ECEM
Unit 1Elements of civil engineering and mechanicsQ1)Convergence in CFD.A1) Convergence in CFDCreating a sculpture requires a highly talented artist with the ability to imagine the final product from the beginning. Yet a sculpture can be a simple piece of rock in the beginning but might become an exceptional artwork in the end. Completely gradual processing throughout carving is an important issue to obtain the desired unique shape. Keep in mind that in every single process, some of the elements, such as stone particles, leftovers, are thrown away from the object. CFD also has a similar structure that relies on gradual processing during the analysis. In regions that are highly critical to the simulation results (for example a spoiler on a Formula 1 car) the mesh is refined into smaller elements to make the simulation more accurate. Convergence is a major issue for computational analysis. The movement of fluid has a non-linear mathematical model with various complex models such as turbulence, phase change, and mass transfer and convergence is heavily influenced by them. Apart from the analytical solution, the numerical solution goes through an iterative scheme where results are obtained by the reduction of errors among previous stages. The differences between the last two values specify the error. When the absolute error is descending, the reliability of the result increases, which means that the result converges towards a stable solution.How do analysts decide when the solution is converged? Convergence should go on and on until a steady-state condition has been obtained, even if the aimed case is transient, which indicates results changing through time. Convergence has to be realized for each time-step as if they all are a steady-state process. What are the criteria for convergence? The residuals of equations, like stone leftovers, change over each iteration. As iterations get down to a threshold value, convergence is achieved. For a transient case, those processes have to be achieved for each of the time steps. Furthermore, convergence might be diversified as follows:Can be accelerated by parameters as initial conditions, under-relaxation, and Courant number. Doesn’t always have to be correct, yet the solution can converge; preferred mathematical model and mesh would be incorrect or have ambiguities. Can be stabilized within several methods like reasonable mesh quality, mesh refinement, using discretization schemes first- to second-order. Ensure that the solution is repeatable if necessary as to refrain ambiguity. Q2) Write Applications of CFD ?A2) Where there is fluid, there is CFD. Having mentioned before, the initial stage to conduct a CFD simulation is specifying an appropriate mathematical model of reality. Rapprochements and assumptions give direction through solution processes to examine the case in the computational domain. For instance, fluid flow over a sphere/cylinder is a repetitive issue that has been taught by the lecturer as an example in fluids courses. The same phenomenon is virtually available in the movement of clouds in the atmosphere which is indeed tremendous.Q3) Explain incompressible, compressible, laminar, turbulent flow?A3) Incompressible and Compressible flowIf compressibility becomes a non-negligible factor, this type of analysis helps you to find solutions in a very robust and accurate way. One example would be a Large Eddy Simulation of flow around a cylinder.Laminar and Turbulent flowDifferent turbulence models play a role in this type of analysis. A lot of computing power is required to solve turbulence simulations and its complex numerical models. The difficulty of turbulence is the simulation of changes over time. The entire domain where the simulation takes place needs to be recalculated after every time step.The valve is one possible application of a turbulent flow analysis.Mass and Thermal transportMass transport simulations include smoke propagation, passive scalar transport or gas distributions. To solve these kinds of simulations, OpenFOAM solvers are used.Heat exchanger simulations are one possible application. Q4)Different Types of CFD Applications A4) Computational Fluid Dynamics tools diversify in accordance with mathematical models, numerical methods, computational equipment, and post-processing facilities. As a physical phenomenon could be modelled with completely different mathematical approaches, it would also be integrated with unlike numerical methods simultaneously. Thus, a conscious rapprochement is an essential factor on the path to developing CFD tools. There are several licensed commercial software solutions, along with open source software. One of the most used open-source solvers for CFD is OpenFOAM.Q5) Explain DESIGN METHODOLOGY?A5)Step 1: Case Study: In order to carry out this research a different method is used for both Geometric and Pavement Design of highway. For Geometric Design of Highway MX ROAD software is used. In Geometric Design of Highway the following procedures are taken: - First the surveying data is collected from the field through the route. For each point three reading is taken that is Northing, Easting and Elevation. Step 2: Data Collection: Topography survey for 8 km(Ch.67.73km-75.72km) at an interval of 10m along the alignment (Longitudinally) and 5m interval up to 20 m across the road on either side (Transverse) Which consist of X Y Z co-ordinates (i.e. Easting, Northing and Reduced Level) is done. Soil sample for every 1km and check the CBR is made. Step 3: Design Data: By considering all the IRC specification and existing features of project corridor the following design values are taken for executing the design of the project work by using MXROAD softwareChainage:-67.73KM to 75.72KM, Length 7.990KM, Design Speed - 100 kmph and 30 kmph, Land width or right of way – 30m, Setback – 2 to 5 m., Roadway Width – 15.0 m, Carriageway Width – 7.5 m, Shoulder width – 2.5 m, Cross Slope or Camber– 2.5%, Earthen surface – 3.0%, Embankment slope –1 