Papers by Mohinuddin Ahmed
Volume 8: Seismic Engineering, 2017
Piping systems of energy industries in oil & gas play a critical role in meeting the increasing g... more Piping systems of energy industries in oil & gas play a critical role in meeting the increasing global energy demand. A great portion of these pipelines is located in high seismic-prone areas. Such systems have been found to be quite vulnerable to seismic events. Current seismic design approaches to piping systems are mainly based on the allowable stress method, even though more modern design methods are currently available for buildings or nuclear power plants; for example, the Performance-Based Earthquake Engineering (PBEE) framework has not been applied yet to piping systems and relevant structures. In this respect, both information about the quantification of limit states for pipes and adequate non-linear structural models for seismic analysis of piping systems and relevant structures are very limited. One of the key ingredients of PBEE approach for the assessment of the seismic vulnerability of existing structures is the evaluation of fragility curves, namely the probability of...
Piping systems of energy industries in oil & gas play a critical role in meeting the increasing g... more Piping systems of energy industries in oil & gas play a critical role in meeting the increasing global energy demand. A great portion of these pipelines is located in high seismic-prone areas. Such systems have been found to be quite vulnerable to seismic events. Current seismic design approaches to piping systems are mainly based on the allowable stress method, even though more modern design methods are currently available for buildings or nuclear power plants; for example, the Performance-Based Earthquake Engineering (PBEE) framework has not been applied yet to piping systems and relevant structures. In this respect, both information about the quantification of limit states for pipes and adequate non-linear structural models for seismic analysis of piping systems and relevant structures are very limited.
Assessment of liquefaction susceptibility is essential for seismically active area when pile
foun... more Assessment of liquefaction susceptibility is essential for seismically active area when pile
foundations are designed or existing under seismic loading. During the liquefaction soil loss
its strength and stiffness, thus remove the support from pile that can affect the overall
stability of the pile foundations. The main objective of this study is to investigate the extent
of the liquefaction zone that will make unsupported to pile and to assess the effect of the
liquefaction on the pile considering structural and geotechnical aspects. The simplified
empirical procedure of Seed & Idriss based on standard penetration test, liquefaction of soil is
predicted. Besides, a simple approach of Euler load to predict the buckling capacity of an
axially loaded partially embedded pile in sand is formulated using the conventional Davisson
and Robinson method combined with the ACI & area transform theory’s flexural stiffness
equation of the slender concrete column. Example solved as a case study based on above
analytical procedures that an axially loaded existing concrete pile under foundation can be
laterally unsupported in liquefied soils and susceptible to buckling failure and pointer towards
the inclusion of slenderness ratio limit of pile in the respective building code.
Urban earthquake vulnerability assessment of
existing buildings is essential to local authorities... more Urban earthquake vulnerability assessment of
existing buildings is essential to local authorities. An efficient
tool to assess the seismic vulnerability of existing buildings is
also an important factor for planning urban/regional-scale
emergency response and earthquake protection/retrofitting
schemes to protect human lives, economy .This paper presents
a methodology to predict the seismic vulnerability of buildings
by key statistical analysis using GIS (Geographic Information
System) based on a number of structural parameters that
determined on the basis of engineering knowledge and
observations. Building inventory survey chosen as a method
for rapid visual screening during field survey to collect data
for statistical analysis. In this case study, seismic vulnerability
assessment of buildings is carried out for the city Cox’s Bazar,
situated on the bank of the Bay of Bengal, the main tourist’s
city of Bangladesh. The assessment showed seismic
vulnerability factors recognized with heavy overhanging
(26%), absent of basement (25%), pounding possibility (14%),
plan irregularities (12%) and soft storey (7%).It is also
observed that if one of the soft storey buildings under
liquefaction fail which will affect the others very easily
because all the building structure are very close to each other.
Drafts by Mohinuddin Ahmed
Despite of vast advanced in finite element method (FEM) to model structural member behavior, stil... more Despite of vast advanced in finite element method (FEM) to model structural member behavior, still there are many issues remain open, which need to solve and development is under process. Thus, a sophisticated numerical tool and method (like FEM) should have evolved to a certain level where they can use with confidence in seismic risk assessment as well as computationally economic and less time consuming. In this line, this study start with comprises parameter assessment of elbow, based on available element types in general FEM software like Sap2000 and variation of geometry property , to understand the structural characteristic response as a component of curved pipe during modelling. The picture of the study is draw that there are exist inconsistency regarding the reality and accuracy of structural behavior and pointed towards the further development in modelling issue. Onwards, a simple tool or parameter proposed and integrated with 3D-FEM modelling of elbow in OpenSees environment through an equivalent beam for predicting the nonlinear behavior of steel pipe elbow under strong cyclic loading and validate by experimental test. This equivalent beam has the potential of considering axial, bending and torsion degrees of freedom simultaneously, and it facilitates the interaction between the elbow and the rest of the piping system. This tool can apply with any given geometry property of elbow in 3D-FEM modelling and the model size will be reduced by at least in compare to a shell element model..
