R/C flat slab connections under lateral loading,
Lapi, Massimo, Isufi Brisid, Orlando Maurizio, and Ramos António
, XVII Convegno ANIDIS – L´Ingegneria Sismica in Italia, Pistoia, Italy, p.8 pp-, (2017)
A hybrid method for the calibration of finite element models of punching-shear in R/C flat slabs,
Lapi, Massimo, Secci Lorenzo, Teoni Emanuele, Ramos Antonio Pinho, and Orlando Maurizio
, Computers & Structures, Volume 238, p.106323, (2020)
AbstractThe paper is focused on the calibration of non-linear 3D finite element (FE) analyses to simulate punching failure of R/C flat slabs. The calibration procedure is developed with reference to the code ABAQUS, which is one of the most used computer codes in nonlinear modelling of R/C structures. Generally, the calibration of a nonlinear FE model is grounded on one test only, so its reliability could be limited. Here a hybrid method for the calibration of FE models of R/C flat slabs failing in punching is proposed and discussed. The method consists in calibrating input data by comparison of finite element model (FEM) results with both experimental data and predictions provided by analytical models. The procedure allows for a consistent calibration to be performed, valid for a wide range of longitudinal reinforcement ratios, from 0.5% to 2.00%, and concrete grades, from C20/25 to C50/60. A case study is investigated using the proposed method. Results show that calibrated values of the fracture energy lie between those provided by Model Code 1990 and Model Code 2010. From the new calibration procedure, a relationship between fracture energy and concrete compressive strength is also derived and blind analyses are performed to check its reliability against experimental results.
Performance assessment of flat slabs strengthened with a bonded reinforced-concrete overlay,
Lapi, M., Fernandes H., Orlando M., a Ramos, and Lúcio V.
, Magazine of Concrete Research, Volume 70, Number 9, p.433-451, (2018)
Abstractn/a
Comparison of flat slab strengthening techniques against punching-shear,
Lapi, Massimo, Martini Daniele, Zagli Emilio, Orlando Maurizio, Ramos Antonio, and Spinelli Paolo
, Proceedings of The New Boundaries of Structural Concrete 2016, NBSC2016, Italy ACI Chapter, Capri, Italy, (2016)
AbstractPunching-shear capacity of slab-column connections in existing R/C structures may be inadequate to bear design loads, so strengthening works are required. The lack of punching resistance may be due to detailing, design or building errors; in other cases, such lack is due to a change of use, which requires an increase of resistance. Different techniques have been developed for strengthening R/C slabs against punching: enlargement of the support, gluing external fibre reinforced polymers or casting a bonded concrete overlay (BCO) on the slab's top surface, insertion of post-installed steel bolts, application of fibre reinforced polymers cords as shear reinforcement. In the paper, the authors apply the Critical Shear Crack Theory (CSCT) to all of these techniques and evaluate their efficacy with reference to a case study.
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