Model for predicting the Axial Strength of joints made with glued-in rods in sawn timber

Abstract Joints made with glued-in rods in sawn timber have been used for over 40 years in timber engineering, both for joint design in new constructions as well as in the repair of wood elements damaged by humidity or xylophage attack. One of the problems limiting the use of these types of joints is the absence of legislation regulating their sizing and design. Although EuroCode has given some proposals for estimating the load capacity of these joints, in practice, destructive testing must be performed for each specific case. Recent studies have offered design criteria and sizing restrictions, in most cases, for elements of glued laminated timber. Our research group has been studying the behavior of these joints in sawn timber for several years. The objective of this research is to determine the influence that different joint materials and geometric parameters have on their Axial Strength. A broad experimental study was performed on joints made with threaded steel rods glued with different types of adhesives and in different hardwood species. Over 400 specimens were tested with different geometric configurations, varying anchorage length, rod diameter and adhesive thickness. This paper presents a summary of the results obtained in the experimental analysis and proposes a model for predicting joint Strength in sawn timber. Similarly, a comparative study of our design proposal is presented with the most recent equations for glued laminated timber connections.

Model for predicting the Axial Strength of joints made with glued-in rods in sawn timber

Joints made with glued-in rods in sawn timber have been used for over 40 years in timber engineering, both for joint design in new constructions as well as in the repair of wood elements damaged by humidity or xylophage attack. One of the problems limiting the use of these types of joints is the absence of legislation regulating their sizing and design. Although EuroCode has given some proposals for estimating the load capacity of these joints, in practice, destructive testing must be performed for each specific case. Recent studies have offered design criteria and sizing restrictions, in most cases, for elements of glued laminated timber. Our research group has been studying the behavior of these joints in sawn timber for several years. The objective of this research is to determine the influence that different joint materials and geometric parameters have on their Axial Strength. A broad experimental study was performed on joints made with threaded steel rods glued with different types of adhesives and in different hardwood species. Over 400 specimens were tested with different geometric configurations, varying anchorage length, rod diameter and adhesive thickness. This paper presents a summary of the results obtained in the experimental analysis and proposes a model for predicting joint Strength in sawn timber. Similarly, a comparative study of our design proposal is presented with the most recent equations for glued laminated timber connections. © 2010 Elsevier Ltd. All rights reserved.

Ultimate Axial Strength of Concrete-Filled Double Skin Steel Tubular Column Sections

This study aims at proposing a new model for evaluating the ultimate Axial Strength of concrete-filled double skin steel tubular (CFDST) composite columns. For this, a total of 103 experimental data regarding the ultimate Strength of CFDST columns under Axial loading were collected from the previous studies in the literature. All CFDST columns consist of two steel tubes being outer and inner circular hollow section. The model presented herein was developed by using gene expression programming. For this, the yield Strength, diameter, and thickness of both outer and inner steel tubes, the compressive Strength of annulus concrete, the length of the specimen, and the ultimate Axial Strength of the columns were utilized as the parameters. Assessment of the obtained results indicated that the generated model had a good performance compared to the existing models by the previous researchers and the equations specified in the design codes. The high value of R2 and narrow ranged fluctuation of the estimation error for the ultimate Axial Strength of the CFDST columns were also achieved through the proposed model.

Comparison of ultimate Strength results from ACI and Eurocode 4 for steel tubular columns filled with SCC

The Concrete Filled Steel Tubular (CFST) columns have several benefits in comparison to the ordinary steel or reinforced concrete ones. Therefore, they have become more commonly acknowledged in the structural applications. In this study, two design codes such as American Concrete Institute (ACI) and Eurocode 4 (EC4) were used for predicting the ultimate Axial Strength of CFST columns filled with self-compacting concrete (SCC). To evaluate the results, circular steel tube with different diameter to thickness (D/t) ratio of 30, 60, and 90 and steel yielding Strength of 185, 275, and 450 MPa were considered as prediction parameters. The wall thickness and length to diameter (L/D) ratio of the steel tubes were kept constant. As an infill material for the steel tubes, 16 different SCC mixtures reported in the literature were studied and their compressive Strength results were used to get the code predicted ultimate Axial Strength of the composite columns. The analysis of the results based on ACI and EC4 were performed and discussed comparatively.

Model for predicting the Axial Strength of joints made with glued-in rods in sawn timber

Abstract Joints made with glued-in rods in sawn timber have been used for over 40 years in timber engineering, both for joint design in new constructions as well as in the repair of wood elements damaged by humidity or xylophage attack. One of the problems limiting the use of these types of joints is the absence of legislation regulating their sizing and design. Although EuroCode has given some proposals for estimating the load capacity of these joints, in practice, destructive testing must be performed for each specific case. Recent studies have offered design criteria and sizing restrictions, in most cases, for elements of glued laminated timber. Our research group has been studying the behavior of these joints in sawn timber for several years. The objective of this research is to determine the influence that different joint materials and geometric parameters have on their Axial Strength. A broad experimental study was performed on joints made with threaded steel rods glued with different types of adhesives and in different hardwood species. Over 400 specimens were tested with different geometric configurations, varying anchorage length, rod diameter and adhesive thickness. This paper presents a summary of the results obtained in the experimental analysis and proposes a model for predicting joint Strength in sawn timber. Similarly, a comparative study of our design proposal is presented with the most recent equations for glued laminated timber connections.

Influence of timber density on the Axial Strength of joints made with glued-in steel rods: An experimental approach

Abstract Joints made with glued-in steel rods have many possibilities in the design of timber structures. They can be used for new buildings or for the rehabilitation of old structural elements damaged by the attack of biotic agents or humidity. Since the 1970s many studies have been carried out to characterize the Strength of these joints when made with glued laminated timber (glulam). These studies hypothesize that the Axial Strength of joints made in glulam depends on some geometric parameters (anchorage length, steel rod diameter, adhesive thickness, etc.) as well as on timber density. For several years our research group has been studying the behavior of these joints when made in sawn timber, determining the influence of different geometric and material parameters on the Axial Strength of the glued-in steel rods. This work summarizes the experimental results of joints made in pieces of sawn timber of two species having different densities and mechanical properties. The experimental study was carried out for different geometric configurations: threaded steel rods of 10 and 12 mm diameter, epoxy adhesive of 1 mm thickness, and five anchorage lengths. The aim was to test the same specimen conditions for each timber species studied, tali and chestnut. The experimental results show that the Axial Strength of the joints does not increase linearly with timber density. This result contradicts many of the traditional design proposals suggested for joints made in glulam.

Análisis experimental de uniones con barras de acero encoladas en maderas de castaño y elondo

This article summarizes the results of an extensive experiment designed to determine the effect of geometric and mechanical parameters on the Axial Strength of the bonds formed when threaded steel bars are glued into sawn hardwood timber. The studies conducted to date on glued wood joints have focused primarily on softwood glued laminated timber or glulam. In the present study, specimens made from two hardwood species with very different physical and mechanical properties were used to evaluate the effect of wood characteristics on the Axial Strength of such bonds. Several geometries were tested by loading a total of 190 specimens to failure.

The ultimate load values found for the specimens were compared to the design values proposed in the final draft version of Eurocode 5 (prEN 1995-1-1(2001)).