Antonello De Luca

Behaviour And Modelling Of Masonry ChurchBuildings In Seismic Regions

In this paper a church building characterised by a basilica plan is investigated for deriving indications on its vulnerability to seismic actions. Linear analysis of the fiill 3D model of the complex structural system is carried out through FEM in the static and dynamic case. The results of the analysis in terms of elastic demand on the different 2D elements identified in the 3D model and constituting the church are then compared to the ultimate capacity of the single 2D elements. The effect of a frequently used upgrading procedure consisting in the insertion of rigid diaphragms at different levels is also investigated. The results of the study, applicable to this specific case study, but somehow extendable to other basilica type churches characterised by similar global structural properties, confirm the susceptibility of these buildings to extensive damage and possibly to collapse, and therefore the need of upgrading interventions. The insertion of rigid diaphragms has not proved to be a surely efficient means for increasing the seismic capacity of the building.

Restoration Through a Traditional Intervention of a Historic Unreinforced Masonry Building “Palazzo Scarpa” in Naples

A challenging retrofit intervention, through traditional methodology, on an existing unreinforced masonry building “Palazzo Scarpa” is illustrated. Especially challenging was the complete substitution of the two storeys of two existing longitudinal walls, each long 20m, for a total of 30 piers, by leaving in place the three upper storeys due to need of not evacuate the 36 families living in the building. The diagnosis phase demonstrated an unacceptable low value of the safety factor of the structure under gravity loads. Vertical cracking in several walls, due to compression stresses, confirmed this worrying safety condition of the masonry structure. The paper demonstrates the feasibility (technical and economical) of very traditional intervention, completely based on real mechanical insertions: the substitution walls and the mechanical steel ties. In 2007, the interventions illustrated in this study won the first prize of Sisto Mastrodicasa award on restoration and strengthening of buildings.

Nonlinear Analysis Of Some Typical Elements Of ABasilica Plan Church

In this paper the strength and deformation capacity of the main structural elements of a basilica church are studied via static nonlinear analysis. In particular, the nave arcades, the cross section at the triumphal arch and the end wall of chancel are analysed through FEM, using the general purpose software program ABAQUS. The push-over analyses performed on the main structural elements of the church provide useful information on the non-linear behaviour, the stress pattern, the collapse mode and the ultimate strength. These information are particularly valuable since the structural schemes herein analysed are very repetitive within basilica type churches, which represent a large portion of the Italian cultural heritage. The results, in terms of ultimate loads, have been compared with the collapse loads obtained through the application of the limit analysis. This comparison has allowed to demonstrate the capacity of ABAQUS code to provide reliable results and to investigate on the effect of material properties on the ultimate capacity.

Seismic Behavior of some Basilica Churches after L’Aquila 2009 Earthquake

In this paper the seismic response of four church buildings in the l’Aquila April 2009 earthquake is analyzed. The buildings are: St. Giusta church, St. Maria di Collemaggio Basilica, St. Silvestro church and St. Pietro di Coppito church. The analyses are carried out by employing a “two-step” procedure suggested by the authors and already applied to similar case studies. The first step consists in three-dimensional linear analysis, while in the second step, two-dimensional non-linear analyses of macro-elements are carried out. The results coming from the two-steps, allow for understanding the observed damage and for approximately assessing the seismic level of the building.

Cyclic behaviour of beam-to-column welded connections

In this paper the results of an experimental program devoted to the assessment of the cyclic behaviour of full scale, European type, beam-column subassemblages with welded connections are presented. Six tests (five cyclic and one monotonic) have been carried out on three different series of specimens, encompassing a total of eighteen tests. The three specimen series have been designed with the aim of defining the effect of the column size on the connection behaviour, under different applied loading histories. The tests have evidenced the effect of the column size and panel zone design and of the applied loading history on the cyclic behaviour and failure modes of the connections.

Seismic behaviour of perimeter and spatial steel frames

The present study deals with the seismic performance of partial perimeter and spatial moment resisting frames (MRFs) for low-to-medium rise buildings. It seeks to establish perimeter configuration systems and hence the lack of redundancy can detrimentally affect the seismic response of framed buildings. The paper tackles this key issue by com-paring the performance of a set of perimeter and spatial MRFs, which were “consistently designed”. The starting point is the set of low-(three-storey) and medium-rise (nine-storey) perimeter frames designed within the SAC Steel Project for the Los Angeles, Seattle and Boston seismic zones. Extensive design analyses (static and multi-modal) of the perimeter frame buildings and consistent design of spatial frame systems, as an alternative to the perimeter configuration, were conducted within this analytical study. The objectives of the consistent design are two-fold, i.e. obtaining fundamental periods similar to those of the perimeter frames, i.e. same lateral stiffness under design horizon-tal loads, and supplying similar yield strength. The seismic behaviour of perimeter and spatial configuration structures was evaluated by means of push-over non-linear static analyses and inelastic dynamic analyses (non linear time histories). Comparisons be-tween analysis results were developed in a well defined framework since a clear scheme to define and evaluate relevant limit states is suggested. The failure modes, either local or global, were computed and correlated to design choices, particularly those concerning the strength requirements (column overstrength factors) and stiffness (elastic stability indexes). The inelastic response exhibited by the sample MRFs under severe ground motions was assessed in a detailed fashion. Conclusions are drawn in terms of local and global performance, namely global and inter-storey drifts, beam and column plas-tic rotations, hysteretic energy. The finding is that the seismic response of perimeter and spatial MRFs is fairly similar. Therefore, an equivalent behaviour between the two configurations can be obtained if the design is “consistent”.

Structural Analysis of the Basket Dome in the Chapel of the Holy Shroud by Guarino Guarini

ABSTRACT This article provides the structural analysis of the basket dome in the Chapel of the Holy Shroud, designed by Guarino Guarini in 1667. The dome is characterized by two structural systems: twelve massive ribs and thirty-six elliptical arches, organized in six superimposed levels. A FE brick model, analyzed considering both a linear and a nonlinear material constitutive law, was compared with a simplified model consisting of beam elements. Further analyses were carried out on simplified models, in order to clear up the roles played by arches and ribs. On this issue, the existent studies on the Chapel do not provide always the same interpretation: some references state the ribs as only load-bearing system of the dome, while others give to the arches a leading role. The paper provides a significant contribution, assigning a specific role to both elements by means of observational, historical and numerical analyses.

Cyclic Behaviour of Beam-to-Column Welded Connections

Publisher Summary This chapter focuses on an experimental program on welded beam-to-column connections aimed at evaluating the effect of the column dimensions and panel zone design on the cyclic behavior, ultimate strength, and deformation capacity of the welded connections, varying the applied loading history. A total of 18 beam-to-column fully welded joints are designed, fabricated, and tested up to failure under different loading histories. The specimens, made of S235 JR steel, are T-shaped beam-column subassemblages, consisting of a 1000 mm long beam and 1800 mm long column. In the three types of specimens—respectively appointed as BCC5, BCC6, and BCC8–the beam cross-section is the same, while the column cross-section is varied, being respectively HE160B for the BCC5 series, HE200B for the BCC6 series, and HE240B for the BCC8 series. The basic monotonic stress-strain curve and the mechanical properties of the specimen steel components are determined through coupon-tension tests. The values of the total rotation capacity, in the increasing amplitude test, reach 0.064 rad for the BCC5 specimen, 0.053 rad for the BCC6 specimen, and 0.046 rad for the BCC8 specimen. These values correspond to low values of beam plastic rotations, respectively, equal to 0.0057, 0.0175, and 0.0242 rad for the three specimens, thus confirming that large rotations can be experienced due to the column web panel deformations.