The Experts below are selected from a list of 6180 Experts worldwide ranked by ideXlab platform
Alain Nussbaumer - One of the best experts on this subject based on the ideXlab platform.
-
on the low cycle fatigue capacity of unanchored steel liquid storage Tank Shell to base connections
Bulletin of Earthquake Engineering, 2012Co-Authors: Gary Scott Prinz, Alain NussbaumerAbstract:Under strong earthquake motions, the liquid stored within large unanchored steel Tanks can cause rocking and uplift of the Tank base from the supporting foundation. Repeated rocking can lead to low-cycle fatigue fractures in the Tank base-plate, and ultimately spillage of Tank contents. Due to limited research on Tank connection capacity, current European and New Zealand Tank standards (EuroCode8 part 4 and NZSEE) impose unjustified rotation limits on Tank Shell-to-base connections (current limit being 0.2 rad). These rotation limits often govern the design of new Tanks, and many existing Tanks require retrofit to meet compliance. This paper experimentally investigates the fatigue capacity of Tank Shell-to-base connections, with a focus on the effects from material ductility and applied strain range (rotation range). Twenty-seven Tank connections representing two steel material grades are fatigue tested under constant range rotation cycles to generate fatigue-life curves. Tensile loads applied to the base-plate simulate membrane action present in Tanks during uplift. Results indicate that the strain capacity of the base-plate base material strongly influences connection fatigue capacity as fatigue fractures originate in the base material away from the weld toe and weld heat affected zone. Increasing base-plate ductility drastically increases connection fatigue life. All connection specimens sustained multiple uplift cycles at rotations greater than the existing EuroCode8 and NZSEE limits.
-
on the low cycle fatigue capacity of unanchored steel liquid storage Tank Shell to base connections
Bulletin of Earthquake Engineering, 2012Co-Authors: Gary Scott Prinz, Alain NussbaumerAbstract:Under strong earthquake motions, the liquid stored within large unanchored steel Tanks can cause rocking and uplift of the Tank base from the supporting foundation. Repeated rocking can lead to low-cycle fatigue fractures in the Tank base-plate, and ultimately spillage of Tank contents. Due to limited research on Tank connection capacity, current European and New Zealand Tank standards (EuroCode8 and NZSEE) impose unjustified rotation limits on Tank Shell-to-base connections (current limit being 0.2rad). These rotation limits often govern the design of new Tanks, and many existing Tanks require retrofit to meet compliance. This paper experimentally investigates the fatigue capacity of Tank Shell-to-base connections, with a focus on the effects from material ductility and applied strain range (rotation range). Twenty-seven Tank connections representing two steel material grades are fatigue tested under constant range rotation cycles to generate fatigue-life curves. Tensile loads applied to the base-plate simulate membrane action present in Tanks during uplift. Results indicate that the strain capacity of the base-plate base material strongly influences connection fatigue capacity as fatigue fractures originate in the base material away from the weld toe and weld HAZ. Increasing base-plate ductility drastically increases connection fatigue life. All connection specimens sustained multiple uplift cycles at rotations greater than the existing EuroCode8 and NZSEE limits.
-
fatigue analysis of liquid storage Tank Shell to base connections under multi axial loading
Engineering Structures, 2012Co-Authors: Gary Scott Prinz, Alain NussbaumerAbstract:During severe seismic events the base of unanchored steel liquid-storage Tanks can uplift, causing large inelastic rotation demands at the Shell-to-base connections and large multi-axial stresses (radial tension and circumferential compression) in the Tank base-plate. With repeated cycles of uplift, these Shell-to-base connections are susceptible to low-cycle fatigue failure. Limited research exists on the rotation capacity of Shell-to-base connections, and the studies that have been conducted have neglected the multi-axial stress states in the Tank base-plate. In this paper, an analytical study is conducted to determine the effects of these multi-axial base-plate stresses on the rotation capacity of Tank Shell-to-base connections. Modeling methods and a low-cycle fatigue failure criterion are validated using experimental results, and then twenty-three models with varying multi-axial stress states are analyzed under various ranges of cyclic rotation. Results indicate that moderate levels of base-plate radial tension and circumferential compression (between 10 and 20%y) can significantly reduce connection rotation capacity (between 28-48%). Additionally, due to increased yielding from circumferential stresses at low rotations, smaller uplift cycles may contribute more to failure than previously reported in studies neglecting base-plate multi-axial stress-states. Indicated rotation capacities are larger than current code limits.
