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International Concrete Abstracts Portal

Showing 1-5 of 76 Abstracts search results

Document: 

SP327-33

Date: 

November 1, 2018

Author(s):

Mamdouh El-Badry, Mohammad Moravvej, and Parham Joulani

Publication:

Symposium Papers

Volume:

327

Abstract:

An experimental evaluation of a hybrid FRP-concrete slab-on-truss girder bridge system is presented. The girders consist of pretensioned top and bottom concrete chords connected by vertical and diagonal truss members made of concrete-filled fiber-reinforced polymer (FRP) tubes. The truss members are connected to the chords by means of long double-headed glass FRP (GFRP) bars. The chords are also reinforced with GFRP longitudinal bars and transverse stirrups. The deck slab is connected to the top chords of the girders using double-headed GFRP studs. The truss girders are thus lighter and more durable than the conventional precast I-girders. The experimental program consisted of fabricating and testing eight full-scale truss girders including four 2.83-m (9.28-ft) long 2-panel trusses and four 9.82-m (32.22-ft) long 8-panel trusses, all having the same cross-section dimensions with 1.32-m (4.33-ft) overall depth. Two of the 2-panel and two of the 8-panel girders were reinforced with GFRP reinforcement. The remaining four were reinforced with steel and used as control specimens. Two of the 2-panel and two of the 8-panel girders were covered with a one-meter wide concrete slab connected to the girder top chord by either steel or GFRP double-headed studs. Tests under static loading showed excellent performance of the system in terms of strength and stiffness.


Document: 

SP-330-08

Date: 

September 26, 2018

Author(s):

Ivan Janotka, Pavel Martauz, and Michal Bacuvcik

Publication:

Symposium Papers

Volume:

330

Abstract:

Hybrid cement (H-CEMENT) is an innovative cement of the producer from Slovakia. H-CEMENT is suitable for the production of ready-mixed concrete of compressive strength classes up to C 30/37 (4350/5370 psi) along with shrinkage-reducing and alkali-aggregate reaction-mitigating properties. The results of 5-years of exposure of H-CEMENT mortar in an aggressive sulfate solution are compared with two reference cement mortars made either with CEM I or sulfate-resistant CEM I SR 0. Sulfate resistance of H-CEMENT was evaluated in the regularly-renewed aggressive 5% solution by none-destructive tests (dynamic modulus of elasticity and length changes), destructive tests (flexural and compressive strength), microstructure studies (XRD, TG-DTA and SEM), wet chemical analyses (mainly the estimation of SO3 content), and pore structure technique (MIP). The results give evidence of the same high sulfate resistance for H-CEMENT as that for CEM I SR 0 with C3A = 0.


Document: 

SP328-03

Date: 

September 12, 2018

Author(s):

Vahid Sadeghian and Frank Vecchio

Publication:

Symposium Papers

Volume:

328

Abstract:

The Modified Compression Field Theory (MCFT) was introduced almost 40 years ago as a simple and effective model for calculating the response of reinforced concrete elements under general loading conditions with particular focus on shear. The model was based on a smeared rotating crack concept, and treated cracked reinforced concrete as a new orthotropic material with unique constitutive relationships. An extension of MCFT, known as the Disturbed Stress Field Model (DSFM), was later developed which removed some restrictions and increased the accuracy of the method. The MCFT has been adapted to various types of finite element analysis programs as well as structural design codes. In recent years, the application of the method has been extended to more advanced research areas including extreme loading conditions, stochastic analysis, fiber-reinforced concrete, repaired structures, multi-scale analysis, and hybrid simulation. This paper presents a brief overview of the original formulation and its evolvement over the last three decades. In addition, the adaptation of the method to advanced research areas are discussed. It is concluded that the MCFT remains a viable and effective model, whose value lies in its simple yet versatile formulation which enables it to serve as a foundation for accurately solving many diverse and complex problems pertaining to reinforced concrete structures.


Document: 

SP326-64

Date: 

August 10, 2018

Author(s):

Enzo Martinelli, Carmine Lima, Marco Pepe, Antonio Caggiano, and Ciro Faella

Publication:

Symposium Papers

Volume:

326

Abstract:

The present study aims at investigating the influence of Recycled Steel Fibers (RSFs) recovered from waste tires on the resulting post-cracking response of Fiber-Reinforced Concrete (FRC) mixtures, when they are employed for replacing conventional Industrial Steel Fibers (ISFs). It moves from the results of four-point bending tests carried out on a series of specimens made of Hybrid FRC, namely reinforced by both RFSs and ISFs. Then, the paper proposes a theoretical model based on a meso-mechanical formulation merged into a cracked-hinge approach. The model is capable of taking into account explicitly the diverse geometric and mechanical properties of RSFs and ISFs and, hence, it is employed for interpreting the results of the aforementioned bending tests. Some comparisons between the experimental results and the theoretical predictions are presented with the aim to corroborate the mechanical consistence of the proposed model.

Finally, it is worth highlighting that this study has been carried out at the STRuctural ENGineering Testing Hall (STR.ENG.T.H) of the University of Salerno, as part of the “SUPERCONCRETE” Project (H2020-MSCA-RISE-2014 – n. 645704).


Document: 

SP322-20

Date: 

June 18, 2018

Author(s):

Donna Chen and Raafat El-Hacha

Publication:

Symposium Papers

Volume:

322

Abstract:

Experimental and analytical investigation into the performance of a special bond system was conducted on small-scale mixed-mode bending (MMB) specimens for implementation in a full-scale hybrid bridge deck system. Full-depth threaded Glass Fiber Reinforced Polymer (GFRP) rods, as a proposed replacement for commonly used GFRP shear studs, in conjunction with an epoxy bonded coarse silica sand aggregate layer, were used at the bond interface between a pultruded GFRP plate and cast-in-place Ultra-High Performance Concrete (UHPC). Findings show that the presence of the threaded GFRP rods increased the strength of the system up to 250% while utilizing 25% of the rod capacity. The full potential of full-depth threaded GFRP rods for bond and crack control can be explored in greater detail in future studies, including the application of nut tightening forces to increase initial clamping forces at the bond interface.


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