Analysis and modelling of the seismic behaviour of high ... - Ingegneria

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5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES contractors. The in-fills force the RC structure above the first storey to act as a rigid body, thus the significant seismic forces and deformations shift in the columns of the lowest storey where the in-elastic buckling take place (see Figure 5.3). Considering also the low shear resistance belonging to RC members in general, it is immediate to understand why the first storey columns fail when subjected to cycling loading, generating the global structural collapse indeed. In-fill walls Earthquake "Soft Storey" BEFORE AFTER Figure 5.3. Sketch explaining the “Soft Storey Mechanism” Plastic Hinges The proposed idea is to use encased steel section as ductile fuses able to dissipate cyclically the energy of the earthquake in the lower storeys of buildings which otherwise remain reinforced concrete buildings. The objective is to promote safety for the people without too much changing the constructional practice of RC structures. This way to set the problem is intended to be the most effective for an easy gain in the structural reliability in those areas where the civil engineering market mainly considers the use of cement, gravel and water The research can be subdivided into a set of four operational tasks: • Task 1: definition by calculations of H steel sections able to substitute reinforced concrete column of typical sizes, without working in a composite way with concrete; • Task 2: definition, execution and analysis of tests aiming to set forward the composite shear resistance of encased steel sections in zone of columns submitted to cyclic plastic bending; • Task 3: definition of a computation method of the shear resistance of composite columns submitted to cyclic bending; 177
5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES • Task 4: definition of design rules and preparation of a design tool for 178 practice: Tables of H steel sections able to substitute reinforced concrete column of typical sizes, considering a minimum composite activation. The seismic design of the columns embedding steel profiles, successively verified on the basis of experimental tests, has been executed by using the rules included in the following standards: • prEN 1991-1-1:2001 “Actions on structures, Part 1-1: general actions, densities, self-weight, imposed loads for buildings” - Final Draft, July 2001; • prEN 1992-1:2001 “Design of concrete. Part 1: general rules and rules for buildings” –Draft n° 2, January 2001; • prEN 1993-1-1:2000 “Design of steel structures. Part 1.1: general rules” Draft n° 2, August 2000; • prEN 1994-1-1:2001 “Design of composite steel and concrete structures. Part 1-1: general rules and rules for buildings” – Draft n° 3, March 2001; • prEN 1998-1:2001 “Design of structures for earthquake resistance. Part 1: general rules, seismic actions and rules for buildings” –Draft n°3, May 2001. Moreover, the steel profiles for strong and weak axis bending have been chosen by matching simple design criteria developed at the University of Liege. They should aim to provide a simple constructional measure, which obviate the soft storey type failure of a building. This constructional measure should: • provide ductility; • provide a column which, at the ultimate stage where concrete would be locally crushed in plastic hinges, the steel section would provide enough axial strength and a plastic moment and a stiffness similar to those of the reinforced concrete column. From the obtained knowledge on joint and member responses, a numerical FE model of the beam-to-column joint sub-assemblage has been developed to examine its seismic behaviour through non-linear analyses. This analytical work permitted to predict the performance of the joint and to propose appropriate analytical formulas for the estimation of the yield and ultimate strength both of the columns and of the beam-to-column joint subjected to very high seismic shear forces.
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Dipartimento di Ingegneria Meccanic
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UNIVERSITÀ DEGLI STUDI DI TRENTO D
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Ai miei genitori
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INDEX 1 INTRODUCTION...............
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INDEX iii 4.10.3 Results of the PsD
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1.1 Introduction 1 1 INTRODUCTION I
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1. INTRODUCTION imposes precise con
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1. INTRODUCTION joints whilst 2D mo
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7 2 DUCTILITY AND SEISMIC RESPONSE
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2. DUCTILITY AND SEISMIC RESPONSE O
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3. SEISMIC BEHAVIOUR OF BOLTED END
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4. SEISMIC RESPONSE OF PARTIAL-STRE
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5. SEISMIC BEHAVIOUR OF RC COLUMNS
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6. SUMMARY, CONCLUSIONS AND FUTURE
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Analysis and modelling of the seismic behaviour of high ... - Ingegneria

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