Giorgio Serino

Axial Force-Bending Moment Limit Domain and Flow Rule for Reinforced Concrete Elements Using Euro Code

Performance-based design approach of special moment-resistant reinforced concrete (RC) framed structures demands a thorough understanding of axial force—bending moment (P—M) yield interaction of RC elements, particularly when the structure is subjected to seismic loads. Latest design approach includes desirable features of both ultimate strength and working stress to ensure a suitable ductile deformation response. This demands a detailed understanding of nonlinear response of P—M interaction. A complete set of analytical expressions for P—M yield interaction are proposed in a closed form by defining the limit boundary with ten sub-domains based on Euro Code currently in prevalence. P—M interaction relationships are also verified for plastic flow-rule in two main sections namely: (i) tension failure resulting in yielding of steel; and (ii) compression failure resulting in crushing of concrete. The conventional limit P—M domain is described based on Euro Code as long as the plastic strain increment becomes nearly normal to the yield domain over the part of bending response in the presence of axial force. The verified flow rule shows a close agreement in all sub-domains of tension failure, while does not qualify in few of the sub-domains of crushing failure. Practical examples of RC sections are chosen to illustrate the influence of different parameters namely: (i) cross-section dimension; (ii) percentage of tension and compression reinforcements; and (iii) properties of constitutive materials on the P—M boundary. Mathematically developed P—M interaction model is capable of identifying the damage mechanism of different sub-domains in RC sections; damage identification is made on the basis of strain profile of concrete and reinforcing steel.

Application of structural isolation and health monitoringThe ‘Our Lady of Tears Shrine’ in Syracuse (Italy)

The paper describes the seismic retrofit (carried out in the period February to March 2006) of the ‘Our Lady of Tears Shrine’ in Syracuse (Italy), made bysubstituting the bearings supporting its impressive dome with sliding seismic isolators equipped with elasto-plastic dissipators. After an accurate description of the construction and of its new antiseismic devices, installed between the dome and its 22 supporting columns, the dome raising and lowering phases, together with the instrumentation and data acquired during the operations, are reported in detail. The improvement of the structural behaviour after the seismic retrofit is demonstrated through the results of a numerical investigation under seismic excitation. Finally, the rehabilitation and reactivation of the pre-existing continuous monitoring system of the temple is examined. The structure has been recently included among those of the Italian network of buildings and bridges permanently monitored by the Italian Department of Civil Protection.

A Base Isolation System for Developing Countries Using Discarded Tyres Filled with Elastomeric Recycled Materials

This article studies the performance of economic base isolators using tyres filled with elastomeric recycled materials. The research was conducted to analyze base isolators to be used in developing nations, where the application of conventional elastomeric rubber bearings due to economic reasons is limited. The tested isolators are made of kart tyres filled with different recycled elastomeric materials and aggregates. Dynamic and static tests proved acceptable vertical to horizontal stiffness ratio of the bearings and shake table tests showed an excellent enhancement of the base isolated structural response compared to the corresponding fixed base structure.

An extended Kalman Filter procedure for damage detection of base-isolated structures

Base isolation is widely adopted to mitigate earthquake effects on structures. Information concerning the status of the isolation devices is fundamental, for example, after an emergency event and, consequently, damage detection procedures have received significant attention in the recent years. Herein, an extended Kalman filter approach is developed for real-time estimation of the isolation device stiffness from acceleration measurements. Simulations have been carried out by means of a three degree of freedom model and results are illustrated. Moreover, experimental evaluations of the damage detection method have been conducted by means of a prototype structure that has been excited adopting a sequence of seismic events. The results highlight a stiffness degradation and fully agree with the measurements, allowing a validation of the technique.

Design and Retrofit of Multistory Frames with Elastic-Deformable Viscous Damping Braces

ABSTRACT This paper provides an exhaustive treatment for the analysis of non-proportional damping structures equipped with elastically deformable viscous damping braces. A frequency domain approach is adopted for solving the equation of motion as a function of nondimensional parameters. Accounting for the brace flexibility, an optimal damping system is suggested in order to minimize the resonance peak of the top-story displacement response on the first vibration mode. The effect of variation of the dissipative bracing system is demonstrated not only in terms of provided equivalent viscous damping and maximum response, but also in terms of dominant frequency and mode shapes.

An application of SHMS to a passively controlled structure

This paper is focused on the study of the “Our Lady of Tears Shrine” in Syracuse, which was subjected to a seismic isolation intervention and the successive installation and management of a structural monitoring system. The monitoring system, representing an upgrading and improvement of an old system never made working, has some innovative features, because it allows to manage with one and the same dedicated hardware and software both the slow (thermal variations, relative humidity, wind direction and velocity) and the fast acquisitions, namely those dynamiccaused by earthquake, wind and environmental vibrations. The monitoring system has been recently inserted among those structures maintained and controlled by the National Department of Civil Protection within the Seismic Observatory of Structures. Some records of recent low magnitude seismic events allowed to validate the correct behavior of the whole structure, as well as to make a dynamic identification of the complex construction. A complex FEM model has been used to predict the structural behavior under strong motions and evaluate the effectiveness of the seismic retrofit.