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Showing 1-5 of 410 Abstracts search results

Document: 

SP-343_09

Date: 

October 1, 2020

Author(s):

Ferrara, L.; Asensio, E.C.; Lo Monte, F.; Snoeck, D.; De Belie, N.

Publication:

Symposium Papers

Volume:

343

Abstract:

The design of building structures and infrastructures is mainly based on four concepts: safety, serviceability, durability and sustainability. The latter is becoming increasingly relevant in the field of civil engineering. Reinforced concrete structures are subjected to conditions that produce cracks which, if not repaired, can lead to a rapid deterioration and would result in increasing maintenance costs to guarantee the anticipated level of performance. Therefore, self-healing concrete can be very useful in any type of structure, as it allows to control and repair cracks as soon as they to occur. As a matter of fact, the synergy between fibre-reinforced cementitious composites and selfhealing techniques may result in promising solutions. Fibres improve the self-healing process due to their capacity to restrict crack widths and enable multiple crack formation. In particular, cracks smaller than 30-50 μm are able to heal completely. Moreover, in the case of High Performance Fibre Reinforced Cementitious Composites (HPFRCC), high content of cementitious/pozzolanic materials and low water-binder ratios are likely to make the composites naturally conducive to self-healing. In this framework the main goal of this paper is twofold. On the one hand, a state-of-the-art survey on self-healing of fibre-reinforced cementitious composites will be provided. This will be analysed with the goal of providing a “healable crack opening based” design concept which could pave the way for the incorporation of healing concepts into design approaches for FRC and also conventional R/C structures. On the other hand, the same state-of-the-art will be instrumental in identifying research needs, which still have to be addressed for the proper use of self-healing fibre-reinforced cementitious composites in the construction field.


Document: 

SP-343_28

Date: 

October 1, 2020

Author(s):

Kitazawa, K.; Sato, Y.; Naganuma, K.; Kaneko, Y.

Publication:

Symposium Papers

Volume:

343

Abstract:

This paper attempts to investigate the effectiveness of Steel Chip Reinforced Polymer Cementitious Composite (SCRPCC) to reduce the seismic drift of high rise building by employing finite element method. Steel chips are produced when a steel plate is precisely machined on a numerically controlled lathe. To verify the influence of drying shrinkage on the structural performance of entire buildings, seismic response analyses of a 22-story RC wall building subject to drying shrinkage cracking are conducted. The analyzed building was damaged in 1985 Mexico Earthquake. In the analyses, drying shrinkage is considered by conducting the drying shrinkage cracking analyses before dynamic seismic vibration analyses to examine the influence of drying shrinkage. For each case of the analyses, two kinds of materials are used; ordinary concrete and SCRPCC. The shrinkage of 8,400-day drying period induces cracks in the walls of top floor as well as the first floor. The maximum drift of the building is increased in the NS direction by the shrinkage cracking while reduced in the EW direction. The maximum total drift of the building during the seismic vibration is reduced by 3.5% in the NS direction and 8.9% in the EW direction by using the SCRPCC instead of the ordinary concrete. The average crack width of the building is reduced by 11.1% by the SCRPCC.


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_12

Date: 

October 1, 2020

Author(s):

Barros, J.A.O.; Foster, S.J.

Publication:

Symposium Papers

Volume:

343

Abstract:

For the development of reliable physical-mechanical models for predicting the behaviour of fibre reinforced concrete structures at service and strength limit conditions, constitutive models simulating comprehensibly the governing phenomena must be used. In this context, simulating the post-cracking mechanisms of the fibres, and their symbiotic relationship with the cementitious matrix that surrounds them, is required for the development of realistic modelling approaches that accurately represent empirical observations. Several experimental test setups and inverse analysis procedures have been proposed to derive the fundamental stress-crack width ( –w) law, but a consensus still does not exists on the best strategy for its determination. In structures governed by shear, fibre reinforcement increases the stiffness and shear stress transfer across a crack, but a methodology to capture the contribution of fibres in this regards is challenging. To overcome this, a clear strategy is needed in deriving relationships that simulate fibre reinforcement mechanisms in the mobilized fracture modes and, also, develop design approaches capable of capturing the relevant contributions of the fibres. This study firstly reviews current inverse analysis models used to describe the tensile (Model I fracture) relationship for FRC and, secondly, discusses a newly proposed model, referred to as the integrated shear model (ISM). The ISM is developed from mesoscale observations from gamma- and X-ray imaging on FRC elements under Modes I and II fracture conditions. The resulting model is compared to test data reported in the literature and a good correlation is observed.


Document: 

SP341

Date: 

July 17, 2020

Publication:

Symposium Papers

Volume:

341

Abstract:

ACI Committees 441 – Reinforced Concrete Columns and 341A – Earthquake-Resistant Concrete Bridge Columns, Mohamed A. ElGawady Columns are crucial structural elements in buildings and bridges. This Special Publication of the American Concrete Institute Committees 441 (Reinforced Concrete Columns) and 341A (Earthquake-Resistant Concrete Bridge Columns) presents the state-of-the-art on the structural performance of innovative bridge columns. The performance of columns incorporating high-performance materials such as ultra-high-performance concrete (UHPC), engineered cementitious composite (ECC), high-strength concrete, high-strength steel, and shape memory alloys is presented in this document. These materials are used in combination with conventional or advanced construction systems, such as using grouted rebar couplers, multi-hinge, and cross spirals. Such a combination improves the resiliency of reinforced concrete columns against natural and man-made disasters such as earthquakes and blast.


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