Evaluation on Environmental Corrosion Damage of Steel Domes

2010 ◽  
Vol 44-47 ◽  
pp. 163-167
Author(s):  
Bo Chen ◽  
Jian Feng Wei ◽  
Jin Zheng
Keyword(s):  
Natural Frequency ◽  
Corrosion Damage ◽  
Exponential Model ◽  
Nonlinear Static Analysis ◽  
Space Structures ◽  
Structural Members ◽  
Nonlinear Static ◽  
Corrosion Of Steel

The evaluation on environmental corrosion damage of steel domes is carried out in this study through an integration of knowledge in material science and structural analysis. The refined exponential model for estimating corrosion of steel materials is presented based on long-term experimental data available. The formula for relating structural natural frequency sensitivity to structural member thickness is then derived to assess the sensitivity of natural frequency to variation of member thickness due to corrosion. The nonlinear static analysis is conducted to evaluate effects of atmospheric corrosion on the stress of structural members and the safety of steel space structures. A real steel dome built in China is taken as the case study to examine the feasibility of the proposed approach and to assess the potential corrosion damage to the structure..

scholarly journals Technical-Economical Comparison Between Vertical Link Beam and Knee Brace Systems in Mid-Rise Steel Buildings

2019 ◽  
Vol 9 (1) ◽  
pp. 115-120
Author(s):  
Mahmoud Sadeghpour
Keyword(s):  
Lateral Displacement ◽  
Nonlinear Static Analysis ◽  
Structural Members ◽  
Braced Frames ◽  
Steel Buildings ◽  
Base Shear ◽  
Knee Brace ◽  
Normal Period ◽  
Nonlinear Static ◽  
Shear Panel

Abstract In knee brace and shear panel systems, unlike eccentric braced frames, energy absorption is achieved through plastic deformation when sub-members yield by shear forces or bending moments caused by bracing members during severe earthquakes. Several studies have been conducted on the behavior of these two systems which resulted in design methods to obtain the best structural performance. The present study attempted to design frames using these methods, and then to compare them in terms of technical and economic factors. In this regard, to obtain a pattern of the frames behavior, a 3-span 5-storey frame was modeled for three different types of brace system (coaxial, knee and shear panel) using ANSYS software. After performing pushover nonlinear static analysis, behavior coefficients were determined and the force-lateral displacement curves of the systems were compared. In the next step, 3-span 5- 8- and 12-storey frames were analyzed and designed using ETABS software and were compared in terms of the parameters such as relative lateral displacement, normal period of system, structural weight, and shear force into foundation. The results indicate that using the above-mentioned systems, structure will exhibit more ductility which leads to reduced design base shear. The forces applied to main structural members (beams, columns, and braces) are reduced by the use of knee brace and shear panel systems. This will affect the design and sometimes increases or decreases weight of these members.

scholarly journals Analysis of second order effects: case study

2016 ◽  
Vol 9 (4) ◽  
pp. 494-501
Author(s):  
J. R. BUENO ◽  
D. D. LORIGGIO
Keyword(s):  
Stiffness Matrix ◽  
Second Order ◽  
Nonlinear Static Analysis ◽  
Order Effects ◽  
Combined Effects ◽  
Geometrical Configuration ◽  
Geometric Stiffness ◽  
Plane Frame ◽  
Nonlinear Static

Abstract This paper presents a nonlinear static analysis of a reinforced concrete plane frame. It has as main objective is to realize a global stability verification of a plane frame, by using geometric stiffness matrix. In order to obtain first and second order combined effects, equilibrium and kinematic relations were studied in the deformed geometric configuration. These results were obtained by using geometric stiffness matrix and multiplying horizontal forces by Gamma-Z coefficient. Both procedures disclosed very similar results in the study, indicating that Gamma-Z can be used to study equilibrium and kinematic relations in deformed geometrical configuration of the structure.

