Search results for "concrete"
showing 10 items of 262 documents
Ductility of Reinforced Concrete Members Externally Wrapped with Fiber-Reinforced Polymer Sheets
2007
The effectiveness of external wrapping with fiber-reinforced polymer for enhancing the curvature ductility of lightly reinforced concrete members is investigated. Referring to members with circular transverse cross sections, the performances in terms of both strength and ductility capacities are analyzed, and the predictive reliability of two different recent constitutive models, available in the literature and able to take into account the softening behavior of confined concrete, is checked. A parameter characterizing the effectiveness of the confining wrapping is proposed, and characteristic values are suggested. Moreover, referring to ductility increases due to confinement effects, a com…
Seismic behavior of exterior RC beam-column joints without code-specified ties in the joint core
2021
Abstract Beam-column joint design for reinforced concrete (RC) buildings is a critical issue for modern earthquake engineering, because for these structural elements, the current codes provide several geometrical constraints and reinforcement provisions, which may be very complex to implement during the construction phase. To investigate how a construction error might influence the joint behavior, two identical full-scale exterior beam-column joints specimens are built, according to Italian Building Code specifications for the high ductility class, but without the required horizontal ties inside the joint panel. This construction error could be plausible because, according to the design dra…
Mechanical Tests on Innovative BIPV Façade Components for Energy, Seismic, and Aesthetic Renovation of High-Rise Buildings
2018
The paper shows the results of mechanical tests carried out on prototypes of a new Building Integrated Photovoltaic (BIPV) component developed by the author and SBskin Smart Building Skin s.r.l. This patented innovative component is able to merge structural function, insulation proprieties, and production of clean energy for retrofit actions and/or the construction of translucent faç
Bending-Shear interaction domains for externally prestressed concrete girders
2013
In prestressed concrete structures, the evaluation of the safety level is generally carried out by separating the bending moment strength and the shear force capacity. Actually interaction between bending moment (M) and shear force (V) can have significant consequences on evaluations in service life, especially when the ultimate limit state (ULS) is considered. In this paper, the M-V interaction is addressed for prestressed concrete girders, in the cases of both bonded and unbonded prestressing tendons. It can be demonstrated, by drawing the interaction domains (M-V), that a significant reduction of the safety level has to be considered when shear force is evaluated together with bending mo…
Increasing the Capacity of Existing Bridges by Using Unbonded Prestressing Technology: A Case Study
2014
External posttensioning or unbonded prestressing was found to be a powerful tool for retrofitting and for increasing the life extension of existing structures. Since the 1950s, this technique of reinforcement was applied with success to bridge structures in many countries, and was found to provide an efficient and economic solution for a wide range of bridge types and conditions. Unbonded prestressing is defined as a system in which the post-tensioning tendons or bars are located outside the concrete cross-section and the prestressing forces are transmitted to the girder through the end anchorages, deviators, or saddles. In response to the demand for a faster and more efficient transportati…
Conceptual design of prestressed slab bridges through one-way flexural load balancing
2013
In this paper a study on prestressed concrete slab bridges is presented. A design philosophy based on the concept of load balancing through prestressing is proposed in order to minimize the effects of delayed deformations due to creep. Aspects related to the stress redistribution inside these bridges for time-dependent phenomena are analyzed and discussed, by applying the principles of aging linear visco-elasticity. Prestressing is seen as an equivalent external load which counterbalances the permanent loads applied to the bridge, nullifying the elastic deflections due to sustained loads, and thus avoiding the related delayed deformations. An optimization of the structural behavior through …
Load carrying capacity of RC compressed columns strengthened with steel angles and strips
2012
Abstract In this paper a comparison between the analytical expressions for the prediction of the load carrying capacity of strengthened reinforced concrete (RC) columns with steel angles and strips is made. Expressions examined consider: the strength contribution due to the confinement effects induced by transverse strips; the composite action due to steel angles and unconfined concrete core; the strength contribution due to the composite actions of angles and concrete core taking into account that steel angles are subjected to axial force and bending moment and concrete core is confined by transverse strips. Design rules given by recent codes for the design of the strengthened columns are …
Review of push-out and shear response of hybrid steel-trussed concrete beams
2018
The hybrid steel trussed concrete beams examined in the present study are comprised of two principal components, i.e., a steel joist with inclined rebars, realized in industry, which is welded to a smooth steel plate and then embedded within the concrete cast in situ. The paper presents first the state of the art on laboratory tests and analytical modeling of the steel-to-concrete stress transfer mechanism investigated by push-out tests. Next, the most relevant scientific contributions currently available in the technical literature regarding experimental investigation on actual shear behavior are summarized and discussed. Lastly codes and analytical models are reviewed.
Validation of a Shear Model for RC and Hybrid Beams with Two Different Inclinations of Transversal Reinforcement
2016
The validation of an analytical model recently proposed for evaluation of the shear capacity in Reinforced Concrete (RC) beams containing multiple inclination of transverse stirrups is presented. The model is a suitable extension of that currently proposed in Eurocode 2 for the evaluation of the shear resistance, and it is derived by means of the the variable-inclination stress-field theory based on Nielsen’s plastic approach. Experimental and numerical data available in the literature on Hybrid Steel-Trussed Concrete Beams (HSTCBs) are used for model validation and result discussion. Finally, also the comparison with a different analytical approach for the assessment of the shear resistanc…
Analytical evaluation of steel–concrete composite trussed beam shear capacity
2015
A calculation method for the prediction of the shear resistance of precast composite beams, named Hybrid Steel Trussed-Concrete Beams (HSTCBs), is herein proposed. HSTCBs are constituted by a prefabricated steel truss embedded within a concrete matrix cast in situ so that, after curing, the two materials work together in the mechanical response of the composite structural element, the steel truss behaving as reinforcement of the beam. The proposed analytical model is developed on the basis of the results of a reference experimental campaign of three-point bending tests available in the literature, carried out on specimens of HSTCB designed in order to attain a shear failure. Furthermore, th…