1. PROJECT DATA

Program: PNCDI II – Research projects for stimulating the formation of young independent research teams (TE)

Project Code: TE-38

Project duration: Sept. 2010 – July 2013

Summary: Steel structures subjected to compression and bending moment require a thorough investigation using advanced numerical methods that take into account all the specific cases of loading, restraining modes and geometric and material imperfections. These, in fact, are much more complex than the cases covered by the normative currently in effect. The final version of the European norm EN1090-2 provides admissible limits for steel elements manufacture and assembly equal to a deviation from linearityof1/750*L. Initial bow imperfections of the elements, supplemented with residual stresses considered for the development of European buckling curves, have value 1/1000*L. In the conditions in which the value of the allowed tolerances is higher than the afore mentioned imperfections, further investigations are necessary to verify if the actual value of the partial safety factor (γ_M0=1.00) is still adequate. The main objectives of the project are the sensitivity analysis of steel structures with tapered elements, to different types of manufacturing and assembling imperfections. Studies performed and presented in several scientific papers have demonstrated the importance of considering in the calculation the various initial imperfections such as deviation from verticality of the columns(in plane or out-of-plane), initial bow imperfections, sectional imperfections, and so on. However, the question arises: What is the most important form of imperfection or its value? The research project aims to find answers to the problems listed above, and to achieve these objectives will be carried out parametric studies with advanced calculation programs. Experimental tests will be performed in the laboratory CEMSIG-UPT to calibrate the computational models. The results will be compared in the final analytical results, following the calculation of the normativeSR-EN1993-1-1.

2. RESEARCH TEAM

Project manager:	SL. Dr. ing. Mircea CRISTUTIU
Members:	SL. Dr. ing. Adrian DOGARIU	researcher
	Ing. Daniel NUNES	research assistant
	Dr. ing. Sorin BORDEA	researcher

3. DEVELOPMENT OF THE RESEARCH PROJECT

3.1 Year 2010

3.1.1 Objectives/activities 2010

O1: Study of the influence of imperfections on isolated elements(beams, columns) subjected to axial force and bending moment with variable section:

A1:Documentation/Analysis by FEM/

A2: Study of the influence of imperfections with FEM in plane or out-of-plane/ Comparisons FEM-analytic results

A3:Dissemination of results/Design and partial acquisition of specimens for the experiments Phase I /Preparation of the annual research report

 

3.1.2 Achieved results 2010

3.1.3 Published papers 2010

I. Mircea Cristutiu, Dan. Dubina - Influence of member components on the structural performance of beam-to-column joints of pitched roof portal frames with class 3 and 4 sections Proc of International Conference on Steel and Composite Structures SDSS-2010, Rio de Janeiro, Brazilia, sept.2010, p 191

Zs. Nagy, I. Mircea Cristutiu - Advanced nonlinear investigations of a 50 m span frame case study: the steel structure of the ice rink, city of Targus-Mures, Romania Proc of International Conference on Steel and Composite Structures SDSS-2010, Rio de Janeiro, Brazilia, sept.2010, p 649.

Zs. Nagy, I. Mircea Cristutiu – Initial imperfection influences on the structural behavior of steel portal frames with variable cross sections and some susteinability considerations – case study. Proc of 6th WSEAS International Conference on Energy, environment, ecosystems and sustainable development (eeesd '10) 3rd Wseas international conference on landscape architecture (la '10)”, Timisoara, Romania, oct. 2010, p21

I. Mircea Cristutiu, D. Grecea – Influence of connected member’s component son the structural performance of bolted beam-to-column joints of pitched roof portal frames. Proc. of the International workshop „Global and Regional Environmental Protection” B.E.N.A - Glorep 2010, Timisoara, Romania, nov.2010, p. 196

N. Muntean, I. Mircea Cristutiu – Erection and manufacturing imperfection influence on steel frame behaviour. Proc. of the International workshop „Global and Regional Environmental Protection” B.E.N.A - Glorep 2010, Timisoara, Romania, nov.2010, p. 228

Zs. Nagy, I. Mircea Cristutiu – Sustainability aspects of an ice-rink-City of Tg. Mures-Romania-Case Study Proc. of the International workshop „Global and Regional Environmental Protection” B.E.N.A - Glorep 2010, Timisoara, Romania, nov.2010, p. 253

I. Mircea Cristutiu – Stabilitatea cadrelor cu elemente variabile: Influenta imperfecțiunilor si a legaturilor laterale. Vol. - A-12-a Conferința Naționala de Construcții Metalice – Realizări si preocupări actuale in ingineria construcțiilor metalice, nov. 2010, Timișoara, Romania, p.97

3.1.4 Conference attendance 2010

05.09.2010 - 15.09.2010 – SDSS’2010 – International Conference on Stability and Ductility of Steel Structures, Rio de Janeiro, Brazil;

