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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 multi‐level 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 a general‐purpose nonlinear structural analysis software and comparisons with experimental results are discussed in a companion paper

Nowadays, safety assessment under seismic loading of historical masonry buildings, such as ancient churches, is an actual and important topic due to the potential human and economic losses involved even for a partial collapse. Therefore, the prevention and mitigation of their seismic risk would result the best intervention for preserving in the future these monuments of inestimable value. To date, in literature many methods are available for evaluating the seismic vulnerability and the related risk. In particular, this study focuses on the first two simplified evaluation methods proposed by the current Italian directive containing the guide lines for assessment and reduction of cultural heritage seismic risk. The methods, having an increasing precision level, may be applied in sequence at a different scale for screening and identifying the present priorities, and for designing the required interventions. In this article, these methods are applied to five ancient masonry churches located within the UNESCO site of the "Sassi" of Matera (Italy), a seismic-prone area with moderate seismicity. Afterward, also a new simplified method is applied, in the form of fast appraisal method useful for preliminary ranking the seismic performances of the case studies at a territorial scale.

In this paper the implementation and validation of a modified steel bar model including bond‐slip of longitudinal bars proposed in a companion paper is discussed. The model is developed on the key assumption of linear slip field along the steel bar with different configurations at the ends of the bar. It is demonstrated that the simplified model is capable of predicting the axial slip displacement with suitable accuracy compared to a refined model but with considerably fewer computational steps. The proposed model avoids nested iterations in the context of fiber model discretization of a section that requires the representation of all actions in terms of stress and strain. The model is applied to two component tests — one with poor and another with improved reinforcing detailing. Findings from the simulations indicate that the proposed model is more suitable for use in connections with poor detailing and pronounced slip in the plastic hinge zones