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International Concrete Abstracts Portal

Showing 1-5 of 173 Abstracts search results

Document: 

SP-343_31

Date: 

October 1, 2020

Author(s):

Poveda, E.; Ruiz, G.; Cifuentes, H.; Yu, R.C.; Zhang, X.X.

Publication:

Symposium Papers

Volume:

343

Abstract:

This work proposes a new strain-based failure criterion for compression fatigue in steelfiber reinforced concrete. It is based on the Spark and Menzies’ relationship between the logarithm of the secondary strain rate per cycle and the specimen life expressed as the logarithm of the number of cycles until failure. This relationship permits calculating the critical strain at the failure of the specimen as the sum of two terms. The first one is the maximum strain in the first cycle due to the maximum compression stress. The second term is the increase of strain due to the remaining cycles until failure. Thus, failure occurs when the strain reaches a critical level during fatigue loading. On the contrary, the material continues resisting while its accumulated strain is lower than the critical one. This criterion is validated against a series of low-cycle fatigue tests in five types of concrete with different amounts of fiber that share the same concrete matrix. Besides, the experimental results show that the fibers delay the deformation and deterioration processes caused by fatigue. They also show that there is an optimum fiber content that maximizes fatigue life.


Document: 

SP-343_17

Date: 

October 1, 2020

Author(s):

Juhasz, K.P.; Schaul, P.

Publication:

Symposium Papers

Volume:

343

Abstract:

In the past decade macro synthetic fibre reinforcement has become widely used for concrete track slabs including tramlines. By using macro synthetic fibres as a reinforcement in concrete slabs both the casting time and manual work will decrease, while the concrete’s ductility will increase. In addition the durability will be higher with using synthetic fibres, and the carbon footprint will be lower compared to steel mesh or fibre reinforcement. In most cases the steel reinforcement can be omitted entirely from the structures using macro synthetic fibres. The uniformly distributed fibres in the concrete can increase the residual flexural strength of the concrete independently from the location. This makes it possible to use the fibres in both cast in situ and precast elements used for tramlines. The calculation process for these structures always has to comprise of both the static load, the dynamic load and the effect of cyclic loading, i.e. fatigue. These load calculations can be handled using advanced finite element analysis software, which is specialized for concrete and fibre reinforced concrete structures. The paper will present the opportunities for using macro synthetic fibres together with the process of designing fibre reinforced concrete tramlines.


Document: 

SP-341-08

Date: 

June 30, 2020

Author(s):

Ruchin Khadka, Mustafa Mashal, and Jared Cantrell

Publication:

Symposium Papers

Volume:

341

Abstract:

Recently titanium alloy bars (TiABs) have been gaining popularity in civil engineering applications. They offer good deformation capacity, better fatigue performance, high-strength-to-weight ratio, lighter weight (60% that of steel), and excellent corrosion resistance. Recently, TiABs were used in the strengthening of two bridges in Oregon to increase the shear and flexural capacities of the concrete beams. The research in this paper quantifies some common mechanical properties of TiABs using experimental investigation. This is done to explore suitability of the material for wider applications in civil infrastructure. The four types of testing conducted in accordance with ASTM standards included tension, hardness, Charpy V-Notch, and galling tests. Samples of 150 ksi (1034 MPa) high strength steel were also tested for comparison. Test results showed good performance of TiABs. Analytical models are proposed for stress-strain and toughness-temperature relationships.


Document: 

SP340

Date: 

April 30, 2020

Author(s):

Andrzej S. Nowak, Hani Nassif, Victor Aguilar

Publication:

Symposium Papers

Volume:

340

Abstract:

Professor Dennis Mertz passed away after a prolonged battle with cancer. He spent a large portion of his professional career working on advancing of the state-of-the-art of bridge engineering. He was a great friend and colleague to many at ACI and ASCE. Joint ACI-ASCE Committee 343, joined with ACI Committees 342 and 348, sponsored four sessions to honor his contributions and achievements in concrete bridge design and evaluation. These sessions highlighted the important work and collaborative efforts that Dr. Mertz had with others at ACI and ASCE on various topics. These sessions also combined the efforts among ACI and ASCE researchers and practitioners in addressing various topics related to the design and evaluation of concrete bridges. The scope and outcome of the sessions are relevant to ACI’s mission. They raise awareness on established design methodologies applied for various limit states covering topics related flexure, shear, fatigue, torsion, etc. They address problems related to emerging design and evaluation approaches and recent development in design practices, code standards, and related applications. The Symposium Publication (SP) is expected to be an important reference in relation to design philosophies and evaluation methods of new and existing concrete bridges and structures.


Document: 

SP-333_05

Date: 

October 1, 2019

Author(s):

Ruo-Yang Wu and Chris P. Pantelides

Publication:

Symposium Papers

Volume:

333

Abstract:

Two severely damaged concrete column-to-cap beam specimens were successfully repaired, using a carbon fiber-reinforced polymer (CFRP) cylindrical shell, non-shrink repair concrete, and headed steel bars. The first cast-in-place specimen experienced concrete crushing and longitudinal bars fracture/buckling; for the second precast specimen, the column was completely separated from the cap beam. In this paper, two analytical models, Model Fiber and Model Rotational Spring (RS), simulating the seismic performance of the repaired specimens are proposed. In Model Fiber, plasticity considering bond-slip effects was distributed over the defined plastic hinge length of the nonlinear beam-column element. In Model RS, a non-linear rotational spring was used to consider the concentrated plasticity located at the repaired cross-section. Low-cycle fatigue of the damaged column longitudinal steel bars was included in the analytical models. Simulations show that the analytical results, in terms of hysteretic response and moment-rotation, are in very good agreement with the experimental results. Model fiber performed better for predicting the pinching effect in the hysteretic response of the repaired cast-in-place specimen; Model RS performed better for matching the hysteresis curves of the repaired precast concrete specimen. In addition, Model Fiber was able to predict the local response of the columns including the fracture of longitudinal bars due to low-cycle fatigue.


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