The use of flat-slabs as building floor solution is quite common all around the world. In recent years, the increase of use of flat slab floor systems in moderate to high seismic zones in Europe has aroused the concern of many researchers because the behavior of such structures under seismic actions is not completely understood. Although this type of floor system has certain advantages over other floor systems, flat slab structure are susceptible to suffer a punching shear failure when a correct design is not performed. The aim of this dissertation is to study the punching shear behavior of reinforce concrete flat slab structures without punching shear reinforcement under vertical and lateral loads. A total of three different structures with lateral-force resisting systems (shear walls) are analyzed and designed to evaluate the impact of punching shear in the structural design. These structures are intended to represent a typical residential building. The three structures proposed are analyzed using the Finite Element Method (FEM) through the software Midas Gen 2020 (v2.3). The design of the structures is carried out considering the provisions given by Eurocode 2 and Eurocode 8. Flat-slabs and columns are designed as secondary seismic elements. An experimental study is considered to calibrate the FEM models. The aforementioned experimental study was carried out by Coronelli et al. at ELSA laboratory of the European Commission’s Joint Research Centre. The specimen studied was a full-scale two-story flat-slab structure subjected to vertical and lateral loads. The models proposed to analyze the structures showed a good correspondence between the numerical and the experimental global structural behavior. Experimental results of the performance of the slab-column connections are compered with the numerical results obtained for the different structures presented. The results obtained showed the importance of the correct modelling of flat-slab structures under lateral loading. A stiffness reduction factor for bending of 0.25 is suggested for slabs when a flat-slab structure is linearly analyzed inside FEM software. Additionally, when designing this type of structures, a Gravity Shear Ratio (GSR) between 0.3 an 0.4 is suggested. The use of large spans is not recommended when the structure is subjected to lateral loads and lateral-force resisting systems should be present.
L'uso di piastre in calcestruzzo armato senza travi come soluzione dei solai degli edifici è abbastanza comune in tutto il mondo. Negli ultimi anni, l'aumento dell'uso di questo sistema di solai in zone di intensità simica da moderata ad alta in Europa ha suscitato preoccupazione in molti ricercatori perché il comportamento di tali strutture durante le azioni sismiche non è completamente compreso. Sebbene questo tipo di sistema a piastra presenti alcuni vantaggi rispetto ad altri sistemi, è suscettibile di subire punzonamento quando non viene eseguita una progettazione strutturale corretta. Lo scopo di questa tesi è di studiare il comportamento a punzonamento a taglio di strutture a piastra senza travi in calcestruzzo armato senza armatura trasversale sotto carichi verticali e laterali. Un totale di tre diverse strutture con sistemi di resistenza alle forze laterali (pareti di taglio) vengono analizzate e progettate per valutare l'impatto del punzonamento nella progettazione strutturale. Queste strutture intendono rappresentare un tipico edificio residenziale. Le tre strutture proposte vengono analizzate utilizzando il Metodo degli Elementi Finiti (FEM) tramite il software Midas Gen 2020 (v2.3). La progettazione delle strutture viene effettuata tenendo conto delle disposizioni dell'Eurocode 2 e dell'Eurocode 8. Il sistema a piastra e le colonne sono progettati come elementi sismici secondari. Uno studio sperimentale è considerato per calibrare i modelli FEM. Il suddetto studio sperimentale è stato condotto da Coronelli et al. presso il laboratorio ELSA del European Commission’s Joint Research Centre. L'esemplare studiato era una struttura full-scale con sistema a piastra senza travi a due piani soggetta a carichi verticali e laterali. I modelli proposti per l'analisi delle strutture hanno mostrato una buona corrispondenza tra il comportamento strutturale globale del modello numerico e quello sperimentale. I risultati sperimentali delle prestazioni di connessioni piastra colonna sono confrontati con i risultati numerici ottenuti per le diverse strutture presentate. I risultati ottenuti hanno mostrato l'importanza della corretta modellazione delle strutture a soletta piana sotto carico laterale. Un fattore di riduzione della rigidità per flessione di 0. 25 è suggerito per le piastra quando la struttura viene analizzata linearmente all'interno del software FEM. Inoltre, quando si progetta questo tipo di strutture, si suggerisce un rapporto di taglio gravitazionale (GSR) compreso tra 0.3 e 0.4. L'uso di grandi luci non è raccomandato quando la struttura è soggetta a carichi laterali e sempre all'interno della struttura devono essere presenti sistemi resistenti alle forze laterali.
Analysis and design of R/C flat-slab structures subjected to gravity and lateral loads
Mohedano Millan, Luis Felipe
2020/2021
Abstract
The use of flat-slabs as building floor solution is quite common all around the world. In recent years, the increase of use of flat slab floor systems in moderate to high seismic zones in Europe has aroused the concern of many researchers because the behavior of such structures under seismic actions is not completely understood. Although this type of floor system has certain advantages over other floor systems, flat slab structure are susceptible to suffer a punching shear failure when a correct design is not performed. The aim of this dissertation is to study the punching shear behavior of reinforce concrete flat slab structures without punching shear reinforcement under vertical and lateral loads. A total of three different structures with lateral-force resisting systems (shear walls) are analyzed and designed to evaluate the impact of punching shear in the structural design. These structures are intended to represent a typical residential building. The three structures proposed are analyzed using the Finite Element Method (FEM) through the software Midas Gen 2020 (v2.3). The design of the structures is carried out considering the provisions given by Eurocode 2 and Eurocode 8. Flat-slabs and columns are designed as secondary seismic elements. An experimental study is considered to calibrate the FEM models. The aforementioned experimental study was carried out by Coronelli et al. at ELSA laboratory of the European Commission’s Joint Research Centre. The specimen studied was a full-scale two-story flat-slab structure subjected to vertical and lateral loads. The models proposed to analyze the structures showed a good correspondence between the numerical and the experimental global structural behavior. Experimental results of the performance of the slab-column connections are compered with the numerical results obtained for the different structures presented. The results obtained showed the importance of the correct modelling of flat-slab structures under lateral loading. A stiffness reduction factor for bending of 0.25 is suggested for slabs when a flat-slab structure is linearly analyzed inside FEM software. Additionally, when designing this type of structures, a Gravity Shear Ratio (GSR) between 0.3 an 0.4 is suggested. The use of large spans is not recommended when the structure is subjected to lateral loads and lateral-force resisting systems should be present.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/189121