1.IntroductionThis study investigates the plastic methods ofanalysis in steel structures. Four structures wereanalysed in different behaviour conditions. Forthe realistic behaviour of structures, analysis wascarried out by Sap2000 FEM software. Theresults obtained are compared and discussed,concluding in what an engineer must take intoserious consideration as far as plastic design isconcerned.

• Elastic Perfect Plastic (EPP)

• Realistic Elastic Plastic including the strainhardening (REP)

• Realistic Elastic Plastic including both strainhardening and second – order effects (REPS)

2.Literature ReviewStress – strain behaviour of a cross section.

Elastic Perfect Plastic behaviour for designpurposes.

• It has been proved by experiments that whenstrain hardening effect takes place, it inducesconsiderable extra strength to a structure.

• Second – order effects have been proved tooutshine the advantages of plastic design,resulting in a more sensitive structure than theone that the simple plastic theory predicts.

•

4.Conclusions•Manual methods of analysis and Sap2000 results coincide with great accuracy.

• Strain hardening effect is proved to be beneficial.

• Second – order effects reduced considerably the durability of the structure, resulting in a lower collapse load than the one that simple plastic methods of analysis suggest.

• Second Loading configuration proved critical.

• Further study is needed to define clearly the impact of those effects on the structures.

3.Results and Discussion

Application 1 (EPP)According to Static Theorem: Free and reactant BM method were used formanual calculations of collapse load (Wc).

The results of manual computations and Sap2000are identical.

Application 2 (EPP)According to Kinematic Theorem: The principles of virtual work method wereused for manual computations of collapse load.

The results obtained from both analyses coincidewith great accuracy.

Conclusions

Georgios Michas

Supervisor: Dr. Alessandro PalmeriBeng (Hons) in Civil & Structural Engineering, May 2009

Application 3 (EPP & REP)According to Kinematic Theorem By the principles of virtual work

Both manual and Sap2000 analyses found thesame collapse mechanism and collapse load.

Application 4 (EPP – REP – REPS)Push over analysis were performed by Sap2000.

Two different distributions of lateral loadingaccording to EC8, in order to simulate possibleseismic forces that could act on the structure.

Plastic analysis of steel structures

STRUCTURAL ANALYSISFOR THE GANTRY LIFT SYSTEM

Maxim KarpushenkoBeng (Hons) Civil and Structural Engineering

Project Supervisor: Dr A PalmeriIntroductionFrom the earliest times people have faced the problem ‘how to lift aload’. Progress made since that time in advancing the liftingtechnology, science and engineering allows lifting and transportingobjects of huge mass. With aid of advanced software modelling ofcomplicated structural systems becomes more accurate and savesconsiderable time required to complete calculation.

Further Recommendations• The partial fixity of joints can be modelled with assistance of

SAP2000, as in practise, all joints are semi-rigid and only braces areconnected with pins, which do not transfer any moment betweencomponents.

• Take into account lateral skidding of the gantry lift system itself.• Operation of the skidding system might be modelled as series of

push/pull steps, which might induce additional oscillations comparedto the smooth movement of the load.

• Lifting crossbeams might be added to the model as they can provideadditional restrains to the main runway beams and different modesof vibration might be obtained.

• Lifting and lowering dynamic action can be modelled supersedingneed for the additional vertical action dynamic coefficient.

Results• Static linear envelope results are slightly

lower than results provided by ALE.Difference caused by implementing differentcodes of practise for design of structuralelements i.e. BS and EC-3.

• Dynamic analysis yields more accurateresults. The reason for that is analysis of allpossible positions of load applied. Nodynamic effect is noted as moving speed isvery slow. The 1.7% increase in bendingmoment, compared to the static analysisenvelope.

Aims and Objectives• Apply standard procedures for structural analysis and design

according to the Eurocodes.• Compare design of the gantry with British Standards.• Consider sensitivity of the results to the speed of moving load and

structures nonlinearity properties with aid of SAP2000 software.• Assume possible improvements of the analysis model in order to

gain more accurate results.

Assumptions• All joints are assumed to be pinned and stability of the structure

provided by the means of the bracing system (i.e. non-swaystructure).

