Rivera J.A.,Rose School |
Petrini L.,Polytechnic of Milan
Bulletin of Earthquake Engineering | Year: 2011
Performance-Based Seismic Design is now widely recognized as the pre-eminent seismic design and assessment methodology for building structures. In recognition of this, seismic codes may require that buildings achieve multiple performance objectives such as withstanding moderate, yet frequently occurring earthquakes with minimal structural and non-structural damage, while withstanding severe, but rare earthquakes without collapse and loss of life. These objectives are presumed to be satisfied by some codes if the force-based design procedures are followed. This paper investigates the efficacy of the Eurocode 8 force-based design provisions with respect to RC frame building design and expected seismic performance. Four, eight, and 16-storey moment frame buildings were designed and analyzed using the code modal response spectrum analysis provisions. Non-linear time-history analyses were subsequently performed to determine the simulated seismic response of the structures and to validate the Eurocode 8 force-based designs. The results indicate the design of flexural members in medium-to-long period structures is not significantly influenced by the choice of effective member stiffness; however, calculated interstorey drift demands are significantly affected. This finding was primarily attributed to the code's enforcement of a minimum spectral ordinate on the design spectrum. Furthermore, design storey forces and interstorey drift demand estimates (and therefore damage), obtained by application of the code force-based design procedure varied substantially from those found through non-linear time-history analysis. Overall, the results suggest that though the Eurocode 8 may yield life-safe designs, the seismic performance of frame buildings of the same type and ductility class can be highly non-uniform. © 2011 Springer Science+Business Media B.V.
Palermo A.,University of Canterbury |
Heux M.L.,Rose School |
Bruneau M.,State University of New York at Buffalo |
Anagnostopoulou M.,State University of New York at Buffalo |
And 2 more authors.
Bulletin of the New Zealand Society for Earthquake Engineering | Year: 2010
On September 4, 2010 a M 7.1 earthquake occurred with an epicentre near the town of Darfield 30-40 km west of the Christchurch CBD. In the days following the earthquake inspections were carried out on highway, road City Council and pedestrian bridges in the Canterbury area. This paper details the preliminary findings based on visual inspection of about fifty five bridges. The paper comprises information supplied by consulting engineering firms which were also directly involved in the inspections soon after the earthquake.
Pennucci D.,Rose School |
Sullivan T.J.,University of Pavia |
Calvi G.M.,Institute for Advanced Study
Journal of Earthquake Engineering | Year: 2011
The estimation of the maximum inelastic displacement response of structures is gaining increasing importance with the development and application of the so-called Performance-Based Design (PBD) procedures, in which important performance criteria are directly correlated to the seismic displacement demand. The maximum displacement of a MDOF structure is often estimated using the equivalent SDOF system concept, which reduces the problem to the prediction of the maximum inelastic displacement demand of an equivalent SDOF system with characteristics representative of the MDOF structure. This study focuses on the nonlinear response of SDOF systems with medium and long periods (T >1 s), typical of tall buildings for which PBD is more widely adopted. In particular, the effect of several characteristics on the nonlinear response of the equivalent SDOF is investigated, such as structural period, ground motion spectral shape, sensitivity of spectral shape to damping, and elastic damping ratio. Design equations for the prediction of the max SDOF inelastic displacement accounting for all the identified influencing parameters, and based on the newly introduced Displacement Reduction Factor (DRF) concept, are proposed. Copyright © A. S. Elnashai &N. N. Ambraseys.
Attanasi G.,Rose School |
Auricchio F.,University of Pavia
Journal of Earthquake Engineering | Year: 2011
The objective of the present work is to propose a new seismic isolation device based on superelastic material components manufactured using shape memory alloys. Seismic isolation is one of the most effective options for the passive protection of structures. Shape memory alloys (SMAs) are characterized by unique mechanical properties due to a solid-solid transformation. An isolation bearing system based on a SMA superelastic effect is intended to provide nonlinear flag-shaped lateral displacement-shear force hysteresis, additional damping, and recentering properties to reduce or eliminate the residual deformations. The device concept is based on two separate systems, one to transmit the vertical load and another to act as a lateral restrainer. This article presents in detail the mechanical components of the innovative device focusing on its main properties. The system theoretical response is computed, resulting very attractive from the earthquake engineering point of view, because of its capability in reaching the design goals, i.e., modification of the structural response, ability to undergo large displacement demand without loss of strength, energy dissipation, and recentering after the seismic event. Copyright © A. S. Elnashai &N. N. Ambraseys.
Ahmad N.,Rose School |
Ahmad N.,University of Peshawar |
Ali Q.,University of Peshawar |
Umar M.,University of Peshawar
Bulletin of Earthquake Engineering | Year: 2012
This paper presents simplified engineering tools for seismic analysis of traditional Dhajji-Dewari structures, a concentrically braced timber frame with masonry infill, within the context of vulnerability assessment of existing stock, strengthening and restoration of historical heritage and feasibility analysis of future construction projects. Similar like structures can be found in various parts of America, Asia, Europe and the Middle-East. The study included tools for the evaluation of lateral force-deformability characteristics of Dhajji walls using non-linear static pushover analysis, simplified models for nonlinear dynamic time history analysis of Dhajji wall structures subjected to ground shaking, and simplified models for seismic performance evaluation of Dhajji wall structures using hand calculations. Three full scale Dhajji walls tested quasi-static-cyclically, with additional 18 tension and bend tests on timber frame connections, at the Earthquake Engineering Center of Peshawar are analyzed to understand the damage mechanism and salient features of the system in resisting lateral load, retrieve lateral force-deformability behavior, hysteresis response and viscous damping (energy dissipation) of Dhajji walls in order to calibrate tools for nonlinear static and dynamic seismic analysis of Dhajji wall structures. Applications are shown on the seismic performance assessment of example structures and design of new construction schemes. The findings from the present research study can provide help on the seismic performance evaluation of similar like concentrically braced timber frame masonry wall structures. © 2012 Springer Science+Business Media B.V.