V : 2 H, Super Elevation – maximum 7% or 0.07, Radius of Horizontal Curve – Ruling Minimum 230 m, Radius at which no super elevation is required - > 1200 m, Radius at which 7% super elevation is achieved – 230 m, Extra Widening of Carriageway at Curves – 0.6 m, Gradient maximum – 3.3 %, Limiting Gradient maximum – 5%, Minimum Gradient – 0.3%, Minimum length of vertical curve – 50 m. Step 4: Standard String Naming:- The MX standard string naming convention (SNC) has been formed to give automatic integration to any design produced from any of the MXROAD option. Strings created by the MXROAD option are assigned names which store the following information, string type, associated master alignment which defines the string group, specific road features and side of master alignment on which the string was created. Step 5: Surface Analysis:- This option is used for analysing the surface on which the design has to be built.This is essential to confirmthat the imported data is correct and contains no errors. Typically the analysiswill high light errors in level and will also provide a graphical representation of the existing surface. Step 6: Alignment Design:- The alignment design option are used to create the alignment for the road design by choosing Quick alignment option, Horizontal Design, Vertical profile can be done in limited time duration.Q6) Explain Applications of Building Information Modelling.A6) A building information model can be used for the following purposes:Visualization: 3D renderings can be easily generated in house with little additional effort. Fabrication/shop drawings: It is easy to generate shop drawings for various building systems. For example, the sheet metal ductwork shop drawings can be quickly produced once the model is complete. Code reviews: Fire departments and other officials may use these models for their review of building projects. Cost estimating: BIM software has built-in cost estimating features. Material quantities are automatically extracted and updated when any changes are made in the model. Construction sequencing: A building information model can be effectively used to coordinate material ordering, fabrication, and delivery schedules for all building components. Conflict, interference, and collision detection: Because building information models are created to scale in 3D space, all major systems can be instantly and automatically checked for interferences. For example, this process can verify that piping does not intersect with steel beams, ducts, or walls. Forensic analysis: A building information model can be easily adapted to graphically illustrate potential failures, leaks, evacuation plans, and so forth. Facilities management: Facilities management departments can use it for renovations, space planning, and maintenance operations. The key benefit of a building information model is its accurate geometrical representation of the parts of a building in an integrated data environment. Other related benefits are as follows:Faster and more effective processes: Information is more easily shared and can be value-added and reused. Better design: Building proposals can be rigorously analyzed, simulations performed quickly, and performance benchmarked, enabling improved and innovative solutions. Controlled whole-life costs and environmental data: Environmental performance is more predictable, and lifecycle costs are better understood. Better production quality: Documentation output is flexible and exploits automation. Automated assembly: Digital product data can be exploited in downstream processes and used for manufacturing and assembly of structural systems. Better customer service: Proposals are better understood through accurate visualization. Lifecycle data: Requirements, design, construction, and operational information can be used in facilities management. After gathering data on 32 major projects, Stanford University’s Center for Integrated Facilities Engineering reported the following benefits of BIM.Up to 40% elimination of unbudgeted change, Cost estimation accuracy within 3% as compared to traditional estimates, Up to 80% reduction in time taken to generate a cost estimate, A savings of up to 10% of the contract value through clash detections, andUp to 7% reduction in project time. Q7) Explain STAAD Pro?A7) This is a structural design and analysis tool developed by Research Engineers which was later acquired by Bentley Systems, a CAD/CAM software company based in Pennsylvania. STAAD Pro is considered as the best structural analysis software and adopted by over a million structural engineers around the globe. It features ease of use and an array of essential tools required for accomplishing an analytical process on different structures.STAAD Pro further integrates with a number of other Bentley products. The models created using STAAD Pro can be imported to OpenSTAAD so as to make the models transferrable to other third-party tools.Q8) What is SAFE software?A8) This software is mostly used in designing foundation slab systems and concrete floors. SAFE is a comprehensive package that combines all the aspects of engineering design process – from creating layout to detail drawing production in a single, intuitive environment. It enables highly advanced local assessment of foundation systems within larger structures and imports files from CAD, ETABS, and SAP2000. Some of the other benefits it offers are:Wide-ranging templates to quickly initiate a model Post-tensioning Support conditions and loadings Q9) Explain NASTRAN?A9) Interfacing with the MSC Nastran and NX Nastran general purpose finite element programs is based on the formatted Bulk Data File for FEM geometry and element properties and binary OUTPUT2 files created with the PARAM, POST, -5 command are used to interface element matrices and shapes (static, modal normal or complex). Punch files are used to import FRF data but can also be used to import modes. Bulk Data can be read or written; OUTPUT2 and punch files are read-only.
