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International Concrete Abstracts Portal

Showing 1-5 of 81 Abstracts search results

Document: 

SP-344_09

Date: 

October 1, 2020

Author(s):

Camilo Granda Valencia and Eva Lantsoght

Publication:

Symposium Papers

Volume:

344

Abstract:

This paper provides a practical example of the torsion design of an inverted tee bent cap of a three-span bridge. A full torsional design following the guidelines of the ACI 318-19 building code is carried out and the results are compared with the outcomes from CSA-A23.3-04, AASHTO-LRFD-17, and EN 1992-1-1:2004 codes. Then, a summary of the detailing of the cross-section considering the reinforcement requirements is presented. The objective of this paper is to illustrate the application of ACI 318-19 when designing a structural element subjected to large torsional moments.


Document: 

SP-344_11

Date: 

October 1, 2020

Author(s):

Thomas T. C. Hsu and Yagiz Oz

Publication:

Symposium Papers

Volume:

344

Abstract:

This paper presents the design of a cantilever canopy and its supporting beam for a sport stadium. The reinforced concrete beam is analyzed and designed under the effects of shear load, bending moment, and torsion. The design was carried out following the American Concrete Institute’s most recent standard (ACI 318-19). When there is torsion on reinforced concrete sections, the design steps become more complicated. The formula to design and the minimum requirements for both the longitudinal and transverse bars are changed since the torsion is included. The design of flexural longitudinal bars is not affected from torsion however, there are needed more longitudinal bars against torsion which affect the spacing and the detailing of longitudinal bars. For transverse bars, when the torsion is considered, the stirrups are designed as the sum of transverse and shear requirement. The main focus of the paper is to show the design steps and detailing of structural concrete elements under the effect of torsional moment.


Document: 

SP-343_32

Date: 

October 1, 2020

Author(s):

Antroula, G.; Stavroula, P.

Publication:

Symposium Papers

Volume:

343

Abstract:

With the advent of strain hardening fiber reinforced cementitious composites (SHFRCC) the development of a new generation of structural systems that benefit from the inherent ductility of concrete in tension in order to reduce the amounts of transverse reinforcement (stirrups), shear strength, and tension-force development capacity to the main reinforcement is possible. In this study a number of tests are conducted to explore the behavior of SHFRCC materials under cyclic loads, simulating seismic effects. The experimental responses of two half-scale interior beam column connections subjected to reversed cyclic loading are compared; one of the connections was constructed with a cementitious matrix without fibers, and was detailed according with the Eurocode provisions for ductility class M (moderate, μ=3.5). The other connection was constructed with a SHFRCC mix; (2% by volume of PVA fibers was used to reinforce the matrix and the minimum amount of shear reinforcement allowed by Eurocode 2 for non-seismic detailing was used in the specimens). Several supporting experiments were also conducted to support analysis of the cyclic behavior (uniaxial tension, compression, splitting tests). The behavior of the members under reversed cyclic displacement is also simulated with advanced nonlinear Finite Element Analysis, with results that are correlated with the experimental observations. The SHFRCC specimen with minimum detailing showed improved performance and enormous ductility suggesting new possibilities to the seismic design of structures.


Document: 

SP-343_14

Date: 

October 1, 2020

Author(s):

Winterberg, R.; Rodrìguez, L.M.; Cámara, R.J.; Abad, D.S

Publication:

Symposium Papers

Volume:

343

Abstract:

Fibre reinforced concrete (FRC) is becoming widely utilized in segmental linings due to the improved mechanical performance, robustness and durability of the segments. Further, significant cost savings can be achieved in segment production and by reduced repair rates during temporary loading conditions. The replacement of traditional rebar cages with fibres further allows changing a crack control governed design to a purely structural design with more freedom in detailing. Macro synthetic fibres (MSF) are non-corrosive and thus ideal for segmental linings in critical environments. Although fibre reinforcement for segments is relatively new, recent publications such as the ITAtech “Guidance for precast FRC segments – Volume 1: Design aspects” or the British PAS 8810 “Tunnel design – Design of concrete segmental tunnel linings – Code of practice” have now given more credibility to this reinforcement type and the basis for design. This paper presents and discusses the design methodology for precast tunnel segments and in particular the tasks associated with the use of MSF reinforcement. Temporary loadings as well as long term load behaviour will be addressed. A case history from the Santoña–Laredo General Interceptor Collector, currently under construction in northern Spain, will illustrate the specific benefits of MSF reinforcement for segmental linings.


Document: 

SP-341-03

Date: 

June 30, 2020

Author(s):

Hyun-Oh Shin, Hassan Aoude and Denis Mitchell

Publication:

Symposium Papers

Volume:

341

Abstract:

Ultra-high-performance concrete (UHPC) is an innovative material that exhibits high compressive and tensile strength as well as excellent durability. The provision of fibers in UHPC results in improved ductility and increased toughness when compared to conventional high-strength concrete. These properties make UHPC well-adapted for use in the columns of high-rise buildings and heavily-loaded bridges. This paper summarizes the results from a database of tests examining the effects of various design parameters on the axial load performance of UHPC columns. Experimental results illustrating the effects of concrete type (UHPC vs. high-strength and ultra-high-strength concrete), UHPC compressive strength and transverse reinforcement detailing are presented. The results show that the use of UHPC in columns resulted in increased load carrying capacity and post peak ductility when compared to conventional high-strength or ultra-high-strength concrete due to the ability of steel fibers to delay cover spalling. However, greater amounts of confinement reinforcement were required to achieve the same level of axial load performance as the UHPC compressive strength was increased from 150 to 180 MPa. The results also showed that the amount, spacing, and configuration of transverse reinforcement, as well as their interaction significantly affected the axial load response of UHPC columns. However, increasing the amount of transverse reinforcement had the most pronounced effect on post-peak behavior. The effect of the confinement provisions in current codes (CSA A23.3-14 and ACI-318-14) on the ductility of the UHPC columns was also investigated. Based on the results, an alternative confinement expression for achieving ductile behavior in UHPC columns was proposed.


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