Effects of the Rate of Cyclic Loading on the Load-carrying Capacity and Inelastic Behavior of Reinforced Concrete Columns

Effects of the Rate of Cyclic Loading on the Load-carrying Capacity and Inelastic Behavior of Reinforced Concrete Columns
Author: Takeshi Arakawa
Publisher:
Total Pages: 8
Release: 1982
Genre: Columns, Concrete
ISBN:

The purpose of this investigation was to study the effect of loading rate on the strength and ductility of concrete columns subjected to a combination of shear and flexural moment with axial force. Particular emphasis is given to the comparison of the performance of the specimens in this test with the evaluated results of deformation capacity previously proposed.

Seismic Assessment and Retrofit of Reinforced Concrete Columns

Seismic Assessment and Retrofit of Reinforced Concrete Columns
Author: Konstantinos G. Megalooikonomou
Publisher: Cambridge Scholars Publishing
Total Pages: 387
Release: 2019-02-27
Genre: Technology & Engineering
ISBN: 1527530361

Reinforced concrete columns play a very important role in structural performance. As such, it is essential to apply a suitable analytical tool to estimate their structural behaviour considering all failure mechanisms such as axial, shear, and flexural failures. This book highlights the development of a fiber beam-column element accounting for shear effects and the effect of tension stiffening through reinforcement-to-concrete bond, along with the employment of suitable constitutive material laws.

Reinforced Concrete Structures under Cyclic Loading

Reinforced Concrete Structures under Cyclic Loading
Author: Farhad Aslani
Publisher: Trans Tech Publications Ltd
Total Pages: 284
Release: 2015-03-14
Genre: Technology & Engineering
ISBN: 3038267236

Experimental programs in laboratories give real results to identify nonlinear behavior of reinforced concrete (RC) structures but they are limited to knowledge of particular cases under restricted structural dimensions, sizes, shapes, loading and boundary conditions but the computational simulation approach has no limit to its application. Constitutive models are developed to simulate the dynamic nonlinear response of concrete and steel reinforcement subjected to cyclic loading varying randomly in magnitude. The behavior of structural concrete under monotonic loading is affected by important material aspects including cracking, crushing, tension stiffening, compression softening and bond slip. Reversed cyclic loading introduces further complexities such as stiffness degradation in concrete and the Bauschinger effect in reinforcing steel. In this research the validity and reliability of some proposed constitutive models for concrete considering general loading i.e. cyclic, monotonic, partial, common point and transition loading are evaluated. Amongst many existing constitutive models, because of their simplicity and common usage in the finite element analysis of RC structures, only some common proposed models based on nonlinear elasticity-based approach are investigated. These models are verified against experimental data available in the literature and the results are discussed. In this study, also, a hysteretic stress–strain model is developed for unconfined concrete with the intention of providing efficient modeling for the structural behavior of concrete in seismic regions. The proposed model is based on the findings of previous experimental and analytical studies. The model for concrete subjected to monotonic and cyclic loading, comprises four components in compression and tension; an envelope curve (for monotonic and cyclic loading), an unloading curve, a reloading curve, and transition curve. Also presented are formulations for partial unloading and partial reloading curves. The proposed Constitutive model reliability is investigated by RC members non-linear finite element analysis (FEM) using by finite element software ABAQUS. Comparisons with test results showed that the proposed model provides a good fit to a wide range of experimentally established hysteresis loops.

Effect of Load Pattern and History on Performance of Reinforced Concrete Columns

Effect of Load Pattern and History on Performance of Reinforced Concrete Columns
Author: Fatemeh Shirmohammadi
Publisher:
Total Pages:
Release: 2015
Genre:
ISBN:

Accurate and realistic assessment of the performance of columns in general, and those in critical locations that may cause progressive failure of the entire structure, in particular, is significantly important. This performance is affected by the load history, pattern, and intensity. Current design code does not consider the effect of load pattern on the load and displacement capacity of columns. A primary research sponsored by Kansas Department of Transportation (KDOT) was conducted as the initial step of the present study (No. K-TRAN: KSU-11-5). The main goals of the KDOT project were: (1) investigation of new KDOT requirements in terms of the column design procedure and detailing and their consistency with AASHTO provisions; (2) verification of the KDOT assumptions for the plastic hinge regions for columns and bridge piers, (3) provide assessment of the load capacity of the existing columns and bridge piers in the light of the new specifications and using the new load demand as in the new provisions; and finally recommendations for columns and bridge piers that do not meet the new requirements. A conclusion was drawn that there is a need for conducting more studies on the realistic performance of Reinforced Concrete (RC) sections and columns. The studies should have included performance of RC members under various loading scenarios, assessment of columns capacity considering confinement effect provided by lateral reinforcement, and investigation on performance of various monotonic and cyclic material models applied to simulate the realistic performance. In the study reported here, monotonic material models, cyclic rules, and plastic hinge models have been utilized in a fiber-based analytical procedure, and validated against experimental data to simulate behavior of RC section under various loading scenarios. Comparison of the analytical predictions and experimental data, through moment-curvature and force-deflection analyses, confirmed the accuracy and validity of the analytical algorithm and models. The performance of RC columns under various axial and lateral loading patterns was assessed in terms of flexural strength and energy dissipation. FRP application to enhance ductility, flexural strength, and shear capacity of existing deficient concrete structures has increased during the last two decades. Therefore, various aspects of FRP-confined concrete members, specifically monotonic and cyclic behavior of concrete members confined and reinforced by FRP, have been studied in many research programs, suggesting various monotonic models for concrete confined by only FRP. Exploration of existing model performances for predicting the behavior of several tested specimens shows a need for improvement of existing algorithms. The model proposed in the current study is a step in this direction. FRP wrapping is typically used to confine existing concrete members containing conventional lateral steel reinforcement (tie/spiral). The confining effect of lateral steel reinforcement in analytical studies has been uniquely considered in various models. Most models consider confinement due to FRP and ignore the effect of conventional lateral steel reinforcement. Exploration of existing model performances for predicting the behavior of several tested specimens confined by both FRP and lateral steel shows a need for improvement of existing algorithms. A model was proposed in this study which is a step in this direction. Performance of the proposed model and four other representative models from literature was compared to experimental data from four independent databases. In order to fulfill the need for a simple, yet accurate analytical tool for performance assessment of RC columns, a computer program was developed that uses relatively simple analytical methods and material models to accurately predict the performance of RC structures under various loading conditions, including cyclic lateral displacement under a non-proportionally variable axial load (Esmaeily and Xiao 2005, Esmaeily and Peterman 2007). However, it was limited to circular, rectangular, and hollow circular/rectangular sections and uniaxial lateral curvature or displacement. In this regards, a computer program was developed which is the next generation of the aforesaid program with additional functionality and options. Triangulation of the section allows opportunity for cross-sectional geometry. Biaxial lateral curvature/displacement/force combined with any sequence of axial load provides opportunity to analyze the performance of a reinforced concrete column under any load and displacement path. Use of unconventional reinforcement, such as FRP, in lateral as well as longitudinal direction is another feature of this application.