-
seismic performance of unanchored liquid storage Tank Shell to base connections phase 2
2012Co-Authors: Gary Scott Prinz, Alain NussbaumerAbstract:Keywords: Unanchored Tanks, experimental testing, low-cycle fatigue, dynamic analysis Reference EPFL-REPORT-174640 Record created on 2012-02-02, modified on 2016-08-09
Gary Scott Prinz - One of the best experts on this subject based on the ideXlab platform.
-
on the low cycle fatigue capacity of unanchored steel liquid storage Tank Shell to base connections
Bulletin of Earthquake Engineering, 2012Co-Authors: Gary Scott Prinz, Alain NussbaumerAbstract:Under strong earthquake motions, the liquid stored within large unanchored steel Tanks can cause rocking and uplift of the Tank base from the supporting foundation. Repeated rocking can lead to low-cycle fatigue fractures in the Tank base-plate, and ultimately spillage of Tank contents. Due to limited research on Tank connection capacity, current European and New Zealand Tank standards (EuroCode8 part 4 and NZSEE) impose unjustified rotation limits on Tank Shell-to-base connections (current limit being 0.2 rad). These rotation limits often govern the design of new Tanks, and many existing Tanks require retrofit to meet compliance. This paper experimentally investigates the fatigue capacity of Tank Shell-to-base connections, with a focus on the effects from material ductility and applied strain range (rotation range). Twenty-seven Tank connections representing two steel material grades are fatigue tested under constant range rotation cycles to generate fatigue-life curves. Tensile loads applied to the base-plate simulate membrane action present in Tanks during uplift. Results indicate that the strain capacity of the base-plate base material strongly influences connection fatigue capacity as fatigue fractures originate in the base material away from the weld toe and weld heat affected zone. Increasing base-plate ductility drastically increases connection fatigue life. All connection specimens sustained multiple uplift cycles at rotations greater than the existing EuroCode8 and NZSEE limits.
-
on the low cycle fatigue capacity of unanchored steel liquid storage Tank Shell to base connections
Bulletin of Earthquake Engineering, 2012Co-Authors: Gary Scott Prinz, Alain NussbaumerAbstract:Under strong earthquake motions, the liquid stored within large unanchored steel Tanks can cause rocking and uplift of the Tank base from the supporting foundation. Repeated rocking can lead to low-cycle fatigue fractures in the Tank base-plate, and ultimately spillage of Tank contents. Due to limited research on Tank connection capacity, current European and New Zealand Tank standards (EuroCode8 and NZSEE) impose unjustified rotation limits on Tank Shell-to-base connections (current limit being 0.2rad). These rotation limits often govern the design of new Tanks, and many existing Tanks require retrofit to meet compliance. This paper experimentally investigates the fatigue capacity of Tank Shell-to-base connections, with a focus on the effects from material ductility and applied strain range (rotation range). Twenty-seven Tank connections representing two steel material grades are fatigue tested under constant range rotation cycles to generate fatigue-life curves. Tensile loads applied to the base-plate simulate membrane action present in Tanks during uplift. Results indicate that the strain capacity of the base-plate base material strongly influences connection fatigue capacity as fatigue fractures originate in the base material away from the weld toe and weld HAZ. Increasing base-plate ductility drastically increases connection fatigue life. All connection specimens sustained multiple uplift cycles at rotations greater than the existing EuroCode8 and NZSEE limits.
-
fatigue analysis of liquid storage Tank Shell to base connections under multi axial loading
Engineering Structures, 2012Co-Authors: Gary Scott Prinz, Alain NussbaumerAbstract:During severe seismic events the base of unanchored steel liquid-storage Tanks can uplift, causing large inelastic rotation demands at the Shell-to-base connections and large multi-axial stresses (radial tension and circumferential compression) in the Tank base-plate. With repeated cycles of uplift, these Shell-to-base connections are susceptible to low-cycle fatigue failure. Limited research exists on the rotation capacity of Shell-to-base connections, and the studies that have been conducted have neglected the multi-axial stress states in the Tank base-plate. In this paper, an analytical study is conducted to determine the effects of these multi-axial base-plate stresses on the rotation capacity of Tank Shell-to-base connections. Modeling methods and a low-cycle fatigue failure criterion are validated using experimental results, and then twenty-three models with varying multi-axial stress states are analyzed under various ranges of cyclic rotation. Results indicate that moderate levels of base-plate radial tension and circumferential compression (between 10 and 20%y) can significantly reduce connection rotation capacity (between 28-48%). Additionally, due to increased yielding from circumferential stresses at low rotations, smaller uplift cycles may contribute more to failure than previously reported in studies neglecting base-plate multi-axial stress-states. Indicated rotation capacities are larger than current code limits.
