MMI Engineering Inc.

Houston, TX, United States

MMI Engineering Inc.

Houston, TX, United States
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Sancio R.,MMI Engineering Inc.
Proceedings of the Annual Offshore Technology Conference | Year: 2016

Although numerous studies have been conducted, a recommended practice for incorporation of earthquake loading into the geotechnical design considerations for subsea structures such as wells, manifolds, and PLETs, and pipelines is not consistent. Industry guidance provided in ISO 19901-2 and the more recent API adoption, RP2EQ, provide performance-based recommendations for selection of a two-level seismic design. At the first level the structure is designed to retain its full capacity (and likely its operability) at ground motions with a return period typically under 200 years that depends on the exposure level of the structure. At the second level ground motions that are less likely to occur over the lifetime of the structure are used to ensure global failure is avoided. The guidance, however, was written specifically for fixed steel structures and fixed concrete structures for which exposure incorporates first and foremost life safety, with secondary consideration for environmental exposures caused by system failures, and economic losses to the owners and operator. Subsea field architectures that only include subsea gathering and distribution systems and structures present no exposure to human life, therefore the decision to incorporate earthquake loads should be done with consideration given to mitigation and prevention of environmental releases and tolerable levels of damage. The latter include consideration of: (i) costs associated with production down time and schedule; and (ii) costs for replacement and rehabilitation of damaged facilities. In this paper we provide: (1) a discussion on existing industry guidance for reliability-based design; (2) reliability-based process for incorporating triggering of seismically-induced soil liquefaction and its consequences into foundation design, and design criteria in a moderately seismic environment with a seabed architecture that only includes manifolds, PLETs, pipelines, umbilicals, and associated structures; and (3) a reliability-based process for evaluation of seismically-induced stability of slopes and its incorporation in the evaluation of pipeline routes. Copyright 2016, Offshore Technology Conference.

News Article | November 29, 2016

MMI Engineering Ltd (MMI) is pleased to announce the appointment of Dr. John Evans as its new Managing Director.  Since 2010, Dr. Evans has successfully managed MM Engineering's Aberdeen office while fulfilling the role of technical safety lead - an area in which he has more than 25 years of professional experience. In 2015, Dr. Evans was promoted to UK Operations Manager.  His combined role saw him retain management of the multi-disciplinary teams in the Aberdeen office, however, his responsibilities were increased to cover the whole of MMI's operations in the UK.  Upon Dr. Evans' promotion to Managing Director, Dr. Simon Thurlbeck, MMI's former Managing Director and founder of their UK operations, stated, "I believe John is the right person to lead MMI through the next stage of the Company's evolution.  Since he joined us, he has demonstrated his ability to not only deliver first class solutions to his clients, but to influence and inspire those around him.  He is the perfect leader for our firm, which is founded at all levels on outstanding technical competence and outstanding client service."  MMI currently has offices in the UK, US, Malaysia and Australia.  Founded in 2001, the company provides technical consulting services to a wide range of clients across a host of industry sectors, including oil and gas, water, nuclear, security, and defence, specialising in the identification, assessment and management of man-made and natural hazards by the application of a blend of expertise drawn from a range of scientific and engineering backgrounds. Dr. Thurlbeck will be concentrating his efforts on his professional practice (Major Hazards Risk Management) as well as providing mentoring and business development support across all MMI's offices.  He recently helped found The Hydrocarbon Passive Fire Protection Network (PFPNet), an industry group aimed at improving knowledge and awareness of, and developing best practices for, passive fire protection, and he will be placing this at the core of his consulting activities. Upon accepting his new role, Dr. Evans stated, "I am honoured to assume the role as Managing Director of MMI.  Simon has led the company from strength-to-strength, growing our capabilities and establishing our presence in several key industries and global locations.  It's thanks to him and our employees, many of whom have reputations as thought leaders in their respective sectors, that so many of our clients trust us to solve their more difficult problems.  In the current business climate, it is my intention to build upon MMI's core areas of Fluid Systems and Heat Transfer, Asset Management, Safety, Structural Integrity, and Fire Protection.  Our company has a history of providing innovative solutions to some of our clients' more challenging needs, and I will be advocating this as we continue to ensure that MMI is recognised as one of the world's leading, independent, consulting companies." For more information about MMI Engineering, please visit: MMI Engineering is a technical consulting firm providing services to a wide range of industries including Oil & Gas, Nuclear, Renewable Energy, Petrochemical, Defence & Security and Aerospace.  With offices spanning all the major time zones we provide clients around the globe with technical expertise delivered with a continuous commitment to meet and exceed our client's requirements.