• Elastic-perfectly plastic material behaviour is assumed for analysispurposes.

• The three different positions for the load (initial position, mid-spanof the beam and final position) are assumed for the static analysis.

• The time-history functions are applied to represent movement ofthe load on top of the main runway beams. All possible positions ofthe load are covered.

• The speed is significantly increased to cause dynamic effect andcheck structures sensitivity and behaviour.

• Nonlinear analysis is developed to take into account deformedshape of structure, tension-only elements and other materialnonlinearities.

Analyses Types• Static Linear Analysis• Modal Analysis• Dynamic Linear Analysis for

the moving load• Dynamic Linear Analysis for

the load moving at high speed• Static Nonlinear Analysis• Dynamic Nonlinear Analysis• Sinking Support Conditions• Robustness Analysis

Component Stresses ALE ResultsStatic

AnalysisDynamic

(Slow)Dynamic

(Fast)

Beam at mid-span (f4)

Major Moment 3-3

11804.1kNm 11385.7 kNm 11583.7 kNm 11725.4 kNm

Minor Moment 2-2

452.8 kNm 456.7 kNm 565.7 kNm 573.6 kNm

Abs. Deflection UZ (j6)

51.3 mm 50.6 mm 50.5 mm 50.8 mm

Beam at support (f2)

Shear Force 2632.3 kN 2537.6 kN 2319.4 kN 2189.9 kN

Column (Reaction)

Axial Force (j13) 2932.3 kN 2913.6 kN 2026.7 kN 2059.73 kN

• Moving load at high speed increases dynamic effect and causes additionaloscillations, which result in higher values of critical stresses. Further increase inbending moment by 141.7kNm is achieved.

• Stresses obtained from Nonlinear analysis are the same, the only differencefound is joints displacement results.

• Sinking support analysis does not cause significant stress increase.• Robustness analysis shows what all structural members are important and

failure any of them causes the total collapse of the Gantry structure.

Figure 1: Gantry in Operation

Figure 2: 3D SolidWorks Model

Figure 3: SAP2000 Model. Frames.

Figure 4: Static Analysis Moment Envelope

Figure 5: Moment Diagram at mid-span: Slow Load Figure 6: Moment Diagram at mid-span: Fast Load

Table: Critical Stresses Comparison

MANAGEMENT OF BRIDGESGEORGIA LEONTI supervisor: Dr Palmeri

OBJECTIVES

Bridges attain their designlife, remain open to trafficcontinuously and their riskof failure is always very low.These objectives are to beachieved sustainably and atminimum lifetime cost.

This project separates bridgemanagement into project andnetwork level management.Project- level aspects, such as theload carrying, condition-performance and non- destructivetests.Network-level is more associatedwith the rate of deterioration,optimal maintenance and theeffectiveness of varietymaintenance strategies, predictionof future condition andserviceability of the stock.

‘Bridge management’ encompasses abroad variety of activities aimed atensuring the safety and functionality ofbridges. An efficient bridge managementscheme is necessary to support thehighway remaining continuously open tothe traffic with a sufficiently low level ofrisk.The results from activities such as:

Inspection,Assessment of load- carrying capacitySampling –non destructive tests are used

to prioritise the maintenancerequirements

The evaluation of their existingcondition

Their rate of deterioration.are necessary to decide the most suitable

time to carry out maintenance work.

INTRODUCTIONThis project reviews bridge management requirements.It presents recommendations for:the optimisation of inspectionmaintenance of bridgesthe prediction of deteriorationservice lifeand management strategyMany aspects of bridge management relate to themanagement of a stock of bridges.Techniques which are used to aid the managementof bridge stocks include:whole- life cost,sustainabilityand risk analysisThese techniques make use of economic or probabilistic models.

MAIN BODY

Project level bridge management:

There are several ways to evaluate bridge condition.The main phases of deterioration.

