Comportamiento de conectores de cortante tipo tornillo de resistencia grado dos para un sistema de sección compuesta

En Colombia, desde hace muchos años, uno de los tipos de conectores de cortante más usados son los tornillos, pero en la actualidad no existe ninguna metodología de diseño que justifique su uso en elementos de sección com-puesta, y la normatividad vigente indica que hay que realizar ensayos de los elementos que se pretendan emplear como conectores. Junto con los habituales detalles para diseño a flexión, y cortante vertical, es necesario especificar el diseño para el cortante horizontal generado en la interfase de la sección compuesta, y más aún, ajustar el diseño para las condiciones locales de construcción colombiana. Con esta finalidad se desarrolló un estudio en el cual se analizan los diversos efectos producidos en las secciones compuestas cuando se emplean tornillos como conectores de cortante. En esta investigación se estudiaron 18 modelos de sección compuesta fabricadas con perfiles de alma llena y losas de concreto de 21 MPa, en las cuales se manejaron configuraciones de 1, 2 ó 3 conectores de cortan-te tipo tornillo con diámetros de 1/2”, 5/8” ó 3/4"; y para separaciones de 0.08 m, 0.12 m o 0.14 m, por cada modelo se ensayaron tres probetas ante solicitación de corte directo (push-out). De acuerdo con los resultados obte-nidos en laboratorio, se efectuó el análisis correspondiente, evaluando la incidencia del diámetro y la separación de los conectores, en el comportamiento de los modelos, para posteriormente plantear una formulación de su dise-ño en secciones compuestas. Paralelamente, se analiza un modelo de los ensayados por medio de un programa que emplea el método de los elementos finitos, con el cual se pretende revisar en detalle aspectos poco apreciables en los ensayos físicos, entre ellos la degradación del concreto en la interfaz de la sección.Screw shear connectors have been most commonly used in Colombia for many years; however, there is no current design methodology justifying its use in composite sections and prevailing rules insist that elements used as shear connectors must be tested. Along with the usual details of bending design and vertical shear, horizontal shear design on the composite section interface must be specified, even more so in adjusting such design to Colombian construc-tion. A study was thus undertaken analysing effects on composite sections when screws were used as shear connec-tors. This research studied 18 composite section models having two 21MPa concrete slabs which had different confi-gurations with one, two or three 1/2", 5/8" or 3/4" diameter shear connector type screws, and 0.08m, 0.12m or 0.14m separations. Three specimens were tested for each model by direct shear or push-out method. The corres-ponding analysis was done according to laboratory results, assessing the influence of diameter and connector sepa-ration on the model’s behaviour; screw design in composite sections was then formulated. A model of the tests was analysed using a finite element method based-programme which reviewed in detail those aspects which had little a-ppreciable effect on the physical tests, including concrete degradation in the interface section

Grade-two resistance screw shear connector behaviour for a composite section system

Screw shear connectors have been most commonly used in Colombia for many years; however, there is no current design methodology justifying its use in composite sections and prevailing rules insist that elements used as shear connectors must be tested. Along with the usual details of bending design and vertical shear, horizontal shear design on the composite section interface must be specified, even more so in adjusting such design to Colombian construc-tion. A study was thus undertaken analysing effects on composite sections when screws were used as shear connec-tors. This research studied 18 composite section models having two 21MPa concrete slabs which had different confi-gurations with one, two or three 1/2", 5/8" or 3/4" diameter shear connector type screws, and 0.08m, 0.12m or 0.14m separations. Three specimens were tested for each model by direct shear or push-out method. The corres-ponding analysis was done according to laboratory results, assessing the influence of diameter and connector sepa-ration on the model’s behaviour; screw design in composite sections was then formulated. A model of the tests was analysed using a finite element method based-programme which reviewed in detail those aspects which had little a-ppreciable effect on the physical tests, including concrete degradation in the interface section