Dong S.B.,University of California at Los Angeles | Alpdogan C.,MMI Engineering Inc. | Taciroglu E.,University of California at Los Angeles
International Journal of Solids and Structures | Year: 2010

Many shear correction factors have appeared since the inception of Timoshenko beam theory in 1921. While rational bases for them have been offered, there continues to be some reluctance to their full acceptance because the explanations are not totally convincing and their efficacies have not been comprehensively evaluated over a range of application. Herein, three-dimensional static and dynamic information and results for a beam of general (both symmetric and non-symmetric) cross-section are brought to bear on these issues. Only homogeneous, isotropic beams are considered. Semi-analytical finite element (SAFE) computer codes provide static and dynamic response data for our purposes. Greater clarification of issues relating to the bases for shear correction factors can be seen. Also, comparisons of numerical results with Timoshenko beam data will show the effectiveness of these factors beyond the range of application of elementary (Bernoulli-Euler) theory. An issue concerning principal shear axes arose in the definition of shear correction factors for non-symmetric cross-sections. In this method, expressions for the shear energies of two transverse forces applied on the cross-section by beam and three-dimensional elasticity theories are equated to determine the shear correction factors. This led to the necessity for principal shear axes. We will argue against this concept and show that when two forces are applied simultaneously to a cross-section, it leads to an inconsistency. Only one force should be used at a time, and two sets of calculations are needed to establish the shear correction factors for a non-symmetrical cross-section. © 2010 Elsevier Ltd. All rights reserved.

Alpdogan C.,MMI Engineering Inc. | Dong S.B.,University of California at Los Angeles | Taciroglu E.,University of California at Los Angeles
International Journal of Solids and Structures | Year: 2010

We present a rigorous verification study and an extension to an existing semi-analytical finite element formulation for analysis of end and transition effects in prismatic cylinders. End and transition effects in stressed cylinders are phenomena associated with the difference between results that are predicted by the Saint-Venant solutions and the actual point-wise conditions. These differences manifest themselves as self-equilibrated stress states. Notwithstanding certain well-known exceptions (e.g., restrained torsion of open thin-walled sections), such effects in isotropic cylinders are usually confined to a very small neighborhood of a terminal boundary or transition zone, and are typically neglected. For anisotropy, as in the case of most smart/active and composite material systems, they can persist much further into the interior of the structure, and need to be quantified to design geometry transition zones and to fully understand the delamination effects. In the semi-analytical approach, we first discretize the governing equations within the cross-sectional plane of the cylinder. The end-solution fields satisfy the homogeneous form of the resulting semi-analytical system of ordinary differential equations. This leads to an algebraic eigenvalue problem, and an eigenfunction expansion of the stress and displacement fields due to end effects. Unique to the present study, we formulate a procedure to quantify the transitional effects for end-to-end connected cylinders for which the displacement and stress continuity along the transition interface need to be enforced. The semi-analytical approach has several distinct advantages: (i) It is computationally efficient, as only the cross-sectional geometry is discretized; (ii) it can be applied to arbitrary cross-sectional geometries and the most general form of anisotropy; and (iii) it yields direct measures for the decay lengths (or decay rates) of any end-or transition-solution field. Analytical solutions to end-effect problems are scarce. Those that exist are for simple geometry and material constitution. We use these analytical solutions, as well as solutions obtained using three-dimensional finite element models, to verify our approach and to assess its efficiency. © 2009 Elsevier Ltd. All rights reserved.

Graf W.P.,ImageCat Inc. | Seligson H.A.,MMI Engineering Inc.
Earthquake Spectra | Year: 2011

The M7.8 San Andreas earthquake scenario for the ShakeOut exercise subjects more than a million wood-framed buildings to loads beyond their elastic capacity. Residential construction from the boom from the 1960's to 1980's relied heavily upon drywall sheathing and stucco for shear walls - more vulnerable than plywood or the gypsum lath and plaster of older buildings. During this same construction boom, many apartment buildings were built with tuck-under parking, and heavy masonry chimneys were prevalent. Based on HAZUS®MH modeling we describe, more than 30,000 (mostly older) wood buildings could be red-tagged or yellow-tagged in the scenario event. More recent wood-frames, engineered using plywood shear walls, should perform well, evenunder the conditions produced by the San Andreas event considered. Cost-effective retrofit measures exist for some of the weaknesses found in older wood construction, but seismic upgrade of wood-framed buildings with structural wood panels remains expensive and intrusive. © 2011, Earthquake Engineering Research Institute.