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Papers by Mohinuddin Ahmed
foundations are designed or existing under seismic loading. During the liquefaction soil loss
its strength and stiffness, thus remove the support from pile that can affect the overall
stability of the pile foundations. The main objective of this study is to investigate the extent
of the liquefaction zone that will make unsupported to pile and to assess the effect of the
liquefaction on the pile considering structural and geotechnical aspects. The simplified
empirical procedure of Seed & Idriss based on standard penetration test, liquefaction of soil is
predicted. Besides, a simple approach of Euler load to predict the buckling capacity of an
axially loaded partially embedded pile in sand is formulated using the conventional Davisson
and Robinson method combined with the ACI & area transform theory’s flexural stiffness
equation of the slender concrete column. Example solved as a case study based on above
analytical procedures that an axially loaded existing concrete pile under foundation can be
laterally unsupported in liquefied soils and susceptible to buckling failure and pointer towards
the inclusion of slenderness ratio limit of pile in the respective building code.
existing buildings is essential to local authorities. An efficient
tool to assess the seismic vulnerability of existing buildings is
also an important factor for planning urban/regional-scale
emergency response and earthquake protection/retrofitting
schemes to protect human lives, economy .This paper presents
a methodology to predict the seismic vulnerability of buildings
by key statistical analysis using GIS (Geographic Information
System) based on a number of structural parameters that
determined on the basis of engineering knowledge and
observations. Building inventory survey chosen as a method
for rapid visual screening during field survey to collect data
for statistical analysis. In this case study, seismic vulnerability
assessment of buildings is carried out for the city Cox’s Bazar,
situated on the bank of the Bay of Bengal, the main tourist’s
city of Bangladesh. The assessment showed seismic
vulnerability factors recognized with heavy overhanging
(26%), absent of basement (25%), pounding possibility (14%),
plan irregularities (12%) and soft storey (7%).It is also
observed that if one of the soft storey buildings under
liquefaction fail which will affect the others very easily
because all the building structure are very close to each other.
Drafts by Mohinuddin Ahmed
foundations are designed or existing under seismic loading. During the liquefaction soil loss
its strength and stiffness, thus remove the support from pile that can affect the overall
stability of the pile foundations. The main objective of this study is to investigate the extent
of the liquefaction zone that will make unsupported to pile and to assess the effect of the
liquefaction on the pile considering structural and geotechnical aspects. The simplified
empirical procedure of Seed & Idriss based on standard penetration test, liquefaction of soil is
predicted. Besides, a simple approach of Euler load to predict the buckling capacity of an
axially loaded partially embedded pile in sand is formulated using the conventional Davisson
and Robinson method combined with the ACI & area transform theory’s flexural stiffness
equation of the slender concrete column. Example solved as a case study based on above
analytical procedures that an axially loaded existing concrete pile under foundation can be
laterally unsupported in liquefied soils and susceptible to buckling failure and pointer towards
the inclusion of slenderness ratio limit of pile in the respective building code.
existing buildings is essential to local authorities. An efficient
tool to assess the seismic vulnerability of existing buildings is
also an important factor for planning urban/regional-scale
emergency response and earthquake protection/retrofitting
schemes to protect human lives, economy .This paper presents
a methodology to predict the seismic vulnerability of buildings
by key statistical analysis using GIS (Geographic Information
System) based on a number of structural parameters that
determined on the basis of engineering knowledge and
observations. Building inventory survey chosen as a method
for rapid visual screening during field survey to collect data
for statistical analysis. In this case study, seismic vulnerability
assessment of buildings is carried out for the city Cox’s Bazar,
situated on the bank of the Bay of Bengal, the main tourist’s
city of Bangladesh. The assessment showed seismic
vulnerability factors recognized with heavy overhanging
(26%), absent of basement (25%), pounding possibility (14%),
plan irregularities (12%) and soft storey (7%).It is also
observed that if one of the soft storey buildings under
liquefaction fail which will affect the others very easily
because all the building structure are very close to each other.