21.11.2010-23.11.2010 - Conference “ 6th WSEAS International Conference on ENERGY, ENVIRONMENT, ECOSYSTEMS and SUSTAINABLE DEVELOPMENT (EEESD '10)

3rd WSEAS International Conference on LANDSCAPE ARCHITECTURE (LA '10)”, Timisoara, Romania

26.11.2010-28.11.2010 - Conference “ Global and Regional Environmental Protection – GLOREP 2010” organized by: Balkan Environmental Association, Thessaloniki, Greece and “Politehnica” University of Timisoara, Timisoara, Romania

26.11.2010-27.11.2010 – Conference „A 12-a CONFERINȚĂ NAȚIONALĂ DE CONSTRUCȚII METALICE” Realizări si preocupări actuale in ingineria construcțiilor metalice, Timisoara, Romania

3.2 YEAR 2011

3.2.1 Objectives/activities 2011

O1: Study of the influence of the type of lateral restraint in the behavior of elements-columns with variable section - phase I:

A1.1. Documentation
A1.2.Experimental tests
A1.3.Analysis MEF on tested elements
A1.4.articlesinISIandBDI, and attendance in specialized international conferences in the field

O2: Study oft he influence of imperfections on single-storey steel frames, made of slender elements, under the effect of gravity loads(permanent technological, and snow):

A2.1. Documentation
A2.2. Analysis with FEM
A2.3. Study the influence of imperfections with FEM in plane and out-of-plane
A2.4. Comparisons FEM-analytic results

O3: Study of the influence of imperfections on single-storey steel frames, made of slenderelements, under the effect of horizontal loads(wind, seism).

A3.1. Documentation

A3.2. Analysis by FEM

A3.3. Study of the influence of imperfections by FEM in plane and out-of-plane

A3.4. Comparison FEM-analytic results

A3.5 Articles in ISI and BDI, and attendance in specialized international conferences in the field

A3.6. Preparing the annual research report

3.2.2 Achieved results 2011

Fig. Manufacturing and assembling imperfections taken into account in the FEM analysis

Fig. Failure modes depending on the type of lateral restraints, behavior curves

Fig. Types of lateral restraints for the experiments

Fig. Experimental layout

Fig. Behavior curves / experimental failure modes vs. FEM specimen with 8 mm web

Fig. Behavior curves / experimental failure modes vs. FEM specimen with 6 mm web

3.2.3 Published papers 2011

Cristutiu I. Mircea, Nunes Daniel L. – „Local and global stability of single storey frames made of welded plate elements with tapered web” in Acta Technica Napocensis: Civil Engineering & Architecture Vol. 54 No.1 (2011) (BDI-B+);

Cristutiu I. Mircea, Nunes Daniel L. – „Behaviour of single storey frames with tapered web members accounting for manufacturing and assembling imperfections” in Proc of „The 4th WSEAS International Conference on ENGINEERING MECHANICS, STRUCTURES, ENGINEERING GEOLOGY (EMESEG '11)” Corfu, Grecia, p219-224, (Scopus);

Cristutiu I. Mircea, Nunes Daniel L, Dogariu Adrian – “Buckling of laterally restrained steel structural elements with variable cross section considering initial imperfections” in Proc. Of -„6th European Conference on Steel and Composite Structures Budapest, Hungary”

Cristutiu I. Mircea, Nunes Daniel L. – “Influence of lateral restraints on the behaviour of thin walled welded elements with variable cross-section” in Proc. Of The 6th International Conference on Thin Walled Structures, Timisoara, Romania

Cristutiu I. Mircea, Nunes Daniel L., Dogariu Adrian – “Experimental study on laterally restrained steel columns with variable I cross sections” in Proc of The 2011 World Congress on Advances in Structural Engineering and mechanics ASEM11plus, The 2011 International Conference on Steel and Composite structures ICSCS11”, Seoul, Corea de Sud

Nunes Daniel L., Cristutiu I. Mircea – “Advanced nonlinear analysis of single storey steel frames made by elements with variable cross section” in Mathematical Modeling in Civil Engineering, Scientific Journal, Vol 7, No.4, Dec. 2011 (BDI-B+)

Cristutiu I. Mircea, Nunes Daniel L. „Influence of the initial imperfections on the seismic performance of pitched roof portal frames made of welded non-prismatic plated elements” In Proc of „ STESSA 2012 - Behaviour of Steel Structures in Seismic Areas”, Santiago de Chile, acceptata spre publicare (ISI)

Nagy Zsolt, Cristutiu I. Mircea, Nunes Daniel L. „Seismic behaviour of a large span welded steel structure considering lateral restraints and initial imperfections: a case study” In Proc of „ STESSA 2012 - Behaviour of Steel Structures in Seismic Areas”, Santiago de Chile, acceptata spre publicare (ISI).

