Thread Effect on the Initial Stiffness of Bolted Connections (original) (raw)

Thread effects on the stiffness of bolted shear connections

Journal of Constructional Steel Research, 2019

This paper investigates the effects of bolt threads on the initial and final stiffnesses of double-shear bolted connections through laboratory tests and finite element (FE) analyses. Nineteen specimens composed of 4.7 mm and 8.0 mm thick structural steel plates with bolt diameters of 20 mm and 30 mm having varying end distances are studied. The investigation, which involves shank and thread bolted connections, has found that the threads reduce the initial stiffness but increase the final stiffness. The FE analysis shows that the reduction in the initial stiffness is due to the bolt threads cutting into the connected plate, increasing the initial displacement. However, the same factor moderates the softening behaviour of a thread bolted connection as it approaches its ultimate capacity. The FE simulation shows that in certain cases this newly discovered phenomenon is caused by the threads restraining the crimpling of the plate material downstream of it. The present modelling technique significantly improves the simulation results of bolted connections tested by independent researchers, compared to their own modelling techniques including that which attempts to simulate the thread effects by reducing the diameter of the bolt model. The "elastic" stiffness values obtained from the present laboratory tests are compared against the Eurocode's provision based on the ASTM definition, and ad hoc stiffness formulae are proposed for shank and thread bolted connections.

Numerical Analysis of a Double Shear Standard Bolted Connection Considering Monotonic Loadings

Engineering Structures and Technologies

The behaviour of standard bolted steel connections submitted to monotonic loads, through the use of numerical models, is presented in the current paper. The bolted connections allow speed up constructive processes in an increasingly competitive and globalized world in which the costs are a decisive factor in the development of a project. The use of computational tools in the analysis of bolted connections becomes determinant, mainly for new solutions or solutions less explored in terms of design codes. Throughout the years, bolted connections have been suffering transformations resulting from research activities performed by many authors. Rivets have been replaced by bolts, the main achievement being the pre-stressed bolts. Methodologies based on finite element analyses were proposed for double shear bolted connection. The non-linear behaviour of these connections is investigated and their performances are compared. In the numerical modelling of the bolted connection, linear elastic...

Behavior of extended end-plate bolted connections subjected to monotonic and cyclic loads

Engineering Structures, 2019

Extended end-plate bolted connections are widely used in the steel structures as moment resisting connections. Most of these connections are flexible or in other words semi-rigid. The present research aims to study the behavior of such connections under the effect of both monotonic and cyclic loadings using the Finite Element Method (FEM). For flexible connections, it is very important to obtain the moment-rotation relationship as well as the connection stiffness. This stiffness can be used to model the flexible connections in the conventional nonlinear stiffness analysis of steel frames. Parametric study was made on extended end-plate bolted beamcolumn connections subjected to both monotonic and cyclic loading to study the effect of number of parameters; shear force, diameter of bolt, thickness of head plate, and the effect of using head plate stiffener. Present parametric study shows that the value of shear force acting on the connection has a significant effect on the connection stiffness.

FINITE ELEMENT ANALYSIS OF BEAM-BEAM BOLTED CONNECTION UNDER PURE MOMENT

In structural engineering, the main purpose is to maintain structural stability against the effect of various forces acting on the structure. Also, when comparing steel and RC structures, the design of the steel structure focuses primarily on the joints. Proper and effective connections play an inevitable role in maintaining the structural stability of the steel structure. Currently, bolts are widely used fastener to connect steel connections. This project is an attempt to determine the influence of shear capacity by gauge distance on bolted connection. In order to achieve this objective, Finite Element Analysis were carried out in Ansys workbench 2021 r2. The analysis consists of 24 parametric studies that are carried out on 24 models. Each models are differ by the types of bolt hole clearance, bolt diameter, gauge distance and cleat angle used. The entire parametric study is mainly followed by using 10.9 High Yield Friction Grip (HYFG) bolt of diameter 16 mm and 20 mm.