An Investigation on Nonlinear Effects of Gaps in Dolphin Structures Analysis

2010 ◽  
Author(s):  
Mohammad Reza Moharrami ◽  
Ehssan Zargar ◽  
Mahdi Mirzaei
Keyword(s):  
Static Analysis ◽  
Nonlinear Effects ◽  
Nonlinear Static Analysis ◽  
Force Transmission ◽  
Box Girder ◽  
Finite Element Software ◽  
Nonlinear Static ◽  
Pass Through ◽  
The Persian Gulf

Dolphins are essential structures used in gas and oil terminals for berthing and mooring purposes. In essence, design of these structures is mostly based on linear analysis, so that the effect of nonlinearity on the actual responses is not considered. In this paper, the effect of nonlinearity caused by the gap modeling between parts of the structure is investigated and the modeling is carried out using accurate and efficient finite element software. As a case study, a mooring dolphin located in the Persian Gulf is simulated in order to demonstrate the nonlinear analysis effects. In contrary to the most common mooring dolphins, the dolphin is designed to have flexible structural behavior. As a result, it is comprised of three short piles connected by a triangle-shape box girder from the top. The box girder is composed of two triangle plates as flanges, which are connected by means of vertical stiffeners acting as web. Besides, three torsion bars are used to change the direct shear to a torsion shear to get a more efficient force transmission. In the piles-box girder connection, where piles pass through the holes prepared in the flanges, there is a considerable difference between the diameter of piles and holes as a tolerance (gap) for construction and codes provisions (BS 6349). The nonlinear effects are mainly caused by the gap in this connection besides the vertical supports of the box girder and the torsion bars. This paper contains the results of a nonlinear static analysis in which the gap between different parts is modeled using nonlinear spring elements to reach a convergence in solving the equations. Results are then compared with the linear static analysis of a similar dolphin, which gaps are not modeled in it and nonlinear effects are presented.

scholarly journals Seismic Assessment of Steel MRFs by Cyclic Pushover Analysis

2019 ◽  
Vol 13 (1) ◽  
pp. 12-26 ◽  
Author(s):  
F. Barbagallo ◽  
M. Bosco ◽  
A. Ghersi ◽  
E.M. Marino ◽  
P.P. Rossi
Keyword(s):  
Local Level ◽  
Pushover Analysis ◽  
Nonlinear Dynamic Analysis ◽  
Structural Response ◽  
Strength Degradation ◽  
Structural Members ◽  
Seismic Behaviour ◽  
Ground Acceleration ◽  
Nonlinear Static

Background:Structural members subjected to strong earthquakes undergo stiffness and strength degradation. To predict accurately the seismic behaviour of structures, nonlinear static methods of analysis have been developed in scientific literature. Generally, nonlinear static methods perform the pushover analysis by applying a monotonic lateral load. However, every earthquake input is characterized by several repeated loads with reverse in signs and the strength and deformation capacities of structures are generally related to the cumulative damage. This aspect is neglected by the conventional monotonic approaches, which tend to overestimate the strength and stiffness of structural members.Objective:This paper aims to investigate the possibility that the Cyclic Pushover Analysis (CPA) may be used as a tool to assess the seismic behaviour of structures. During the CPA, the structure is subjected to a distribution of horizontal forces that is reversed in sign when predefined peak displacements of the reference node are attained. This process repeats in cycles previously determined in a loading protocol.Methods:To investigate the effectiveness of the CPA in predicting the structural response, a steel moment resisting frame is designed as a case study building. A numerical model of this frame is developed in OpenSees. To examine the influence of the loading protocols on the seismic response, the CPA is run following the ATC-24 and the SAC protocols. Additionally, the seismic demand of the case study frame is determined by a Monotonic Pushover Analysis (MPA) and by Incremental nonlinear Dynamic Analysis (IDA).Results and Conclusions:The following results are obtained:• Despite the differences between the SAC and the ATC-24 loading protocols, the CPA applied according to those two protocols led to almost the same structural response of the case study frame.• The CPA showed the capability of catching the stiffness and strength degradation, which is otherwise neglected by the MPA. In fact, given a base shear or peak ground acceleration, the CPA leads to the estimation of larger displacement demands compared to the MPA.• During long (or medium) duration earthquakes, the CPA was necessary to estimate accurately the response of the structure. In fact, at a PGA equal to 1 g, the CPA estimated the top displacement demand with an error lower than 10%, while the MPA underestimated it by 18%.• The importance of considering the cyclic deterioration is shown at local level by the damage indexes of the frame. In the case of long earthquakes, given a top displacement of 600 mm (corresponding to a PGA equal to 1 g), the CPA estimated the damage indexes with an error equal to 12%.

