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International Concrete Abstracts Portal

Showing 1-5 of 35 Abstracts search results

Document: 

SP326-57

Date: 

August 10, 2018

Author(s):

Vladimir Kakusha, Oleg Kornev, Mikhail Kovalev, Andrey Lapshinov, and Egor Litvinov

Publication:

Symposium Papers

Volume:

326

Abstract:

This paper represents the summary of the design criteria and construction details for the GFRP (glass fiber-reinforced polymer) reinforced foundation slab. The idea was to improve the foundation slab durability by using GFRP bars. This included the use of GFRP bars as main longitudinal reinforcement for the foundation slabs which represents the world first application of this type. During the design procedures, several non-standard issues related to GFRP reinforcement have been solved. The method statement has been created for Construction Company with the consideration of the specific properties of GFRP bars in comparison to steel reinforcement. Before the casting of concrete, strain gauges were attached to GFRP bars and concrete surface to control the strains during the erection and the maintenance of building.


Document: 

SP322-17

Date: 

June 18, 2018

Author(s):

Hai Nguyen, Hiroshi Mutsuyoshi, and Wael Zatar

Publication:

Symposium Papers

Volume:

322

Abstract:

This work presents an experimental investigation of composite girders consisting of precast Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) slabs placed on pultruded Fiber-Reinforced Polymer (FRP) Igirders. Two control girder specimens and seven large-scale composite girders were tested under static four-point bending. Two series of the FRP-UHPFRC composite girders were examined. H-series girders composed of hybrid carbon/glass FRP (HFRP) I-girders topped with either full-length precast UHPFRC slabs or segmental counterparts. G-series girders included segmental UHPFRC slabs placed on glass-fiber-reinforced polymer (GFRP) I-girders. Twelve precast UHPFRC segments were used in each slab of the segmental composite girders. Either high-strength mortar or epoxy adhesive were used to join the precast UHPFRC segments. The test results revealed that the flexural stiffness of the composite girder with the epoxy-connected segmental precast slabs is almost identical to that of the full-length precast composite girder. The mortar-connected girder exhibited slightly more ductile behavior than the epoxy-connected girder. The G-series girder with thick GFRP plate externally bonded to the soffit of the GFRP Igirder showed pseudo-ductile behavior. All the composite girders demonstrated significant improvements in flexural stiffness and moment-carrying capacity compared with the control FRP I-girders without the UHPFRC slabs.


Document: 

SP322-03

Date: 

June 18, 2018

Author(s):

Yuanli Wu, Amr El Ragaby and Shaohong Cheng

Publication:

Symposium Papers

Volume:

322

Abstract:

Precast, prestressed hollow core (PHC) slabs are among the most common concrete deck system in the world. However, due to the manufacturing constraints and the difficulty in providing internal shear reinforcement, the shear capacity of PHC slabs sometimes dictates the design and reduces the efficiency and economics of PHC slabs. The objective of this research project is to develop an innovative application of externally bonded Fiber-Reinforced Polymers (FRP) sheets by installing the sheets along the internal perimeter of the slab voids to strengthen the webshear capacity of PHC slabs. To explore the feasibility and to optimize the new technique, experimental testing was carried out on eight full-scale single web, I shape, specimens (each of 4575 mm “180 in” long, 300 mm “12 in” thick and a 284 mm “11.2 in” wide) that were cut longitudinally out of the PHC slab. Carbon FRP sheets were bonded along the full perimeter on each side of the web specimens. The test specimens were loaded monotonically until failure under single concentrated load at a shear span/depth ratio of 2.5. The investigated parameters were the width of the FRP strengthened zone (300 “12 in.”, 450 “18 in.”, and 600 mm “24 in.”) and the number of strengthening layers (2 and 4 layers). The test results showed the efficiency of the proposed technique to enhance the shear strength of PHC slabs.


Document: 

SP-315_16

Date: 

April 1, 2017

Author(s):

Dritan Topuzi, Maria Anna Polak, Sriram Narasimhan

Publication:

Symposium Papers

Volume:

315

Abstract:

The focus of this research is on developing new punching shear retrofit techniques for slab-column connections to improve the seismic response of flat-plate systems. Previous tests have shown the effectiveness of using shear reinforcement to enhance the shear strength and ductility of individual slab-column connections. However, the advantage of ductility in reducing the earthquake impact on structures is accompanied by an increase in the base shear, due to increased stiffness. Herein, a new type of punching shear retrofit element, shear bolts with flexible washers, is introduced. The flexible washers allow for shear crack opening during the lateral displacements, while at the same time providing control of the crack width by controlling the washer thickness and/or stiffness. The results show that this technique increases the ductility of the connections, without a commensurate increase in stiffness. The effect of this type of shear reinforcement on the response of an assembled structure is investigated through dynamic analysis, to check how energy dissipation within individual connections affects the overall energy dissipation of a flat-plate system. The presented system was designed for slab retrofit. However, it can be anticipated that similar concepts could be used in the construction of new slabs in seismic zones.


Document: 

SP-315_18

Date: 

April 1, 2017

Author(s):

Thai X. Dam, James K. Wight, Gustavo J. Parra-Montesinos, Alex DaCosta

Publication:

Symposium Papers

Volume:

315

Abstract:

Seventeen large-scale interior reinforced concrete slab-column connections were tested to study the effect of different shear stud layouts and the percentage of slab flexural reinforcement. They were divided into two series M (twelve specimens) and S (five specimens) based on their dimensions. Each specimen in Series M had a 6 ft by 6 ft (1830 mm by 1830 mm) and 8 in. (200 mm) thick slab and a 6 in. by 6 in. (150 mm by 150 mm) column cross-section, while each specimen in Series S had a 10 ft by 10 ft (3050 mm by 3050 mm) and 10 in. (250 mm) thick slab and a 12 in. by 12 in. (300 mm by 300 mm) column cross-section. The percentage of slab flexural tension reinforcement was approximately either 0.8% or 1.2%, and shear studs were arranged in either an orthogonal or radial layout. Test results showed that shear strength equations in the ACI Building Code (ACI 318, 2014) overestimated the strength of some test specimens. Also, specimens with a radial layout of shear studs typically had higher strength and more ductile behavior than specimens with an orthogonal stud layout. Recommendations to improve the design of flat plate systems are presented.


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