-
seismic performance of unanchored liquid storage Tank Shell to base connections phase 2
2012Co-Authors: Gary Scott Prinz, Alain NussbaumerAbstract:Keywords: Unanchored Tanks, experimental testing, low-cycle fatigue, dynamic analysis Reference EPFL-REPORT-174640 Record created on 2012-02-02, modified on 2016-08-09
Howard K Yue - One of the best experts on this subject based on the ideXlab platform.
-
steel storage Tank Shell settlement assessment based on finite element and api standard 653 analyses
2008 7th International Pipeline Conference Volume 1, 2008Co-Authors: Mohamed R Chebaro, Nade Yoosefghodsi, Howard K YueAbstract:API Standard 653 addresses issues related to the inspection, repair, alteration and reconstruction of steel storage Tanks built according to API Standard 650 or API 12C to help maintain Tank integrity. Although the standard covers three types of Tank settlement, namely edge, bottom and Shell, this paper focuses on the assessment of Shell settlement. It also provides a comparison between an analytical model based on API Standard 653 and a finite element analysis (FEA) model that replicates field operating loading and settlement conditions of storage Tanks. A basis for comparison between both models was established from the maximum allowable settlement and strain values. Several scenarios were generated using actual field data collected from steel storage Tanks located in Alberta to illustrate the correlation between the two models. Specific information on the storage Tanks under consideration cannot be disclosed for confidentiality reasons.Copyright © 2008 by ASME
Moras B. - One of the best experts on this subject based on the ideXlab platform.
-
Explosion of fixed roof atmospheric storage Tanks, part 3 Gas explosion and structural response simulations
'Wiley', 2012Co-Authors: Taveau J., Moras B.Abstract:International audienceMany flammable products are stored in large Tanks at atmospheric pressure. Ignition of a hydrocarbon-air mixture in such Tanks can lead to an explosion and cause lethal casualties or damage the surrounding facilities and buildings. To apprehend this, safety distances for humans, structures, and equipments need to be defined. Several simple methodologies have been set up to estimate safety distances in case of an atmospheric storage Tank explosion. This third and last article concerning fixed roof atmospheric storage Tank explosions focuses on numerical modeling, including gas explosion and structural response simulations. Three-dimensional gas explosion simulations using the CFD code FLACS have been performed to define a typical pressure load profile to apply on the inner side of the Tank Shell. Then, the structural response of the Tank (deformation and displacement), under the loading conditions previously obtained, has been computed with LS-DYNA. Consequently, the findings question some of the assumptions used in analytical methods described previously. The specific input data needed to obtain a reasonably conservative estimation of the safety distances have been identified. © 2011 American Institute of Chemical Engineers
B. Moras - One of the best experts on this subject based on the ideXlab platform.
-
explosion of fixed roof atmospheric storage Tanks part 3 gas explosion and structural response simulations
Process Safety Progress, 2012Co-Authors: J. Taveau, B. MorasAbstract:Many flammable products are stored in large Tanks at atmospheric pressure. Ignition of a hydrocarbon–air mixture in such Tanks can lead to an explosion and cause lethal casualties or damage the surrounding facilities and buildings. To apprehend this, safety distances for humans, structures, and equipments need to be defined. Several simple methodologies have been set up to estimate safety distances in case of an atmospheric storage Tank explosion. This third and last article concerning fixed roof atmospheric storage Tank explosions focuses on numerical modeling, including gas explosion and structural response simulations. Three-dimensional gas explosion simulations using the CFD code FLACS have been performed to define a typical pressure load profile to apply on the inner side of the Tank Shell. Then, the structural response of the Tank (deformation and displacement), under the loading conditions previously obtained, has been computed with LS–DYNA. Consequently, the findings question some of the assumptions used in analytical methods described previously. The specific input data needed to obtain a reasonably conservative estimation of the safety distances have been identified. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2012
