A simplified damage mechanics approach to nonlinear analysis of frames

Elasto-plastic large deformation analysis of thin-walled structures

A refined R.C. beam element including bond-slip relationship for the analysis of continuous beams

A complementarity approach for elastoplastic analysis of strain softening frames under combined bending and axial force

In this work, we present a new finite element for (geometrically linear) Timoshenko beam model for ultimate load computation of reinforced concrete frames. The proposed model combines the descriptions of the diffuse plastic failure in the beam-column followed by the creation of plastic hinges due to the failure or collapse of the concrete and of the re-bars. A modified multi-scale analysis is performed in order to identify the parameters for stress-resultant-based macro model, which is used to described the behavior of the Timoshenko beam element. For clarity, we focus upon the micro-scale models using the multi-fiber elements with embedded displacement discontinuities in mode I, which would typically be triggered by bending failure mode. More general case of micro-scale model capable of describing shear failure is described by Ibrahimbegovic et al. (Int J Numer Methods Eng 83(4):452---481, 2010).

Stress-resultant models for ultimate load design of reinforced concrete frames and multi-scale parameter estimates

Computer analysis of elastic-plastic structures

The objective of this paper is to explore the potential of the lumped-plasticity program STRUPL-1C and to illustrate its use as a practical engineering tool for the nonlinear analysis of concrete structures. This result is achieved through the development of a moment-rotation constitutive law that uses realistic material laws and is valid for any reinforced, prestressed and partially prestressed concrete planar frame at all behavioral states along the loading history. The effects of the main parameters that influence the moment-rotation relationship are investigated and discussed. Finally, the developed constitutive law is applied to the nonlinear analysis of a few reinforced and prestressed concrete continuous beams. Comparison to both experimental tests and more-complex nonlinear analysis techniques proves the accuracy of solutions obtained by the STRUPL-1C computer program. The examples reported also prove that the proposed approach enables considerable simplification of the structural model required for a historical nonlinear analysis of concrete structures and demonstrate the high potential of the approach with respect to its use in engineering practice.

Engineering Approach to Nonlinear Analysis of Concrete Structures

This paper investigates in detail the flexural ductility of structural concrete section, i.e., reinforced concrete (RC), prestressed concrete (PC), and partially prestressed concrete (PPC) sections. Flexural ductility is defined sas the ratio of the section ultimate and yield curvatures. Realistic, rather than conventional, standard estimates are attempted on the basis of actual material behavior states, and unified analysis of structural concrete sections. The effects of section shape, degree of prestressing, material laws, compression reinforcement, and other parameters are considered. Finally, some ACI Code revisions are proposed.

Flexural ductility of structural concrete sections

A computer system for various STRUctural PLasticity (STRUPL) analysis problems was recently developed and reported on. As a background to its possible adoption in engineering practice, this paper explores the theoretical and computational features of the computer system as applied to planar frameworks of practical significance. The system capability is illustrated for three examples, including steel and concrete structures subjected to various stress conditions and loading histories.

A Computer System for the Elastic-Plastic Analysis of Large-Scale Structures∗

Yield safety is introduced as a variable that controls both the cracking under service conditions and the permissible redistribution of ductile structural concrete frameworks at the ultimate limit state. Limiting values of the yield safety that ensure satisfaction of the code-specified cracking criteria are derived from the results of a comprehensive computer investigation. A parametric study of the yield-safety factor against cracking identifies the reinforcing index, ω, the allowable crack width \Iw\da\N (or concrete tensile strength \If\dr\N), and the degree of prestressing, γ, as the governing factors in cracking control. These factors, along with the live-to-total service load ratio \IW\dL\N/\IW\N, which affects the overall safety of the structure, determine the permissible moment redistribution of concrete frameworks. Numerical examples of design (with concurrent satisfaction of the ultimate and serviceability limit states) and analysis of cracking serviceability criteria, in agreement with ACI 318-89 code requirements, illustrate the application of the concepts presented.

M. Z. Cohn

Papers

Computer analysis of elastic-plastic structures

Engineering Approach to Nonlinear Analysis of Concrete Structures

Flexural ductility of structural concrete sections

A Computer System for the Elastic-Plastic Analysis of Large-Scale Structures∗

Yield safety, cracking control, and moment redistribution