International Concrete Abstracts Portal

ABOUT THE INTERNATIONAL CONCRETE ABSTRACTS PORTAL

  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

Showing 1-10 of 915 Abstracts search results

Document: 

19-006

Date: 

January 1, 2020

Publication:

Materials Journal

Volume:

117

Issue:

1


Document: 

18-554

Date: 

January 1, 2020

Author(s):

Titchenda Chan, Kevin R. Mackie, and Zachary B. Haber

Publication:

Structural Journal

Volume:

117

Issue:

1

Abstract:

In high seismic regions, prefabricated columns have seen limited applications because the connections generally coincide with the plastic hinge (PH) region, where major damage occurs. This paper proposes a simple and damage-tolerant precast column connection for use in medium and high seismic regions that uses ultra-high-performance concrete (UHPC). The connection laps the longitudinal reinforcement from precast column with footing dowel bars using a short splice length, a practical reinforcing bar cover, and no shear reinforcement within the connection region. High-strength bars were used as the footing dowels to shift PH formation above the connection region to prevent footing damage due to inelastic strain penetration, and ensure the target lateral load and displacement ductility capacity. The connection was investigated experimentally by testing two 0.42-scale precast columns (flexural and flexural-shear) under reversed cyclic loading. Responses of the precast columns were compared with two reference cast-in-place (CIP) columns. Results indicate that the proposed connection performed well in shear, developed the column longitudinal bars, shifted PH formation above the UHPC region, and exhibited similar or improved lateral capacity and ductility compared with the CIP columns.

DOI:

10.14359/51718021


Document: 

18-539

Date: 

January 1, 2020

Author(s):

Shih-Ho Chao

Publication:

Structural Journal

Volume:

117

Issue:

1

Abstract:

While the size effect on ultimate shear strength of plain concrete (PC) slender beams has been extensively researched in the past decades, limited tests have been carried out to study the extent and mechanism of size effect in steel fiber-reinforced concrete (SFRC) beams. ACI 318-19 restricts the use of steel fibers as the minimum shear reinforcement to beams with a height of up to 24 in. (610 mm). In this study, in addition to analyzing available testing data, an experimental study was carried out on a series of SFRC beams with a range of heights including 12, 18, 24, 36, and 48 in. (305, 457, 610, 915, and 1220 mm). A digital image correlation (DIC) technology with a full-field deformation measuring capability was used to identify the underlying factors that cause size effect on the ultimate shear strength of SFRC slender beams. The results are distinctive because they dispute the conventional hypothesis by correlating the size effect of the ultimate shear strength on SFRC beams to the effects of the compression zone and dowel resistance, rather than by simply lowering the aggregate interlock or fiber bridging capacity in larger SFRC beams due to a wider critical crack. Consequently, a less robust dowel zone such as one lacking well-distributed steel fibers or an inadequate fiber dosage can result in early failure of dowel resistance and subsequent shear failure, which intensifies the size effect.

DOI:

10.14359/51718018


Document: 

18-533

Date: 

January 1, 2020

Author(s):

Bo Hu and Tribikram Kundu

Publication:

Structural Journal

Volume:

117

Issue:

1

Abstract:

Post-earthquake investigations have shown that the beam-column joint is one of the weakest links in reinforced concrete moment-resisting frames under severe ground motions. An extensive study on natural aggregate concrete (NAC) beam-column joints has been conducted. However, few studies have examined the seismic performance of beam-column joints made with recycled aggregate concrete (RAC), especially for RAC roof-level exterior beam-column joints. In this paper, a series of RAC roof-level exterior beam-column joints were fabricated and subjected to reversed cyclic loadings. The ductility capacity, energy dissipation capacity, equivalent viscous damping, and load-deformation behavior of each specimen were evaluated. OpenSees was adopted to perform the finite element analyses. The numerical simulation predictions show good agreement with test results. The equations for joint shear strength determination proposed in this work exhibit a better correlation between experimental and theoretical values.

DOI:

10.14359/51718017


Document: 

18-521

Date: 

November 1, 2019

Author(s):

Gloria Faraone, Tara C. Hutchinson, Roberto Piccinin, and John Silva

Publication:

Structural Journal

Volume:

116

Issue:

6

Abstract:

Post-installed anchors connect various components to concrete members, which undergo cyclic cracking during a seismic event. In recognition of this, current guidelines to qualify anchors for seismic applications require adequate performance in cracked concrete without substantial load loss. The interaction between anchors and pure flexural cracks has been studied for decades; however, the response of anchors to shear and x-type (crossing) cracks—that is, the complex situation realized in shear-flexure structural components—has been neglected. Hence, the behavior of expansion and bonded anchors installed horizontally in a slender full-scale reinforced concrete shear wall was investigated, while the wall, whose response is described in a companion paper, was subjected to cyclic lateral loading. Results confirm the sensitivity of the performance of expansion anchors amidst the presence of a variety of cracked concrete conditions. Nonetheless, both bonded and expansion anchors demonstrate sufficient residual axial load capacity and post-peak strength during pullout tests to failure.

