-story reinforced concrete building, was tested on a shake table, at the National Earthquake Engineering Society's (NEES) facility at the University of California, San Diego during the period October 2005 through January 2006 using scaled acceleration time histories of the 1994 Northridge Earthquake, one of the strongest recorded motions. Numerically calculated parameters using a three dimensional finite element model of this structure by using commercially available software SAP2000 are compared with available experimental data from tests with the goal to propose a type of analyses which can accurately estimate all the necessary parameters for structural engineering industry. The methods studies include equivalent lateral force method, modal response spectrum analysis and nonlinear time history analysis consisting of fast non linear analysis and direct integration analysis.
Download or read book Finite Element Analysis of Unanchored Structures Subjected to Seismic Excitation written by and published by . This book was released on 2004 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Finite Element Analysis of Drydocks and Waterfront Facilities A Technology Assessment written by and published by . This book was released on 1991 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Various models of Navy waterfront structures are presented and employed to assess their effectiveness in predicting the vulnerability of these systems to operational and earthquake loads. The emphasis is on application of three dimensional finite element models to reinforced concrete structural analysis. Results indicate that dynamic analysis is important in the calculation of the structural response of both a drydock and a blocked vessel in drydock. The primary natural frequencies and natural mode shapes for a drydock are longitudinal deformation modes which cannot be predicted by current methodology based upon statically equivalent analysis of two dimensional models. Further results from nonlinear analysis provide new insight into the behavior of the drydock/caisson seal for hydrostatic loads, which is dramatically different from that which underlies current design and maintenance procedures. Similarly, results from a three-dimensional nonlinear static analysis of a scale model of a reinforced concrete pier deck, subjected to punching shear failure loads, are shown to compare well with experimental data. Modern three-dimensional finite element technology is appropriate for analysis of waterfront structures.
Download or read book Mixed Formulation for Seismic Analysis of Composite Steel concete Frame Structures written by Ashraf Salah Eldin Ayoub and published by . This book was released on 1999 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Linear Structural Stress Analysis of a Hull Girder Penetration and a Short Longitudinal Bulkhead Using Finite Element Modeling written by Gregg W. Baumann and published by . This book was released on 1997 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this study is to investigate structural shadow zones encountered in shipbuilding design using the I-DEAS (Integrated Design Engineering Analysis Software) software. The term 'shadow zone' refers to areas of low stress concentrations that are caused by lines of stress bending around structural discontinuities. Two ship design situations frequently encountered that result in shadow zones are hull girder penetrations and short structural longitudinal bulkheads. In both of these situations, a long-used rule of thumb is to construct a line with a slope of 1:4 originating from the. discontinuity that encompasses the area of low stress. The material within this line is then considered ineffective when computing the section modulus. This can prove to be expensive. However, powerful finite element analysis software is readily available that can analyze the shadow zones in greater detail and possibly minimize the area considered ineffective. This study uses the I-DEAS software to develop finite element models of the cited design situations for a U.S. Navy Frigate, FFG-7 class of ship. It conducts a static structural linear analysis of the ship balanced on a trochoidal wave of height 1.1 VL. The results generated in this study validate the rule of thumb in both situations.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1989 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monthly Catalog of United States Government Publications written by and published by . This book was released on with total page 1386 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monthly Catalog of United States Government Publications written by United States. Superintendent of Documents and published by . This book was released on 1980 with total page 1232 pages. Available in PDF, EPUB and Kindle. Book excerpt: February issue includes Appendix entitled Directory of United States Government periodicals and subscription publications; September issue includes List of depository libraries; June and December issues include semiannual index
Download or read book Monthly Catalog of United States Government Publications Cumulative Index written by United States. Superintendent of Documents and published by . This book was released on 1976 with total page 1466 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monthly Catalogue United States Public Documents written by and published by . This book was released on 1980 with total page 1234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
