1,721,322 research outputs found
Oltre il regolo Da Dostoevskij a Gadda: percorsi umani e intellettuali di ingegneri-artisti
No full textA general numerical model for simulating the long-term response of two-layer composite systems in partial interaction
No full textTwo-layer composite members are widely employed in structural engineering: composite beams coupling a concrete slab to either a steel joist or a timber beam are probably the most remarkable examples of the aforementioned systems, but also other structural members can somehow be mechanically regarded as two-layer composite systems. Therefore, simulating the long-term behaviour of the aforementioned two-layer composite systems in partial interaction is a relevant and challenging problem, as it depends on both the different long-term response of the two coupled layers and the possible time-dependent behaviour of the interface. In fact, phenomena like creep and shrinkage affect materials in different ways and, hence, a general approach is needed to encompass both the particular kinematic constraints characterising two-layer composite systems in partial interaction and the peculiar behaviour of their materials. The present paper proposes a theoretical formulation and the corresponding numerical implementation of a mechanical model capable of simulating the long-term response of two-layer composite system in partial interaction. A validation of the model is proposed at the end of the paper with respect to experimental results obtained on two different two-layer composite systems reported in the literature. The Python code implemented as part of the present study is available in Open Access to readers
Analisi lineare e non-lineare di strutture composte acciaio-calcestruzzo a parziale interazione
No full textTesi di Dottorato in "Ingegneria delle Strutture" Università di Salerno I Ciclo – Nuova serie 1999-2002
Seismic Capacity Design of RC frames and environment-induced degradation of materials: Any concern?
No full textThe Capacity Design approach emerged in the second half of the last century and is currently adopted by all the modern codes of practice for construction in seismic areas. It is based on the fundamental concept that the structure under consideration should not exhibit brittle failure modes, as brittle members or mechanisms are designed to be stronger than the maximum expected stresses they possibly get from the adjacent ductile members or mechanisms. This condition is generally imposed at the design stage without considering any degradation in material properties possibly due to the environmental agents. Although structural codes for RC structures usually provide practitioners with sound criteria intended at limiting the development of detrimental degradation phenomena, they have been never assessed against the possible loss in over-strength of brittle failure modes due to environment-induced degradation phenomena possibly occurring during the service life of the structure.This study aims to answer the question stated in the title and, in the authors' knowledge, is one of the first attempts to embrace two traditionally distant research fields, such as Earthquake Engineering and Material Science. Thus, the paper investigates the time evolution of the possible failure modes in beams due to the premature degradation of steel stirrups and longitudinal reinforcement during the service life of RC structures. Both material properties and environmental conditions are taken into account to assess durability and structural safety in seismically designed RC beams and the possible consequences of material degradation on their expected failure modes under seismic actions
A novel numerical approach for modelling the monotonic and cyclic response of FRP strips glued to concrete
No full textThe mechanical behaviour of the adhesive interface between the FRP strips and the concrete substrate often controls the response of FRP-strengthened RC members. Plenty of studies devoted to understanding the mechanical behaviour of FRP strips glued to concrete mainly focused on their response under monotonic actions, which are certainly relevant in a wide class of practical applications. On the contrary, few contributions are currently available to better understand the response of FRP-to-concrete interfaces under cyclic actions, such as those deriving by either seismic excitations or traffic loads. This paper presents a novel numerical approach to simulate such a response. Particularly, a damage-based approach is formulated to simulate the fracture behaviour of FRP-to-concrete joints under loading/unloading cycling tests. The model is formulated within the general framework of Fracture Mechanics and is based on assuming that fracture at the FRP-to-concrete interface develops in (pure shear) mode II, as widely accepted in similar problems. Two alternative expressions of the bod-slip behaviour are considered herein and a preliminary validation is finally proposed
Advances in Civil and Infrastructure Engineering II
No full textAfter the successful conference of Changsha (China) in 2012, the 2nd International Symposium on Advances in Civil and Infrastructure Engineering (ACE) was held in Vietri sul Mare, Italy, in June 2015. ACE 2015, an official conference of the International Association for Innovation in Structural Engineering (iStruct), aims at providing an international forum where researchers and practitioners can be updated on the most recent advances in the field of civil engineering, with special reference to innovation in materials, concepts and new trends in modeling, design, construction and monitoring of structures. This book collects the proceedings of the works presented during the ACE 2015 Conference.
Hybrid structures; Construction monitoring; Experimental techniques; High-performance materials; Structural identification; Damage detection; Earthquake Engineering; Structural rehabilitatio
Fracture-based model for mixed mode cracking of FRP strips glued on concrete
No full textThe present work proposes a fracture-based model for analysing the cracking processes which generally characterise the behaviour of FRP strips glued to brittle materials. The proposed model aims at simulating the mixed mode of such cracking processes actually characterised by a 2D displacement field. This aspect is usually neglected in the most common proposals available in the scientific literature, as theoretical models are generally based on assuming the simplified hypothesis of pure “mode II” response. The proposed model is based on four-node plane stress elastic elements generally simulating the two adherents, connected to each other through a layer of zero-thickness interface elements. A hyperbolic maximum strength criterion in the normal/shear stress space is considered for such interfaces and post-peak behaviour is controlled by the fracture work spent under I and/or II failure modes. Finally, numerical simulations of pull-out tests are presented with the aim of emphasising the predictive capabilities of the proposed formulation
Dostoevskij, Gadda ed altri ingegneri-artisti: giornata di studio della Facoltà di Ingegneria di Salerno
No full textFracture-based interface formulation for FRP-to-concrete debonding mechanisms in mixed cracking mode
No full textThe present work proposes a fracture-based model for analysing the cracking processes possibly arising at the interface between FRP strips loaded in tension and glued to concrete or other brittle substrates. Particularly, it aims at simulating the “mixed” nature of such cracking processes actually characterised by both axial and transverse relative displacement components. The model is formulated within the general framework of the Finite Element Method. Thus, four-node plane stress elastic elements simulate the two adherents, which are connected to each other via a layer of zero-thickness interface elements where all mechanical nonlinearities, induced by the cracking process, are actually embedded. A hyperbolic maximum strength criterion, in the normal/shear stress space, is considered for such interface elements and post-peak behaviour is controlled by the fracture work spent under I, II and/or mixed failure modes. Finally, numerical simulations of pull-out tests are presented to highlight the predictive capabilities of the proposed formulation
- …
