0000000000370586
AUTHOR
P. Colajanni
Dissipative connections of rc frames with prefabricated steel-trussed-concrete beams
In the last thirty years, Hybrid Steel-Trussed Concrete Beams (HSTCBs) have been widely used in civil and industrial constructions and, therefore, their mechanical performance must be evaluated with the aim of guaranteeing adequate dissipation of the seismic energy particularly in the beam-to-column joints. However, one of the most frequent peculiarities of HSTCBs is that of using their own steel joist to cover large spans with reduced depth and, in the case of traditional beam-to-column connections, this requires large amount of steel reinforcement inside the panel zone, often made with large diameter rebars. These characteristics make both the panel zone and the beam end potentially vulne…
Comparison of approaches for generation of fully non-stationary artificial accelerograms
The modelling of the seismic input is a critical aspect when non-linear time-history analyses (NLTHAs) are carried out. As a matter of fact, seismic response of structures is very sensitive to the input excitation time history. The present work aims to highlight the differences in the input modelling and the assessment of seismic response of three r.c. structures employing four generation methods of fully non-stationary artificial accelerogram sets at a given construction site. For each method, seven accelerograms are generated and employed to perform NLTHAs on three r.c. structures having irregular mass and stiffness distributions. The original contribution of the paper relies in the crite…
Combination coefficients for modal pushover analysis
Conventional non-linear static analysis estimates the response peak value by evaluating the pushover curve adopting a distribution of invariant forces proportional to the fundamental vibration mode. In order to include the effect of higher modes, multi-modal push-over analysis has been proposed in literature. Nodal response peak values are obtained by combination of “modal” responses usually by the traditional CQC method, requiring cross correlation coefficients defined for linear systems. In this paper, the accuracy of correlation coefficients for linear systems in predicting the statistical correlation of hysteretic oscillator responses is investigated by the Monte Carlo Simulation conduc…
Seismic response of RC frames with HSTC beams endowed with friction damper devices
The aim of this work is to compare the seismic response of RC frames built using Hybrid Steel-Trussed Concrete Beams (HSTCBs) whether or not equipped with friction damper devices installed at the beam-to-column joints. Due to their small depth-to-span ratios, HSTCBs usually lead to a large amount of rebar within the beam-column joint, potentially reducing its cyclic performance. Therefore, the adoption of a friction system at the beam-tocolumn joint provides two main advantages, i.e. limiting the shear forces, and thus the potential damage, in the panel zone thanks to the increasing of the bending moment lever arm, and assigning to the device the task of dissipating the incoming seismic ene…
Experimental results of RC columns strengthnened with Fiber Reinforced Cementitious Mortars
The structural behaviour of reinforced concrete columns strengthened with a system made up of fibre nets embedded in an inorganic stabilized cementitious matrix was investigated. Specimens with circular and square cross-section were cast and subjected to monotonic uniaxial compression to investigate the efficiency of a Polypara-phenylene-benzo-bisthiazole (PBO) Fibre Reinforced Cementitious Mortars (FRCM) system in increasing both carrying capacity and ductility. The experimental results show that confinement with PBO fibre produced a noticeable increment in strength and ductility, though the low mechanical ratios of fibre considered were not always able to ensure hardening behaviour up to …
Shear models of Rc-encased steel joist beams in MRFs
This study presents the application of different analytical and finite element (FE) models aimed at predicting the shear resistance of reinforced concrete (RC) and reinforced concrete-encased steel joist (HRCESJ) beams with inclined transversal reinforcement in moment resisting frames (MRFs). In particular, four analytical models are taken into account, two of them specifically conceived for HRCESJ beams in seismic area. The analytical models considered are Eurocode-2 model for the shear strength of RC beams; a variable-inclination stress-field approach; a strut-and-tie additive model and, finally, an analytical formulation in which the shear capacity depends on the number of pairs of incli…
Design of friction connections in R.C. structures with hybrid steel-trussed concrete beams
In this work a feasibility study on the use of friction devices within beam-to-column joints of RC structures is conducted. The connection is made between RC columns cast in-situ and semi-prefabricated steel-concrete beams, named Hybrid Steel-Trussed-Concrete Beams (HSTCBs). Nowadays, HSTCBs are widely adopted in civil and industrial buildings and, therefore, it is required to evaluate their compliance with the capacity design criteria and their seismic energy dissipation capability. However, the design of the reinforcement of such beams usually lead to the adoption of large amount of steel within the panel zone which becomes potentially vulnerable to the effects of seismic cyclic actions a…
Flexural behavior of corroded RC beams
Synopsis: A handily model to evaluate the bending resistance and the ductility of corroded beams critical in flexure and shear is proposed and debated. Effects of diffused and pitting corrosion on steel bars, compressive concrete strength reduction and concrete bond strength reduction due to rust creation are modelled. Practical method derived on limit state theory was here used to calculate the flexural and shear strength and the available ductility. The effectiveness of the model was also corroborated against numerous results collected in the literature pertaining to bending and shear resistance.
