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Building Design
Published in P.E. Tim Huff, A Practical Course in Advanced Structural Design, 2021
AISC 360-16 Appendix 1 permits design by inelastic analysis in certain cases for steel building members. Four criteria must be satisfied in order for inelastic analysis to be permissible (see AISC 360-16 A1.3.2). The specified minimum yield strength, Fy, of members subject to plastic hinging may not exceed 65 ksi.The cross section of members subject to plastic hinging must qualify not as compact but as “ductile-compact.”The unbraced length of members subject to plastic hinging is limited not to Lp as is the case for conventional design but to Lpd.The axial force in members subject to plastic hinging must not exceed 0.75FyAg.
Construction and Materials Defect
Published in Mavis Sika Okyere, Mitigation of Gas Pipeline Integrity Problems, 2020
This is usually expressed as a percentage of the specified minimum yield strength (SMYS) for the pipeline steel. It has been shown that the boundary between arrest and propagation in brittle fractures is dependent on the operating temperature and the energy stored within the pipe material, i.e. the hoop stress. Therefore, it would seem appropriate to specify the design factor at a level which takes into consideration the boundary between defect arrest and propagation, also known as the leak/break boundary. Obviously not all defects behave in the same way; their behavior depends on the length, depth, and size of the pipe, and therefore some method of correlating these parameters is required. Figure 4.2 shows the results of a large number of tests carried out by British Gas. The results are plotted as the percentage of SMYS at failure against a defect length factor (which does include depth) for both corrosion defects and artificially induced defects. The leak/break boundary is clearly evident in each case and shows that the mechanically induced defects fail at a lower stress level than corrosion defects; these are therefore the controlling influence on design. It should also be noted that there are no breaks below 30% SMYS, and therefore a design factor of 0.3 would ensure a break-free pipeline under most circumstances.
Steel–Concrete Composite Box Girder Bridges
Published in Wai-Fah Chen, Lian Duan, Bridge Engineering Handbook, 2019
where bf is full width of steel flange and Fys is specified minimum yield strength of stiffener. Try stiffener width, bt= 180.0 mm. bt=180>{50+d30=50+160030=103.3mm0.25bf=0.25(450)=112.5mm
Prolonging the Lifetime of Old Steel and Steel–Concrete Bridges: Assessment Procedures and Retrofitting Interventions
Published in Structural Engineering International, 2019
Alessio Pipinato, Peter Collin, Robert Hallmark
Both ASTM A3709 and Eurocode EN 6892-110 define the testing requirements to determine the tensile strength of steel products. The test method requires the determination of the yield strength, tensile strength and percentage elongation for each test. A stress–strain curve can be measured by graphically or digitally recording the load and elongation of an extensometer during the duration of the test. The elastic modulus or Young's modulus for steel is the slope of the elastic portion of the stress–strain curve. It is conservatively taken as E = 200 000 MPa for structural calculations for all structural steel used in bridge construction. Furthermore, minimum ductility is required for steel, which should be expressed in terms of limits for the following: the ratio fu/fy of the specified minimum ultimate tensile strength fu to the specified minimum yield strength fythe elongation at failure on a specific gauge lengththe ultimate strain εu, corresponding to the ultimate strength fu.
Model for remaining strength estimation of a corroded pipeline with interacting defects for oil and gas operations
Published in Cogent Engineering, 2019
K.U. Amandi, E.O. Diemuodeke, T.A. Briggs
where σs is specified minimum yield strength of the pipe, t is pipe thickness, D is external diameter of the pipe, d is depth of corrosion defect and is longitudinal length.
Dynamic reliability analysis for residual life assessment of corroded subsea pipelines
Published in Ships and Offshore Structures, 2021
Reza Aulia, Henry Tan, Srinivas Sriramula
Pipeline residual life based on calculated corrosion rate in the previous section is compared with the residual life result calculated by operator’s assessment method. This is to check the reliability of the proposed dynamic Bayesian network-based framework when it is applied to the industrial data. As an example, this section will present the pipeline-1 residual life calculation using the operator’s method, which starts with the corrosion rate calculation based on inspection report using the following formula: where CR is the pipeline corrosion rate, tnominal is the nominal thickness (12.7 mm), tactual is the thickness from inspection report (12 mm), 1.125 is the qualitative safety factor and T is the time interval between the commission or previous inspection time and the current inspection time (15 years). After that, the corrosion prediction CRmin/max is calculated by multiplying the CR with the corrosion rate factor, which ranges from 1.5 to 2.3 (Rifandi 2017). Remaining thickness determination at end of service year (tend) is calculated as where RSL is the remaining service life of the pipeline (20 years). Maximum allowable operating pressure (MAOP) can be given as where F is the design factor, 0.6 for riser and 0.72 for pipeline, E is the longitudinal weld-joint factor (1), S is the specified minimum yield strength (52000 psi), D is the outside diameter of the pipeline (219.08 mm), and FCA is the future corrosion allowance, which is calculated by multiplying the CRmin/max with the inspection interval (5 years). It is observed that the recommended operating pressure for the chosen pipeline is below 1734.60 psi, while the operating pressure is 650 psi (4.5 MPa). The pipeline residual life is determined by calculating the minimum required thickness of the pipeline (trequired) as Pipeline residual life (RL) can be calculated as The result from the above method can be compared with the pipeline residual life based on dynamic Bayesian network corrosion rate analysis. From the Bayesian probability updating in Section 4.1, corrosion rate probability distributions are converted to pipeline residual life for each state using equation 8. The obtained residual life based on estimated corrosion rate for pipeline-1, pipeline-2 and pipeline-3 is presented in Figure 12.