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The paper presents and discusses seismic fragility functions of code-conforming buildings in Italy. The structures under consideration are taken from those considered by a large Italian research project (RINTC), aiming at evaluating the seismic reliability of new-design buildings. Design refers to a variety of structural typologies (i.e. un-reinforced masonry, reinforced concrete, steel, and precast concrete buildings) and configurations (e.g. number of stories, floor plan, and the presence of infills), as well as to sites with different hazard levels and local site conditions. The seismic fragility of the structures is evaluated via multiple-stripe nonlinear dynamic analysis using the equivalent-single-degree-of-freedom (ESDoF) systems calibrated based on pushover analysis of the three-dimensional structural models. The seismic response of the ESDoF models is also validated in terms of demand-capacity ratio and risk of failure compared to those of the three-dimensional structural models. Along with providing fragility curves for the buildings located at high-hazard sites, the study discusses the issues that significantly affect the fragility assessment for those located at low-to-mid hazard sites. [ABSTRACT FROM AUTHOR]

Multistoried masonry infilled concrete (RC) frame with open ground storey has been recognized as a serious stiffness irregularity that has led to typical soft storey collapse of many buildings in past seismic events. Present study represents extensive static and dynamic analyses to investigate the seismic behavior of masonry infilled soft storied RC buildings. Several soft storied 2D frames with variation in number of storeys, number of spans, percentage of infilled frame panels, height to horizontal extent ratio as well as randomness of infill positions have been analyzed and the behavior of frames is investigated. Effect of variation of these parameters on base shear, natural period of vibration, storey drift etc. are studied. Results show that the base shear is significantly increased in presence of structurally active infill panels as compared to static analysis while randomness in the distribution of infill shows no appreciable influence. The findings show that seismic forces obtained from static analysis leads to significantly under-designed ground storey columns in soft storey buildings and are vulnerable during earthquake. Magnification of base shear as a function of amount of infill number of storeys are presented which may act as a guideline for the engineers towards safer design of columns and other elements of buildings with open and soft ground storey in a rational manner. [ABSTRACT FROM AUTHOR]

Many existing reinforced concrete (RC) structures around the world have been designed to sustain gravity and wind loads only. Past earthquake reconnaissance showed that strong earthquakes can lead to substantial damage to non-seismically designed RC buildings, particularly to their beam-column joints. This paper presents a novel retrofit method using buckling-restrained haunches (BRHs) to improve the seismic performance of such joints. A numerical model for RC joints is introduced and validated. Subsequently, a new seismic retrofit strategy using BRHs is proposed, aimed at relocating plastic hinges and increasing energy dissipation. The results indicate the retrofit method can effectively meet the performance objectives. [ABSTRACT FROM AUTHOR]

Most of buildings and structures are usually projected according to two main axes. However, the geographical position of these buildings varies randomly. Such random distributions of the azimuthal positions of structures, in most of the cities, generally, are not accounted for when assessing their seismic risk; certainly, the direction of the seismic loads is another highly random variable. Moreover, an additional important source of uncertainty is related to the structural response, mainly due to the random character of the mechanical properties. There is a consensus that uncertainties must be considered for adequately assessing the seismic risk of structures, but these directionality effects have not been deeply explored so far. In this article, the influence of the high uncertainty involved in these input variables on the expected seismic damage is analysed. Thus, an actual earthquake, which affected the southern part of Spain, is studied. Notably, damages on a group of affected buildings, located close to the epicentre, are analysed and discussed in detail. The results show that the influence of the random azimuthal position of structures is an important source of uncertainty and that it should be taken into account when estimating the expected seismic risk in urban areas. [ABSTRACT FROM AUTHOR]

This study investigates the seismic response of reinforced concrete buildings designed according to the current Italian building code. Number of stories, site hazard, presence and distribution of masonry infill panels, and type of lateral resisting system are the key investigated parameters. The main issues related to design and modeling are discussed. Two Limit States are considered, namely Global Collapse and Usability-Preventing Damage. The main aim of the study is a comparison between the seismic response of the buildings, investigated through nonlinear static and dynamic analyses. Irregularity in the distribution of infill panels and site hazard emerge as the most influential parameters. [ABSTRACT FROM AUTHOR]