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

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4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS The transfer of the compression force from the slab, on the sagging moment side, can only take place through the two mechanisms described above. The highest resistance FRd offered at a beam-to-column connection can be estimated as the sum of FRd1 and FRd2: F = F 1 + F 2 = ( b + 0.7 ⋅ h ) ⋅ t ⋅ f ( 4.11 ) Rd Rd Rd c c slab cd Then, the effective width of concrete in the connection zone is, at the most: b = b + ⋅ h ( 4.12 ) eff , conn c 0.7 c In general beff,conn
4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS 116 • Joint panel zones often develop a maximum strength that is significantly greater than the strength at first yield. This additional strength has been attributed to strain hardening and to contributions of the column flanges in resisting panel zone shear forces. Large inelastic panel zone deformations are typically required in order to develop the maximum panel zone strength. • Panel zone deformations can add significantly to the overall deformation of a moment resisting frame, for both elastic and inelastic ranges of behaviour. • Panel zone stiffness and strength can be increased by the attachment of web doubler plates to the column within the joint region. The effectiveness of doubler plates is affected by the method used to connect them to the column. • In the inelastic range, panel zones can exhibit very ductile behaviour, both for monotonic and cyclic loading. Experimentally observed hysteresis loops are typically very stable, even at large inelastic deformations. Current US building code provisions (AISC, 1997; FEMA 350, 2000) permit the formation of plastic hinges in the panel zones of steel moment frames under earthquake loading. Thus, rather than forming plastic flexural hinges only in the beams or columns, a primary source of energy dissipation in a steel moment frame can be the formation of plastic shear hinges in the panel zones. Consequently, an accurate analytical model is needed to predict the response of the panel zone in order to predict accurately the response of a steel moment frame under earthquake loading,. The traditional center-to-center line representation of the frame must be modified to include panel zone deformation in frame analysis. Several researchers, including Krawinkler et al. (1971) and Wang (1988) proposed relationships between panel zone shear force V and panel zone deformation γ for monotonic loading. These relationships have been used as the basis of mathematical models for non-linear rotational springs representing the panel zone. Krawinkler’s V–γ relations have been adopted in several building codes (ICBO, 1997; AISC, 1997) as a basis for computing the shear strength of panel zones. However, it was pointed out by Krawinkler that a new model might be needed for joints with thick column flanges since his V–γ relations were derived from experimental and analytical results for panel zones with relatively thin column flanges. Wang also showed that Krawinkler’s V–γ relations may overestimate panel zone shear strength for panel zones with thick column flanges. The mathematical model for strength and stiffness calculations is shown in Figure 4.12. It consists of an elastic-perfect plastic shear panel surrounded by rigid
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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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