Search results for " Steel"

EXPERIMENTAL INVESTIGATION ON R.C. BEAMS RETROFITTED IN FLEXURE AND SHEAR BY PRETENSIONED STEEL RIBBONS

2014

The experimental results of three and four point loading tests on reinforced concrete beams strengthened by angles and/or pre-stressed stainless steel ribbons (CAM system) are presented. The stainless steel prestressed ribbons play the role of adjunctive transversal reinforcement as well as confine the structural element. Six flexural critical beams and nine shear critical beams were tested. In the first group four beams were retrofitted with bottom stainless steel angles and transversal ribbons, with two different spacing. In the second group three specimens were retrofitted by wrapping the beam with the ribbons, while three specimens were strengthned by perforation of the beam beneath the…

Simplified equivalent finite element modelling of concrete-filled steel tubular K-joints with and without studs

2022

Concrete Filled Steel Tubular (CFST) K-joints employed for truss structures gained high interest in the last years due to their widespread use in engineering practice. The overall performances of these joints can be efficiently improved by using steel studs welded in the inner surface of the steel chord filled with the concrete, avoiding punching shear failure, and improving the overall strength and ductility. However, a reliable prediction of the structural behavior of the joints is outmost of importance for the assessment of the capacity of new and existing structures, and there are no standardized design methods nowadays. In this paper, the structural performances of CFST K-joints with a…

FE modeling of Partially Steel-Jacketed (PSJ) RC columns using CDP model

2018

This paper deepens the finite element modeling (FEM) method to reproduce the compressive behavior of partially steel-jacketed (PSJ) RC columns by means of the Concrete Damaged Plasticity (CDP) Model available in ABAQUS software. Although the efficiency of the CDP model is widely proven for reinforced concrete columns at low confining pressure, when the confinement level becomes high the standard plasticity parameters may not be suitable to obtain reliable results. This paper deals with these limitations and presents an analytically based strategy to fix the parameters of the Concrete Damaged Plasticity (CDP) model. Focusing on a realistic prediction of load-bearing capacity of PSJ RC column…

Steel jacketing of RC columns: Reliability of capacity laws for concrete

2016

In the seismic assessment of framed R.C. structures reinforced by steel angles and battens (steel jacketing) the use of proper confinement models for concrete is still a main topic. Really, the capacity of reinforced concrete columns under concentric and eccentric loads strongly depends on confinement exerted by the external reinforcement. Further a proper attribution of concrete stress-strain laws allows obtaining reliable estimations of inelastic capacity of reinforced elements. Moreover the presence (or not) of connections of the angles with the end joints influences their capacity to support vertical loads. In the two cases the mechanical models have to account for buckling or frictiona…

Modelling steel jacketed RC columns: Remarks by experimental-numerical comparisons

2015

The recent large use of nonlinear seismic assessment techniques requires the definition of highly reliable computational models. The retrofitting or strengthening of RC columns by steel angles and battens is a commonly adopted technique, used to improve strength and deformation capacity of existing RC buildings. In the case of steel angles not directly loaded, the numerical definition of the cross-section model has to be handled carefully since it is affected by more uncertainties. The vertical load carried by the angles is a function of the lateral confinement pressure, the cohesion and the friction coefficient between the materials, parameters which are not always easy to predict. The pap…

Seismic response of RC frames with HSTC beams endowed with friction damper devices

2019

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…

Design of friction connections in R.C. structures with hybrid steel-trussed concrete beams

2019

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…

Seismic behaviour of hybrid steel trussed concrete beams

2010

On bottom steel plate to concrete anchorage in hybrid steel trussed concrete beams

2012

A semi-precast hybrid steel trussed-concrete beam typology is considered. Beams are made up of a steel truss encased in a concrete beam. The steel to concrete stress transferring mechanism is analyzed by experimental tests on six specimens of the beam. Four point bending tests on three slab thick beams and three full thick beams have been carried out. The instrumentation allowed to measure global and local response. The global response was monitored in terms of load vs. midspan-deflection curves and the local response was recorded by strain-gauges placed both on the bottom steel plate and at the top concrete surface of the beam in order to investigate the stress transfer mechanism between s…

Friction-based beam-to-column connection for low-damage RC frames with hybrid trussed beams

2022

Hybrid Steel-Trussed Concrete Beam (HSTCB) is structural typology suitable for light industrialization. HSTCBs usually cover long span with small depths, which lead to significant amount of longitudinal rebars. The latter make beam-column joints more prone to damage due to earthquake-induced cyclic actions. This phenomenon can be avoided using friction-based BCCs. Friction devices at Beam-to-Column Connections (BCCs) have become promising solutions to reduce the damage experienced by structural members during severe earthquakes. Few solutions have been developed for cast-in-place Reinforced Concrete (RC) and steel-concrete composite Moment Resisting Frames (MRFs), because of the difficulty …