Michelangelo Laterza

ABSTRACT This paper presents a simplified model for describing the response of a longitudinal bar embedded in concrete, taking into account the bond-slip phenomenon. The model is developed by assuming a linear bond-slip field along the bar anchorage length and provides a simplified stress-strain relationship to assign to the longitudinal reinforcement. The analytical approach adopted makes the proposed model very convenient from a computational standpoint because, unlike many other refined models, it does not require a multilevel iterative process. Moreover, the assumptions made are particularly appropriate for modeling bond-slip of smooth bars generally used in older reinforced concrete buildings. The implementation strategy of the proposed bond-slip model in general-purpose nonlinear structural analysis software and comparisons with experimental results are discussed in a companion paper.

ABSTRACT The paper shows results of two non-linear cyclic analyses performed with OpenSees where slippage phenomenon of longitudinal bars is pronounced. Bond-slips have modeled by using the simplified model proposed by Braga et al. which assigns an equivalent stress-strain relationship to longitudinal steel accounting for both material elongation and relative slip. The model is also capable to take into account anchorages at bars ends (such as bends or hooks) and has been developed mainly for assessing older existing buildings where, because of the presence of reinforcing plain bars, bond-slips are particularly pronounced. Unlike many other refined models published in literature, the analytical formulation of the proposed model requires a minimum computational effort avoiding any nested iterations loop in the context of fiber model discretization of a section.

Nowadays comprehensive management plans are needed for conserving and protecting in high natural risks-prone areas the immovable cultural heritage.
In a previous work a seismic risk assessment procedure was proposed, established by applying two different designing tools addressed to define: seismic vulnerability assessment (Designing Tool 1) and hazard characterization and mapping (Designing Tool 2).
The seismic vulnerability has been evaluated taken into account some structural indicators such as: the building position and the characteristics of its foundations; geometry in plan and in elevation; distance between walls; the type and quality of the resistant system; horizontal and covering structures; the conservation status; alternation in the construction system and in the environment; vulnerability to fire and the presence of secondary elements that could fall after a quake.
On the other hand, the seismic hazard is evaluated also including other threats such as: landslides, erosion, physical stress, volcanic, urban fire, air pollution, hydro meteorological threat and scarce maintenance, making a hierarchy according to the severity of potential damage on the Cultural Property that can increase seismic risk. In this paper some applications to case studies of the proposed procedure are shown. In particular, are performed the seismic risk evaluations of a Chilean and an Italian old masonry churches, both built under the Hispanic Monarchy in both countries between the XVII and XVIII centuries.

Nowadays comprehensive management plans are needed for conserving and protecting the immovable cultural heritage in high natural risks-prone areas. In a previous work a seismic risk assessment procedure was proposed, established by applying three different tools addressed to define: seismic vulnerability assessment, hazard mapping and prioritizing assistance based on cultural value. In this paper some applications to case studies of the proposed procedure are shown. In particular, are performed the seismic risk evaluations of two Chilean and two Italian old masonry churches. The seismic vulnerability has been evaluated taken into account some structural indicators such as: the building position and the characteristics of its foundations; geometry in plan and in elevation; distance between walls; the type and quality of the resistant system; horizontal and covering structures; the conservation status; alterations in the construction system and in the environment; vulnerability to fire and the presence of secondary elements that could fall after an earthquake. The seismic hazard is evaluated also including other threats such as: landslides, erosion, physical stress, air pollution, socio-organizational and scarce maintenance, making a hierarchy according to the severity of potential damage on the Cultural Property that can increase seismic risk.

The conservation of historic buildings cannot be independent of the knowledge of its constitutive features such as: materials, constructive techniques, structural characteristics and building evolution, representing a crucial point for the assessment of seismic risk. In this paper, a procedure for the typological characterization and two simplified procedures for seismic risk assessment are described and critically applied to case studies of churches belonging to the "Sassi of Matera", the historic center of Matera town protected by UNESCO. This methodology is intended to be used at a territorial scale for the planning of preventive conservation of cultural heritage and seismic risk mitigation projects. The obtained results are shown and compared among them, highlighting the aspects that characterize their seismic vulnerability.

Dramatic human and economic consequences are nowadays still resulting from natural and anthropic risks of Cultural Heritage. Matera landscape is characterized by many and important ancient masonry cathedrals, concentrated in its downtown named " Sassi of Matera " , and recognized as Cultural World Heritage by UNESCO since 1993. The city is located in the southern Italy into a seismic-prone area with moderate seismicity. The structural typology and materials identification of these churches represent a crucial point for their structural safety assessment and risks mitigation. In this paper some representative examples are illustrated by remarking the main peculiarities of such structures. Then, some chosen study cases are evaluated with simplified procedures for seismic risk assessment. This approach may be also used in a territorial scale for planning the preventive conservation of the Cultural Property, in order to establish priorities lists and to plan preventive mitigation projects based on the specific vulnerabilities of the cases under consideration.