The Nastran interface and driver program can also be used with NE/Nastran.Q10) Explain SAP2000.A10) The SAP2000 interface program has 2 operating modes: (i ) reads FE model definition and mode shapes from SAP2000 s2k input files, and (ii) using the SAP2000 OAPI library to communicate with SAP2000. With the OAPI interface, bidirectional communication is supported and allows for piloting SAP2000 from FEM tools to perform FE analysis, pre-test analysis, correlation analysis, sensitivity analysis and model updating. Q11) Define physical inspection of damaged structure? A11)Some of the use full information may be obtained from the physical inspection of damaged structure, like nature of distress, type of distress, extent damage and its classification etc, their causes preparing and documenting the damages, collecting the samples for laboratory testing and analysis, planning for in situ testing, special environmental effects which have not been considered at the design stage and information on the loads acting on the existing structure at the time of damage may be, obtained. To stop further damages, preventive measure necessary may be planned which may warrant urgent execution. Q12) How deterioration occurs due to corrosion?A12)Spelling of concrete cover Cracks parallel to the reinforcement Spelling at edges Swelling of concrete Dislocation Internal cracking and reduction in area of steel reinforcement Q13) What are the steps in selecting a repair procedure?A13)Consider total cost Do repair job in time If defects are few & isolated repair on an individual basis Otherwise do in generalized manner. Ensure the repair prevents further development of defects In case of lost strength, repairs should restore the strength If appearance is a problem, the number of applicable types of repairs become limited the repairs must be covered Repair works should not interface with facilities of the structure Take care in addition of section to a member and in reattributing live loads and other live load moments. After selecting a suitable method of repairs, and after considering all the ramifications of its application, the last step is to prepare plans & specification and proceed with the work. Q14) Discuss about the design and construction errors leading to deterioration of a structure? A14) Design of concrete structures governs the performance of concrete structures. Well designed and detailed concrete structure will show less deterioration in comparison with poorly designed and detailed concrete, in the similar condition. The beam-column joints are particularly prone to defective concrete, if detailing and placing of reinforcement is not done properly. Inadequate concrete cover may lead to carbonation depth reaching up to the reinforcement, thus, increasing the risk of corrosion of the reinforcement. Q15) What are the techniques required for repairing cracks?A15)Bonding with epoxies Routing and sealing Stitching Blanketing External stressing Grouting Autogenously healing Q16) Difference between defects, distress and deterioration Defects ?A16) The defects are the flaws those creeps into structure because of design mistakes or poor workmanship during manufacturing, fabrication and construction, before it begins its service life, or by inappropriate operation and maintenance during its service life. The flaw that has a potential to lead to a failure, becomes a defect.Distress: It is a collective term for the physical manifestation of problems such as cracks, spalls, pop-outs, staining, decay or corrosion. Distress can be thought of as the symptoms indicating that the defects are present. Deterioration: It is the gradual loss of the desired material properties due to different degradation factors. Deterioration unlike defects, may not surface at the beginning of the service life of a structure, but is rather time-dependent. However, some forms of deterioration may develop early in the service life of structure and others manifest later.
The Nastran interface and driver program can also be used with NE/Nastran.Q10) Explain SAP2000.A10) The SAP2000 interface program has 2 operating modes: (i ) reads FE model definition and mode shapes from SAP2000 s2k input files, and (ii) using the SAP2000 OAPI library to communicate with SAP2000. With the OAPI interface, bidirectional communication is supported and allows for piloting SAP2000 from FEM tools to perform FE analysis, pre-test analysis, correlation analysis, sensitivity analysis and model updating. Q11) Define physical inspection of damaged structure? A11)Some of the use full information may be obtained from the physical inspection of damaged structure, like nature of distress, type of distress, extent damage and its classification etc, their causes preparing and documenting the damages, collecting the samples for laboratory testing and analysis, planning for in situ testing, special environmental effects which have not been considered at the design stage and information on the loads acting on the existing structure at the time of damage may be, obtained. To stop further damages, preventive measure necessary may be planned which may warrant urgent execution. Q12) How deterioration occurs due to corrosion?A12)
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