DOI:

10.14359/51718069


Document: 

18-520

Date: 

November 1, 2019

Author(s):

Gloria Faraone, Tara C. Hutchinson, Roberto Piccinin, and John Silva

Publication:

Structural Journal

Volume:

116

Issue:

6

Abstract:

Within a building, anchors are essential for the connection of various nonstructural systems to reinforced concrete elements, including shear walls. During an earthquake, anchors in reinforced concrete shear walls need to retain strength and stiffness, despite the presence of cracks, which develop during lateral cyclic loading. To investigate the behavior of post-installed anchors in walls that develop shear-flexural cracks, a slender full-scale wall is designed and constructed according to current U.S. design codes. Seismic loading was imposed on the wall through an equivalent cyclic displacement history applied at the wall top. The specimen failed in flexure, precipitated by buckling and fracture of the boundary reinforcement. The local and global response of this full-scale specimen is documented herein, with particular emphasis on the evolution of cracking. Such cracks result in boundary conditions to the anchors, whose behavior is discussed in a companion paper.

DOI:

10.14359/51718068


Document: 

18-488

Date: 

November 1, 2019

Author(s):

Scott J. Menegon, John L. Wilson, Nelson T. K. Lam, and Emad F. Gad

Publication:

Structural Journal

Volume:

116

Issue:

6

Abstract:

This paper presents an overview and results of a recent experimental testing program of nonductile reinforced concrete (RC) wall boundary elements. The experimental program consisted of 17 boundary element prism specimens that are meant to represent the end regions of nonductile RC walls. The failure mechanisms of interest were global out‐of‐plane buckling and local bar buckling of the vertical reinforcement. The matrix of test specimens included: high and low slenderness ratios (that is, height-to-thickness ratio); cast-in‐place and precast wall construction methods; and specimens that were detailed with either a single central layer of vertical reinforcement or two layers of vertical reinforcement, one per face. Strain-rate affects were also assessed in the experimental program. The paper concludes with a detailed discussion of the test results, comparisons with similar experimental programs and design models in literature, and guidance on tensile strain limits for the displacement-based design of nonductile RC walls.

DOI:

10.14359/51718008


Document: 

18-430

Date: 

November 1, 2019

Author(s):

Moayyad Al-Nasra

Publication:

Materials Journal

Volume:

116

Issue:

6

Abstract:

Researchers have struggled to come up with accurate and convenient tools to measure concrete strength in tension. Several indirect experimental tests of concrete in tension are used to measure the concrete strength in tension, including the splitting test and the beam test. None of the indirect methods measures the true tensile strength of concrete; at the same time, there is no widely acceptable direct tensile test. In this study, a new testing procedure is introduced to measure the concrete strength in tension by subjecting a hollow concrete cube to internal water pressure. The hollow concrete cube will fail due to excessive circumferential/hoop stress, which is pure tensile stress. The maximum hoop stress that causes the hollow cube to fail in tension is taken as the concrete tensile strength. The hollow cubes were subjected to internal water pressure. New simulation theoretical finite element model was also developed to validate the experimental results.

DOI:

110.14359/51715588


Document: 

18-426

Date: 

November 1, 2019

Author(s):

Philipp Riedel, Torsten Leutbecher, Siemon Piotrowski, and Christian Heese

Publication:

Materials Journal

Volume:

116

Issue:

6

Abstract:

So far, there has been a lack of generally applicable factors to convert between compressive strengths obtained in tests on ultra-high-performance concrete (UHPC) specimens of different shapes and sizes. Thus, a test program covering compression tests on 150 and 100 mm (6 and 4 in.) cylinders and cubes was initiated. For comparison reasons, ordinary-performance concrete (OPC), high-performance concrete (HPC), and UHPC mixtures without fibers were examined. The maximum aggregate size of the UHPC mixtures was 0.5, 3, 5, and 8 mm (0.020, 0.12, 0.20, and 0.31 in.), which covers the scope of application. The mean cylinder compressive strengths ranged between 30 and 200 MPa (4.35 and 29.0 ksi). Very small coefficients of variation of test results document high accuracy and validity obtained by standardized procedures throughout fabrication and testing. Compared with OPC and HPC, the effect of specimen’s geometry on the compressive strength is very small for UHPC.

DOI:

10.14359/51716983


Document: 

18-412

Date: 

November 1, 2019

Author(s):

Zhiyong Liu, Sen Gao, Weiwei Chen, Yunsheng Zhang, and Cheng Liu

Publication:

Materials Journal

Volume:

116

Issue:

6

Abstract:

Unlike traditional experimental testing, some procedures have been developed for the characterization of microstructures of cement-based materials. Based on the microstructure of the cement hydration model obtained from a digital image-based model, the parameters of pore structure were in-place continuously determined by CEMHYD3D. The characteristic parameters of pore include total porosity, the continuous pore, isolated pore, dead-end pore, connectivity, pore size distribution, specific surface area, and tortuosity. According to the combustion algorithm, the three-dimensional (3-D) voxel-erosion method, the mercury intrusion porosimetry simulation, the continuous PSD algorithm, and the random walk algorithm, the physical models are developed into program to obtain the characteristic parameters of pore structure evolution. The results show that the dead-end pores and the isolated pores begin to decrease after the continuous pores disappear. The pore size distribution of the pore structure is calculated with finer resolution. The water-cement ratio (w/c) and hydration degree have a significant effect on the specific surface area of the pores. With the increase of the degree of hydration, the tortuosity of the pore structure increases gradually. Finally, the simulation results are compared to the experimental values and the literature data that have a good agreement.

DOI:

10.14359/51716978


12345...>>

Results Per Page