Progressive breakdown of protective systemsPhysical deterioration of bridge elements, leading to a

reduction lifeSignificant damage with possible hazards to usersSubstantial damage

Preventative maintenance techniques should beeffective and easy to carry out.Assessment of load carrying capacity of a bridge ismade when deteriorationis considered to be sufficiently as to have reduced thestrength or when loadingstandard is changedSampling and non destructives tests used for specialinspection

Network level bridge management:The development of relational database systems hasenabled bridges to be managed as stock. This hasnumber of potential advantages.

Design features and materials with defects can beidentified

The influence of bridge maintenance on traffic flowRate of deterioration of a particular bridge can make

use of information of bridges of similar stock and agein the stock

The cost effectiveness of different maintenancemethods can be established

Maintenance work on different bridges in the stockcan be prioritised

Maintenance programmes and budgets for the stockcan be planned.

The performance of a maintenance programme can beevaluated in terms of change in the overall condition ofthe bridge stock.

CASE STUDYSpecifically, in this project, we expose the results and research instructural risk analysis applied to computerized managementsystem, through case-study of true project: the Rion-AntirionBridge, risk-based surveillance and maintenance.In order to entire the health monitoring system and to supply thebridge owner, a generallyreliable surveillancemaintenance strategythe inspectionand maintenance manual has been districted according to theresults of the risk analysis. The strategy for parameter adjustmentis as well defined in the manual.Inspection frequencies and intervention thresholds are doggedfor the whole life of the arrangement.The inspection and maintenance strategy has been computerizedin the inspection and maintenance management software. Thesoftware includes a defect management system; rely on drawingmanagement, as well as inspection checklists associated to amodified rating system.The inspection checklists allow, by simple requests on thedatabase, to focus on the elements with harmful problems thanksto the rating system.The drawing defect management allows to:

Do full structural analysesQuantify the maintenance and repair costs according to the

amount of defects of the similar type that are present on the bridgeGuess in parallel and during the years, the evolution rate of every

type of defect, and consequently decide the best time and locationsto perform maintenance in order to get the maximal efficiency.

CONCLUSIONSMany research works are being carried out worldwide on inspectionand health monitoring, capacity assessment, life-cycle cost analysisand maintenance and repair. Efforts should be addressed in thefollowing directions:Development of simplified methods based on the findings ofadvanced research but made more useful to the managing engineer.Need of codification and standardization in some specific areas asthe condition assessment and make use of new-fangled equipmentand techniques for bridge repair and strengthening.Whole-life cycle cost and initial cost increase as the service lifeincreases. It is more reasonable to use annual cost.A proposed database system is introduced in this project in orderto facilitate in-house works and to make networked linkagesnationwide. Further study is planned to introduce this proposedmodel in actual practice of bridge maintenance and management.

REFERENCES1. Frangopol D.M., Kong J.S. & Gharaibeh E.S. 2001. Reliability-Based Life-Cycle Management of

Highway Bridges. Journal of Computing in Civil Engineering, ASCE, Vol 15, January 2001, p 27 – 34

2. Frangopol, D. M. & Lin, K. Y. 1997. Life-Cycle Cost Design of Deteriorating Structures. Journal of Structure Engineering, ASCE. Vol. 123, No. 10, pp. 1390-1401.

3. Frangopol, D.M.. "Use of monitoring extreme data for the performance prediction of structures: General approach", Engineering Structures, 200812

INTERNAL SOURCEShttp://www.asecap.com/english/documents/SESSION1AGEFYRAEN.pdf, 1/4/209http://www.atyponlink.com/TELF/doi/abs/10.1680/cien.144.1.166.39555, 1/4/209http://www.cosis.net/abstracts/EGU06/03272/EGU06-J-03272.pdf, 2/4/2009http://www.fabermaunsell.com/MarketsAndServices/36/74/index.jsp, 3/4/2009http://www.gefyra.gr/en/index.php?ID=2ybqTBbWXdUn4xZd, 4/4/2009

=>Computer –based databases and their associated analysisalgorithms are called BMS. They consist of a number ofmodules such as:

inventoryinspection, assessment and test recordsmaintenance recordseconomics of maintenance methodseconomics of traffic disruption and managementrate of deteriorationoptimised and prioritised programmes

Other techniques used in the management of bridges:whole –life costingrisk analysissustainability assessment