Choe D.-E.,MMI Engineering Inc. | Gardoni P.,Texas A&M University | Rosowsky D.,Rensselaer Polytechnic Institute
Journal of Engineering Mechanics | Year: 2010

The increased deformation and shear fragilities of corroding RC bridge columns subject to seismic excitations are modeled as functions of time using fragility increment functions. These functions can be applied to various environmental and material conditions by means of controlling parameters that correspond to the specific condition. For each mode of failure, the fragility of a deteriorated column at any given time is obtained by simply multiplying the initial fragility of the pristine/nondeteriorated column by the corresponding function developed in this paper. The developed increment functions account for the effects of the time-dependent uncertainties that are present in the corrosion model as well as in the structural capacity models. The proposed formulation is a useful tool for engineering practice because the fragility of deteriorated columns is obtained without any extra reliability analysis once the fragility of the pristine column is known. The fragility increment functions are expressed as functions of time t and a given deformation or shear demand. Unknown parameters involved in the models are estimated using a Bayesian updating framework. A model selection is conducted during the assessment of the unknown parameters using the Akaike information criterion and the Bayesian information criterion. For the estimation of the parameters, a set of data are obtained by first-order reliability method analysis using existing probabilistic capacity models for corroding RC bridge columns. Example fragilities of a deteriorated bridge column typical of current California's practice are presented to demonstrate the developed methodology. The increment functions suggested in this paper can be used to assess the time-variant fragility for application to life cycle cost analysis and risk analysis. © 2010 ASCE.

Mullapudi T.R.S.,MMI Engineering Inc. | Ayoub A.,City University London
Magazine of Concrete Research | Year: 2013

Analytical studies are conducted to develop an effective analytical model to simulate the non-linear response of reinforced concrete (RC) walls subjected to three-dimensional (3D) loads. The interaction between the concrete and steel is taken into account with consideration of the smeared behaviour of steel and tension stiffening of concrete. The proposed model is formulated to address the interaction between the axial force, shear, bending and torsion loads. The shear mechanism along the beam is modelled by adopting a Timoshenko beam approach for 3D frame elements with arbitrary cross-section geometry. The non-linear behaviour of the composite element is derived entirely from the constitutive laws of concrete and steel. The concrete constitutive model follows the softened membrane model that predicts the tensile cracking, compression crushing, strain softening, steel yielding and material damage under combined loadings. The validity of the model is established through a correlation study of experimentally tested RC shear walls subjected to monotonic loading conditions.

El-Tawil S.,University of Michigan | Ekiz E.,MMI Engineering Inc. | Goel S.,University of Michigan | Chao S.-H.,University of Texas at Arlington
Journal of Constructional Steel Research | Year: 2011

Carbon fiber-reinforced polymer (CFRP) composites have been shown to be particularly well suited for external strengthening of reinforced concrete members. However, there is limited information about how they can be used to strengthen steel structures that are susceptible to local and global instabilities. This paper discusses test results of full-scale steel flexural specimens subjected to reversed cyclic loading, some of which are wrapped with CFRP in the plastic hinge region. The main variables investigated are lateral bracing, to study the effect of CFRP wrapping on local buckling and lateral torsional buckling, wrapping scheme, and number of layers of fibers. The test results show that application of CFRP in the plastic hinge region of flexural members has substantial benefits. In particular, the CFRP wraps can increase the size of the yielded plastic hinge region, slow down the occurrence of local buckling, and delay lateral torsional buckling. These benefits reduce strain demands in the critical plastic hinge region and substantially improve energy dissipation capacity within the plastic hinge region. © 2010 Elsevier B.V. All rights reserved.

Jones T.,MMI Engineering Inc.
Institution of Chemical Engineers Symposium Series | Year: 2015

The understanding of the explosion hazards on fixed and floating offshore facilities is required to be able to demonstrate that risks are ALARP (As Low As Reasonably Practicable). It is becoming increasingly common to adopt a risk based approach whereby overpressures are calculated across a range of frequencies. Such an approach is typically referred to as an Explosion Risk Analysis (ERA). In order to understand the explosion hazards, one of the key aspects is to calculate the range of potential gas cloud sizes that can arise from an accidental release from the different inventories present. This is achieved by conducting dispersion analysis using either empirical or CFD (Computational Fluid Dynamics) methods which are not well validated. The scope of this paper is as follows; • Validate the use of CFD for calculating cloud sizes by comparing the results with experimental data. • Validate the Frozen Cloud concept. © 2015 Amec Foster Wheeler.

Ballantyne D.,MMI Engineering Inc.
Journal - American Water Works Association | Year: 2010

Pipeline damage caused by earthquake shaking and permanent ground deformation (PGD) is the most significant contributing factor to system failure in earthquakes. Pipe performance during an earthquake depends on four parameters, ruggedness, resistance to bending, joint flexibility, and joint restraint. Quantification of the PGD is required for the analysis of pipelines. Liquefaction probability should be mapped and overlain on the pipeline distribution system network using a geographic information system (GIS). A pipe fragility relationship should then be applied to obtain an estimate of the pipe failure rate, and the results should be plotted to show the most vulnerable pipelines. The types of pipe material and joint types used must be understood before their expected performance can be evaluated. System monitoring and control can be an effective way to maintain some level of post-earthquake system functionality.

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