3.2.4 Conference attendance 2011

19.05.2011-22.05.2011 – Construieste cu Steel – Cluj Napoca, Romania;

13.07.2011-17.07.2011 - „The 4th International Conference on ENGINEERING MECHANICS, STRUCTURES, ENGINEERING GEOLOGY (EMESEG '11)” Corfu, Grecia

31.08.2011- 2.09.2011-„6th European Conference on Steel and Composite Structures Budapest, Hungary”

05.09.2011-07.092011-The 6th International Conference on Thin Walled Structures, Timisoara, Romania

16.09.2011-22.09.2011 - „The 2011 World Congress on Advances in Structural Engineering and mechanics ASEM11plus, The 2011 International Conference on Steel and Composite structures ICSCS11”, Seoul, Corea de Sud

17.11.2011-18.11.2011 - The 2-nd Conference of the Young Researchers Bucuresti-Romania” Bucuresti, Romania

3.3 YEAR 2012

3.3.1 Objectives/activities 2012

O1. Study of the influence of the type of lateral restraint in the behavior of elements-columns with variable section- phase II

A1.1 Documentation
A1.2 Design of elements to be tested
A1.3 Carrying out of experimental tests
A1.4 FEM analysis of the tested and calibration of the elements of the computational model. Parametric study.
A1.5 Articles in ISI and BDI, and attendance in specialized international conferences in the field

O2. Experimental testing of single-storey steel frames provided with lateral restraints. Phase I.

A2.1 Documentation
A2.2 Design of frames to be tested
A2.3 Partial purchase of specimens to be tested
A2.4 Articles in ISI and BDI, and attendance in specialized international conferences in the field
A2.5 Preparation of the annual research report

3.3.2 Results 2012

Table. Geometry of the tested elements

 

Table. Experimental tests results

 

a) 8_NR	b) 8_LR	c) 8_TR

Figure 6. Failure modes for elements with 8 mm web

a)6_NR	b)6_LR	c)6_TR

Figure 7. Failure modes for elements with 6 mm web

Figure. Failure modes for tested elements - Centralized

Figure. Experimental layout for testing a half frame

Figure 10. Force-displacement behavior curves

g140_s160_i6	g140_s160_i8	g160_s160_i6	g160_s160_i8

Figure 11. Frames’ failure modes

3.3.3 Published papers 2012

I.M. Cristutiu & D.L. Nunes - Influence of the initial imperfections on the seismic performance of pitched roof portal frames made of welded non-prismatic plated elements. STESSA 2012 - Behaviour of Steel Structures in Seismic Areas” which will take place in the period of 9-11 January 2012 in Santiago de Chile, Chile (ISI)

Zs. Nagy, I. M. Cristutiu & D.L. Nunes - Seismic behaviour of a large span welded steel structure considering lateral restraints and initial imperfections: a case study. STESSA 2012 - Behaviour of Steel Structures in Seismic Areas” which will take place in the period of 9-11 January 2012 in Santiago de Chile, Chile (ISI)

I.M. Cristutiu & D.L. Nunes - Out of plane behaviour of pitched-roof single storey frames with tapered members considering lateral restraints, 10-th International Conference on Advances on Steel Concrete Composite and Hybrid Structures”, Singapore, Singapore (ISI)

I. M. Cristutiu, Zs. Nagy - Behaviour of a large steel pitched-roof portal frame with welded plate tapered members and king post truss rafter at the mid span. 10-th International Conference on Advances on Steel Concrete Composite and Hybrid Structures”, Singapore, Singapore (ISI)

I.M. Cristutiu, A.I. Dogariu - Behaviour of beam-column elements with variable I cross sectionsconsidering lateral restraints, CST2012 The Eleventh International Conference on Computational Structures Technology”, Dubrovnik, Croatia

I.M. Cristutiu, D.L. Nunes - Imperfection sensitivity analysis on the behaviour of single storey frames with tapered web members, CST2012 The Eleventh International Conference on Computational Structures Technology”, Dubrovnik, Croatia

I.M. Cristutiu ,D.L. Nunes, A. Dogariu - Experimental study on laterally restrained steel columns with variable I cross sections, International Journal Of Steel and Composite Structures, vol.13, no 3, Sept. 2012 (ISI)

I.M. Cristutiu & D.L. Nunes - Experimental tests for the evaluation of the structural behavior of steel tapered beam-columns with I cross section and their knee connection, 2nd International Conference on Civil Engineering and Building Materials (CEBM 2012), Hong Kong, China (ISI)

Daniel Luis Nunes, Ionel Mircea Cristutiu - Influence of lateral restraints modeling in pitched-roof single storey frames with tapered members considering initial imperfections, First International Conference for PhD students in Civil Engineering “New Researcher Generation with Challenges in Civil Engineering” CE-PhD 2012, 4-7 November 2012, (BDI)