Numerical Study on Ultimate Behaviour of Bolted End-Plate Steel Connections

Latin American Journal of Solids and Structures, 2016

Bolted end-plate steel connections have become more popular due to ease of fabrication. This paper presents a three dimension Finite Element Model (FEM), using the multipurpose software ABAQUS, to study the effect of different geometrical parameters on the ultimate behavior of the connection. The proposed model takes into account material and geometrical non-linearities, initial imperfection, contact between adjacent surfaces and the pretension force in the bolts. The Finite Element results are calibrated with published experimental results ''briefly reviewed in this paper'' and verified that the numerical model can simulate and analyze the overall and detailed behavior of different types of bolted endplate steel connections. Using verified FEM, parametric study is then carried out to study the ultimate behavior with variations in: bolt diameter, end-plate thickness, length of column stiffener, angle of rib stiffener. The results are examined with respect to the failure modes, the evolution of the resistance, the initial stiffness, and the rotation capacity. Finally, the ultimate behavior of the bolted end-plate steel connection is discussed in detail, and recommendations for the design purpose are made.

Experimental model of the behaviour of bolted angles connections with stiffeners

International Journal of Steel Structures, 2016

This paper presents the experimental results of twenty full scale specimens of steel bolted connections beam-to-column with top-and-seat angles in six groups, labelled L91-tp8, L82-tp8, L73-tp8, L91-tp10, L82-tp10 and L73-tp10 groups (L=length of top-and-seat angle, tp=stiffener thickness of top-and-seat angle), under static loading. This study was undertaken to analyse the influence of angles and beams with stiffeners on the behaviour of the beam-to-column joints. The main parameters observed are the evolution of the resistance, the stiffness, the rotation capacity, the ductility of a joint, and the energy dissipation capacity. The aim was to provide necessary data to improve the Eurocode 3.

Numerical simulation of bolted connections

Latin American Journal of Solids and Structures, 2018

This article presents the modeling of a complete bolted connection based on a model with one bolt connecting two or three plates. Initially, the behavior of this model with one bolt is analyzed by comparing it with existing bibliography for 3 different types of applied load: tension, shear and a combination of these two. This model includes all necessary considerations: contacts between the plates and the nut, head and shank of the bolt; contact between the plates, as well as friction between them; and pre-load on the bolt. The model also responds properly to loads parallel and perpendicular to the contact surface between the plates, including prying action effects. These calibrated models are then introduced as super-elements in empty spaces left on the full connection, through a relatively simple process using the finite element software ANSYS ®. Upon filling these spaces, two complete connection models are evaluated: one with a single plate and one between two Tstubs. The results obtained with these models are compared with standard forecasts. These two connection types have a practical application in the way they will be analyzed, and also as part of more complex connections: bolted girder splices (in the region of web beam), beam-to-column connections with splice plates or end plate connections, beam splices with end-plates, etc.

Analysis on Shear Behavior of High-Strength Bolts Connection

Because of high cost of tests and numerical calculation using solid element of high-strength bolts connection in steel frameworks, it is important to find an accurate and simplified approach to describe the shear behavior of high-strength bolts connection. The paper aims to find a spring element to simulate the shear behavior instead of solid element in structure. Firstly, solid element model of high-strength bolt connection is established, which is proved correct and applicable comparing with existing typical shear tests. Then, base on the reliability of finite element model, the shear behavior of bolts connection is further discussed through a large number of parameter analyses. The three feature points and four stages of the simplified shear model are calibrated according to tests and calculation results. A simplified shear behavior model and hysteretic criterion of high-strength bolts connection are proposed. According to cases study, feasibility of the proposed model is validated. The proposed model gives a simple process to provide quite accurate results, which provides a great tool for engineering applications.

Finite element investigation on the structural behaviour of cold-formed steel bolted connections

Engineering Structures, 2001

A finite element model with three-dimensional solid elements was established to investigate the bearing failure of cold-formed steel bolted connections under shear. It was demonstrated (Chung and Ip. Engineering Structures 2000;22:1271-1284) that the predicted load-extension curves of bolted connections in lap shear tests followed closely to the measured load-extension curves provided that measured steel strengths and geometrical dimensions were used in the analysis. Furthermore, it was shown (Chung and Ip.

Unitary model for the analysis of bolted connections using the finite element method

Engineering Failure Analysis, 2019

This paper presents the numerical simulation of a model with one bolt connecting two or three plates using the finite element method. This unitary model with one bolt is validated by comparing its results with those obtained in the literature for three different types of applied load: tension, shear, and a combination of both. The results are also compared with the American and Brazilian design codes. The unitary model includes all necessary considerations: contacts between the plates and the nut, head and shank of the bolt; contact between the plates, as well as the friction between them; and pre-load on the bolt. Moreover, it responds properly to forces parallel and perpendicular to the contact surface between the plates including prying action effects and slip. These calibrated models can be then introduced on a model that represents a full connection through a relatively simple process using ANSYS APDL language, thus allowing the study of any bolted connection type.