scholarly journals INFLUENCE OF APPLICATION OF SANDWICH PANEL ON STATIC AND DYNAMIC BEHAVIOUR OF FERRY RO-RO RAMP DOOR

2020 ◽  
pp. 1-9
Author(s):  
Tuswan Tuswan ◽  
Achmad Zubaydi ◽  
Bambang Piscesa ◽  
Abdi Ismail ◽  
Muhammad Fathi Ilham ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Natural Frequency ◽  
Static Analysis ◽  
Sandwich Panel ◽  
Weight Ratio ◽  
Free Vibration Analysis ◽  
Nonlinear Static Analysis ◽  
Damage Area ◽  
Finite Element Software ◽  
Nonlinear Static

The implementation of sandwich panel on the marine structure needs better knowledge of mechanical behaviour, primarily static and dynamic response. The static and dynamic response is investigated due to the application of a sandwich panel on the ferry ro-ro ramp door using finite element software ABAQUS. Five modification models using different sandwich thickness and stiffener configuration are compared using nonlinear static analysis to analyse a comparison of structural strength and weight saving. Additionally, the dynamic response is also investigated due to debonding problem. The influence of debonding ratio, geometry, number of debonding, debonding depth, debonding location, and boundary condition is carried out. Debonding is estimated by using free vibration analysis where Lanczos method for eigenvalues extraction is applied. Result of nonlinear static analysis shows that Model C causes an increase in strength to weight ratio compared to the existing model. Furthermore, natural frequencies are being calculated as modal parameters to investigate the debonding problem. The natural frequency of the debonded model decreases due to discontinuity in the damage area. The dynamic response using natural frequency shift can be performed as structural health monitoring technique on the ramp door model.

Studies on VIV Fatigue Behavior in SCRS of Hybrid Riser Systems

2002 ◽  
Author(s):  
Luciano Tardelli Vieira ◽  
Breno Pinheiro Jacob ◽  
Antonio Carlos Fernandes ◽  
Ricardo Franciss
Keyword(s):  
Fatigue Behavior ◽  
Fatigue Behaviour ◽  
Nonlinear Static Analysis ◽  
Practical Case ◽  
Analysis Methodology ◽  
Campos Basin ◽  
Steel Catenary Risers ◽  
Numerical Tools ◽  
Nonlinear Static

The main objective of this work is to demonstrate the application of an analysis methodology for hybrid riser configurations. Such configurations are based on submerged buoys that are connected by jumpers to a floating production unit (a FPSO vessel for instance), and by risers to the seabottom. The focus is on VIV-induced fatigue behavior of the steel catenary risers that connect the buoy to the seabottom. The methodology employs numerical tools for the nonlinear static analysis, modal analysis, VIV and fatigue behaviour. The application of the methodology is illustrated with the analysis of a practical case study located in Campos Basin.

Caregivers' Perceptions of Speech-Language Pathologist Talk About Child Language and Literacy Disorders

2020 ◽  
Vol 29 (4) ◽  
pp. 2049-2067
Author(s):  
Karmen L. Porter ◽  
Janna B. Oetting ◽  
Loretta Pecchioni
Keyword(s):  
Language And Literacy ◽  
Collective Case Study ◽  
Study Approach ◽  
School Aged Children ◽  
Speech Language Pathologist ◽  
Therapy Goals ◽  
Semistructured Interviews ◽  
Types Of Information

Purpose This study examined caregiver perceptions of their child's language and literacy disorder as influenced by communications with their speech-language pathologist. Method The participants were 12 caregivers of 10 school-aged children with language and literacy disorders. Employing qualitative methods, a collective case study approach was utilized in which the caregiver(s) of each child represented one case. The data came from semistructured interviews, codes emerged directly from the caregivers' responses during the interviews, and multiple coding passes using ATLAS.ti software were made until themes were evident. These themes were then further validated by conducting clinical file reviews and follow-up interviews with the caregivers. Results Caregivers' comments focused on the types of information received or not received, as well as the clarity of the information. This included information regarding their child's diagnosis, the long-term consequences of their child's disorder, and the connection between language and reading. Although caregivers were adept at describing their child's difficulties and therapy goals/objectives, their comments indicated that they struggled to understand their child's disorder in a way that was meaningful to them and their child. Conclusions The findings showed the value caregivers place on receiving clear and timely diagnostic information, as well as the complexity associated with caregivers' understanding of language and literacy disorders. The findings are discussed in terms of changes that could be made in clinical practice to better support children with language and literacy disorders and their families.

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