Civil Engineering M.Sc. Thesis Presentation and Defense by Sobita Gurung
Master's Candidate: Sobita Gurung
Supervisor: Dr. Sam Salem
Internal Examiner: Dr. Ahmed Elshaer
External Examiner: Dr. Ahmed Mostafa (Ryerson University)
Thesis Title: LOAD RATIO EFFECTS ON THE STRUCTURAL FIRE BEHAVIOR OF GFRP-REINFORCED CONCRETE BEAMS WITH STRAIGHT- AND HOOKED-END BAR LAP SPLICES
Date and time: Tuesday, January 26th, 2021, between 3:00 P.M. and 5:00 P.M.
Zoom meeting:
Dr. Sam Salem (Director, Civil Engineering Graduate Programs) is inviting you to a scheduled Zoom meeting.
Topic: Master's Thesis Defense and Presentation by Sobita Gurung
Time: Jan 26, 2021 03:00 PM Eastern Time (US and Canada)
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https://lakeheadu.zoom.us/j/92421191854?pwd=WHBpeHdIZVJQcXdUQkZDY0loOHky...
Meeting ID: 924 2119 1854
Passcode: 163469
Abstract:
For a few decades glass fibre-reinforced polymers (GFRP) have been gaining acceptance as an alternative material to steel in manufacturing reinforcing rebars for concrete structures to enhance their durability especially those structures which are susceptible to corrosion. The good engineering properties, such as high chemical and corrosion resistance and high strength-to-weight ratio, make GFRP a desirable engineering material. However, the application of GFRP-reinforced concrete is still mostly limited to only certain components in bridges and marine structures where fire is not a primary consideration. Conventionally, steel is the reinforcement in tension in concrete structural elements. The properties of both steel and concrete at high temperature are well studied thus, it is easier to predict the behavior of steel-reinforced concrete structures in fire. However, the structural behavior of GFRP-reinforced concrete elements at elevated temperatures is yet to be understood well since very limited research has been done in this regard, which restricts its broader utilization. The primary objective of this research is to study the effect of load ratio on the structural behaviour of GFRP-reinforced concrete beams having straight- and hooked-end bar lap splices.
In this experimental study, four large-scale GFRP-reinforced concrete beams having lap splices at the beam midspan were subjected to elevated temperatures that followed the CAN/ULC-S101 standard fire time-temperature curve while being monotonically loaded. All four 2750-mm long beams had cross-sectional dimensions of 300 mm wide x 350 mm high, and were subjected to 80% load ratio of the beam ultimate design moment as per the beam design according to CSA-S806-12 standard. Two beams had straight-end bar lap splices, whereas the other two had hooked-end bar lap splices in the beam midspan. During fire tests, the beams were subjected to four-point flexure bending with two-point loads being 1000 mm apart. The results obtained in this study were then compared with the outcomes of a prior study conducted by Nour (2019) on identical beams but subjected to half of the applied load (40% load ratio of the beam ultimate design moment). It was observed that for the beams with hooked-end bar lap splices, the effect of load ratio on fire resistance time was significant, as the application of the higher load ratio reduced the fire resistance time of the beam by approximately 60 minutes. However, there was almost no effect of the applied load ratio increase on the fire resistance time of the beams with straight-end lap splices. The fire resistance time was mainly affected by direct exposure of GFRP bars to the fire during the experiments, however for beams with straight-end bar lap splices the pre-cracks were very small to expose bars to fire directly and extreme cracks did not occur until a few minutes before beam failure. Thus, direct fire exposure time of GFRP bars for beams having straight end lap splices was not significantly long to impact the fire resistance time.