Analysis and Design Of Machine Foundation

Abstract

Contemporary developments in industry are characterized by the steady increase in power of machine. Machines, engines, generators, turbines, power generation and transmission equipment are some of the main components in any industrial activity. All these are generally heavy and generate dynamic loads and moments and have to be supported using ‘Foundations’. These machines generate lot of vibrations and there is continual trend towards more powerful and faster production machines, which has led to higher dynamic loads giving rise to more intense vibrations of floors.These vibrations, if not controlled by proper balancing of the machines, can cause failure of the machines, structures and foundations due to fatigue, wear and tear of machine parts such as bearing, shafts, gears, and the noise can gradually become excessive and unbearable. Also, if the frequency of the dynamic forces generated in a machine or structure is close to the natural frequency of the whole system, resonance induces excessive responses leading to failures. Machine foundations are designed such that the dynamic forces of machine are transmitted to the soil through the foundation so that all kinds of harmful effects are eliminated. The aim of present work is to review the Analysis and Design of existing machine foundation structures (Block Foundation and Frame Foundation) built on site. Analysis of Block Foundation has been carried out manually by preparing EXCEL spread sheets.Design of the same has been done by manual calculations. Analysis of Frame foundation has been is also carried out using software (STAAD Pro 2006) and Design is carried out through manual calculations.Analysis of block foundation having pump is also done by preparing EXCEL spread sheets and design of the same has been done manually. Parametric study of both the foundation for the different soil properties is carried out for existing foundations . Analysis and design of Block Foundation includes study of geotechnical data, vendor provided data (machine speed, weights of the machines, foundation loads and relevent drawings), code and standards [IS 2974 (part1) 1982 – for IV analysis and design, IS 5249 : 1992 – for dynamic properties of soil] and specifications of Bechtel France S.A.S. It also includes static and dynamic analysis of framed foundation using STAAD Pro2006 and Design of the same is carried out by manual calculation,includes static and dynamic analysis,model is prepared using ‘Finite Elements’like 4- noded plate element.Plate stresses are found out from analysis and based on those stresses design is carried out. Dynamic analysis is carried out using ‘Time History analysis’. Resonance check is carried out from free vibration analysis and from forced vibration analysis ,Time-displacement ,Time-velocity checks are carried out.Design is carreid out as per IS 2974 (part 3) :1992 One more case study is carried out,which is block foundation,but having horizontal pump.It also includes analysis and design of pump foundation. Analysis is carreid out preparing excel sheets .while,Design is carried out by manual calculation. Analysis includes eccentricity check, resonance check, amplitude check,bearing capacity check,limiting velocity check.Design is carried out as per IS 2974(PART –I):1982 .Parametric study for different soil properties for zone 4 and zone 5 is carried out for both the foundation(Block foundation and framed foundation) . The content of major project is divided into various chapters.Chapter 1 is of general nature and it serves to introduce the topic.Chapter 2 gives literature survey carried out during the work. Chapter 3 presents analysis of block foundation .It includes theoritical aspects of various methods and discussion of selecting elastic half space approach.It also includes excel sheets prepared for analysis of block foundation and design checklist. Chapter 4 represents design of block foundation as per ACI 318 ,with detailed drawings.Chapter 5 presents introduction of finite element using STAAD Pro.,introduction of plate elements,application of loads on plate elements,sign convention of stresses and moments,capabilities of STAAD Pro.,intoduction of dynamic analysis in STAAD Pro.Chapter 6 presents static analysis and design of framed foundation.It includes introduction of frame foundation,vendor drawing and data,design parameters,preliminary sizing of machine foundation,modelling,load calculation and design of operating slab,columns,and mat slab as per Indian Standards.Chapter 7 presents dynamic analysis of framed foundation.It includes introduction and free and forced vibration analysis of framed foundation using STAAD Pro.,dynamic results with various checks. Chapter 8 represents analysis and design of block foudation having horizontal pump.Analysis is carreid out by preparing excel work sheets .while,Design is carried out by manual calculation.Analysis includes eccentricity check,resonance check,amplitude check,bearing capacity check,limiting velocity check. Design is carried out as per IS 2974(PART –I):1982 .Chapter 9 includes parametric study of both (Block and framed) foundation for different properties of soil. Chapter 10 includes summary, conclusions and future scope of work.