Daniel Luis Nunes, Ionel Mircea Cristutiu - EXPERIMENTAL STUDY ON THE BEHAVIOR OF TAPERED WEB ELEMENTS UNDER COMPRESSION AND BENDING MOMENT, „The 3rd Conference of the Young Researchers”14-15 Nov. 2012, Bucharest, Romania (BDI)

3.3.4 Conference attendance2012

09.01-11.01.2012 - STESSA 2012 - Behaviour of Steel Structures in Seismic Areas” which will take place in the period of 9-11 January 2012 in Santiago de Chile, Chile

02.07-04.07.2012 - 10-th International Conference on Advances on Steel Concrete Composite and Hybrid Structures”, Singapore, Singapore

04.09-07.09.2012 - CST2012 The Eleventh International Conference on Computational Structures Technology”, Dubrovnik, Croatia

04.11-07.1.2012 - First International Conference for PhD students in Civil Engineering “New Researcher Generation with Challenges in Civil Engineering” CE-PhD 2012, 4-7 November 2012, 

14.11-15.11.2012 - „The 3rd Conference of the Young Researchers”14-15 Nov. 2012, Bucharest, Romania

17.11-18.11.2012 - 2nd International Conference on Civil Engineering and Building Materials (CEBM 2012), Hong Kong, China

3.4. YEAR 2013

3.4.1 Objectives/activities 2013

O1: Experimental test on singe storey pitched roof portal frames, with lateral restraints – II-nd phase

A1.1. Supply of the experimental specimens

A1.2 Execution of experimental tests

A1.3 Interpretation of results

A1.4 Articles in ISI and BDI, and attendance in specialized international conferences in the field

O2: Calibration and parametric study on the behavior pitched roof portal frames made of elements with variable cross sections

A2.1. Documentation

A2.2 FEM analysis – calibration of the computational model

A2.3 Comparison of the results analytic-FEM

A2.4 Articles in ISI and BDI, and attendance in specialized international conferences in the field

O3: Elaboration of the final research report

  A3.1. Elaboration of the final research report and publication of it in a publication recognized by CNCSIS

3.4.2 Achieved results 2013

Experimental tests – general dimensions of the specimen

 

Fig. Experimental set-up

C160-6-NR	C160-8-NR	C180-6-NR	C180-8-NR

Fig. Failure mode of the tested specimen

Fig.  Behavior curve –experimental tests

3.4.3 Published papers 2013

M. Cristutiu, D. Nunes, A. Dogariu - Steel members with variable I cross sections under bending and compression with lateral restraints- behaviour by experimental test. Proc. Of Design Fabrication and Economy of Metal Structures 2013, MisKolc-Hungary, April 24, 2013 – April 26, 2013

M. Cristutiu & D. Nunes - Advanced FEM analysis of steel pitched-roof portal frames with tapered members. Advanced Materials Research Vol. 710 (2013) pp 358-361 © (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.710.358

M. Cristutiu & A. Dogariu - Local and global stability of I steel members with tapered web via advanced nonlinear analysis. Advanced Materials Research Vol. 710 (2013) pp 372-375 © (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.710.372.

M. Cristutiu & D. Nunes - Experimental tests on steel members with variable I welded section, Proc. Of. 2-nd International Conference of Structures and Architecture. STRUCTURES AND ARCHITECTURE – Concepts, Applications and Challenges, Guimaraes, Portugalia, 24-26 iulie 2013, acceptata spre publicare. CRC Press/Balkema

M. Cristutiu & D. Nunes - Influence of the cross section slenderness on the buckling behaviour of steel welded tapered beam-column, THE F IFTH I NTERNATIONAL C ONFERENCE ON S TRUCTURAL E NGINEERING , MECHANICS AND C OMPUTATION   (SEMC 2013 )  CAPE T OWN , S OUTH A FRICA. − 2-4 S EPTEMBER 2013, accepted for publication, CRC Press/Balkema

M. Cristutiu & D. Nunes - Behaviour of pitched-roof portal frames with tapered web and flange members considering lateral restraints. THE F IFTH I NTERNATIONAL C ONFERENCE ON S TRUCTURAL E NGINEERING , MECHANICS AND C OMPUTATION   (SEMC 2013 )  CAPE T OWN , S OUTH A FRICA. − 2-4 S EPTEMBER 2013, accepted for publication, CRC Press/Balkema

3.4.4 Conference attendance 2013

24.07-26.07 2013- ICSA 2013 -2-nd International Conference of Structures and Architecture. STRUCTURES AND ARCHITECTURE – Concepts, Applications and Challenges, Guimaraes, Portugalia, 24-26 iulie 2013

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