LEARNING OUTCOMES

The course deals with the safety assessment of existing buildings. Differently from the perspective of design of new constructions, the behavior of the structure is unknown at the beginning of the analysis requiring effective procedures to face the problem of such incomplete knowledge that involves both aleatory and epistemic (e.g. related to the effectiveness of structural details) uncertainties. The course faces both issues related, on the one hand, to the diagnosis to ordinary actions and, on the other, to the prevention against rare events. The wide variety of behaviors that characterize no standardized existing buildings makes more conventional the use of methods of analysis quite common in the design of new structures, such as the linear ones. For this reason, the course devotes large attention to the nonlinear static procedures. Finally, among rare actions, since existing buildings have been often conceived without specific rules for the seismic action, such vulnerability constitutes one of most relevant which the course focuses to, with particular attention to both masonry and reinforced concrete structures.

AIMS AND LEARNING OUTCOMES

At the end of the course, the student is expected:

- to be able to design/set a knowledge plan of the existing structure under examination, that is: to define the most appropriate investigation tecniques to be adotped; to define the number of test to be performed and select where carry out them; to establish the mechanical parameters to be adopted in the final assessment; to address the choices on the modelling (about both the epistemic and aleatory uncertainties)

- to be able to recognize the most relevant vulnerability factors of existing buildings, with reference to both reinforced concrete structures and masonry strucutures

- to be able to proceed with the safety verification of the existing structure, with particular reference to ordinary loads and the seismic action

TEACHING METHODS

Frontal lessons. The slides are provided before the lessons. 

Moreover, two exercises carried out in class with the supervision of the teacher are usually carried out. One addressed to have a practical example of the modelling of a simple unreinforced masonry building according to the equivalent frame apprroach, the other to apply the principles of the nonlinear kinematic analysis.

SYLLABUS/CONTENT

- Knowledge phase. Epistemic and aleatory uncertainties. Factors to be investigated (material properties, structural details, geometry, hystorical analysis). Knowledge levels and confidence factors according to national and international codes. Investigation tecniques. Sensitivity analysis.

- Basic of the performance based assessment.

- Masonry existing buildings. Verification criteria to ordinary loads. Seismic response according to the in-plane and out-of-plane response. Capacity models for assessing the in-plane response of masonry panels (strength criteria, drift limits). Nonlinear static analyses and modelling criteria (with particular reference to the equivalent frame models). Kinematic approach for assessing the out-of-plane response.

-Reinforced concrete existing buildings. Vulnerability factors to the seismic actions (irregularities, role of infills, frame designed only to gravity loads). Capacity models for existing elements (shear models, ultimate chord rotation). Performance M-N domain. Basics principles of the SLAMA method to evaluate the capacity curve.

RECOMMENDED READING/BIBLIOGRAPHY

All the text of national and international codes are provided to the students (Italian code, Eurocode 8-3, ASCE 41-13, NZSEE 2017)

Moreover, several journal papers and book chapters are provided to the students to deepend the various contents examined during the lessons. These documents are updated every year in order to be up-to-date with the most advanced scientific research.