International Concrete Abstracts Portal

Showing 1-5 of 1393 Abstracts search results

Document: 

SP365_07

Date: 

March 1, 2025

Author(s):

Serhan Guner

Publication:

Symposium Papers

Volume:

365

Abstract:

Current nonlinear modeling software for concrete frames typically employs line elements with plastic hinges defined at user-selected locations. While this is a simple and computationally efficient approach, a number of drawbacks limit its application. They include the challenges with defining the interacting shear and moment hinge curves, uncertainties with hinge locations and lengths, and difficulties in capturing the post-peak response. Two-dimensional continuum methods address these limitations, but their computational cost limits their applicability. This study presents an alternative modeling method, and associated computer software, with the objective of combining the simplicity of frame elements with the accuracy and result visualization capabilities of continuum methods. The method, developed in the last two decades, employs a distributed-plasticity, layered-section approach based on the Disturbed Stress Field Model (DSFM). The distributed-plasticity approach eliminates the need for defining plastic hinges while the DSFM enables capturing the shear, moment, and axial force interaction. The total-load and secant-stiffness formulation provides numerically stable solutions, even in the post-peak region. This paper presents an overview of the theoretical approach, unique aspects, and capabilities of this method. The validation studies undertaken for 148 experimental specimens, subjected to static (monotonic and cyclic) and dynamic (impact, blast, and seismic) load conditions, are also presented.

DOI:

10.14359/51746687


Document: 

SP365_09

Date: 

March 1, 2025

Author(s):

Amirali Bahnamiri and Trevor D. Hrynyk

Publication:

Symposium Papers

Volume:

365

Abstract:

This paper presents a review of different modeling techniques that have been proposed to employ visual concrete cracking measurements as input in ‘crack-based’ reinforced concrete analysis procedures. The suitability of a recently developed crack-informed modeling approach that incorporates concrete cracking measurements as model input, using an equivalent loading approach where concrete cracks are replaced by fictitious loads that induce similar damage, is examined for applications involving idealized RC panel elements presented in the literature. The procedure employs the formulations of the Disturbed Stress Field Model (DSFM) as the basis for cracked reinforced concrete material and compatibility modeling and a solution framework that permits simple implementation in smeared crack continuum analysis procedures. Preliminary results indicate that crack-based modeling procedures can be used to provide enhanced performance assessments of cracked RC components.

DOI:

10.14359/51746689


Document: 

CI4703Bischoff

Date: 

March 1, 2025

Author(s):

Peter H. Bischoff

Publication:

Concrete International

Volume:

47

Issue:

3

Abstract:

This is the second article in a five-part series on calculating deflections for members not meeting minimum thickness requirements in accordance with ACI CODE-318-19. It reviews the development of a new expression for the effective moment of inertia Ie used to calculate immediate deflection of cracked reinforced (nonprestressed) concrete flexural members at service load and justifies the need for a change.


Document: 

SP364

Date: 

December 19, 2024

Author(s):

ACI Committee 345

Publication:

Symposium Papers

Volume:

364

Abstract:

Serviceability is considered a critical factor in the management of concrete bridges and structures. Typical components for evaluating the serviceability limit state include cracking, deflection, and vibration. Additionally, to ensure the adequate performance of load-bearing members, proper evaluation methodologies should be adopted. Although numerous research projects have been undertaken to examine the serviceability and performance assessment of concrete bridges and structures, significant endeavors are still required to address unexplored challenges. Of interest are the development of simplified prediction and appraisal approaches; novel techniques for quantifying stress levels; serviceability criteria under unusual distress; and the characterization of structural responses when exposed to blast, wind, and seismic loadings. This Special Publication contains 11 papers selected from technical sessions held in the ACI Fall Convention in November 2024. The Editors wish to thank all contributing authors and anonymous reviewers for their rigorous efforts. The Editors also gratefully acknowledge Ms. Barbara Coleman at ACI for her knowledgeable guidance. Yail J. Kim, University of Colorado Denver, Editor Hyeon-Jong Hwang, Konkuk University, Editor

DOI:

10.14359/51745486


Document: 

CI4610ConcreteQA

Date: 

October 1, 2024

Publication:

Concrete International

Volume:

10

Issue:

46

Abstract:

The general purpose of reinforcing bars in slabs-on-ground is to control crack widths at the top surface of a slab. As the amount of reinforcement increases across the joint, the probability of out-of-joint cracking increases, as tighter cracks may occur at closer spacing than the joints. The Q&A provides some guidance on the amount of reinforcement crossing the joint and its role.


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