6th Workshop on The New Boundaries of Structural Concrete 2022 University of Salento – ACI Italy Chapter
Geopolymer cement is a viable alternative to ordinary cement in order to significantly reduce the emission of carbon dioxide related to the construction of concrete structures. Being made up of waste materials, geopolymer cement also helps to limit the use of new raw materials, leading to a considerable reduction of the environmental impact of the construction industry. During the last years, the use of Geopolymer Recycled Aggregate Concrete (GRAC) in structural members has been studied in several recent experimental research in which the behavior of either the material or structural member was investigated. A review paper will be done critically to compile the present research on the use o…
Tecniche di analisi statica non lineare multimodale per strutture intelaiate
Viene presentata una panoramica delle più efficienti tecniche di analisi statica non lineare, evidenziando i progressi fatti nella formulazione di procedure con profili di carico adattivi multimodali, finalizzati alla valutazione della risposta di strutture a comportamento fortemente non lineare. Vengono poi presentate le diverse procedure che consentono di analizzare il comportamento di strutture irregolari in altezza o con grandi periodi di vibrare, nella quale la risposta è fortemente influenzata dai modi superiori. In quest’ambito viene evidenziato il ruolo della procedura Modal Pushover Analysis, che risulta fra le più efficienti nel riprodurre il comportamento di strutture fortemente …
SHEAR RESISTANCE OF R/C BEAMS PROVIDED WITH DIFFERENTLY-INCLINED TRANSVERSE REINFORCEMENT
The model for the evaluation of shear resistance of reinforced concrete member provided with transverse web reinforcement, derived by Nielsen (1999) on the basis of the variable inclination stress field approach, is generalized here to predict the shear strength of r.c. beams equipped with two sets of differently-inclined transversal web reinforcement and longitudinal skin reinforcement. Numerical analyses emphasize the efficiency of double inclined web transverse reinforcement in providing shear strength to beams.
Influence Of Lateral Load Distributions On Pushover Analysis Effectiveness
The effectiveness of two simple load distributions for pushover analysis recently proposed by the authors is investigated through a comparative study, involving static and dynamic analyses of seismic response of eccentrically braced frames. It is shown that in the upper floors only multimodal pushover procedures provide results close to the dynamic profile, while the proposed load patterns are always conservative in the lower floors. They over-estimate the seismic response less than the uniform distribution, representing a reliable alternative to the uniform or more sophisticated adaptive procedures proposed by seismic codes. © 2008 American Institute of Physics.
Simplified Formulation of Solution for Beams on Winkler Foundation allowing Discontinuities due to Loads and Constraints
The paper discusses material for a course in Structural Mechanics addressed to second-Year Civil Engineering students. The response of beams on a Winkler foundation characterized by discontinuities in both the displacements (deflections and/or slopes) and forces (internal forces and/or loads) is studied. In particular, a simplified formulation for the solution of the discontinuous differential equation governing this problem is given. In some cases, the formulation is able to give the exact solution in a closed form. This is made possible through the use of the generalized functions, such as the well-known Unit Step Function and the Dirac delta function. The cases of discontinuities due to …