Research on seismic resistance and mechanic behavior of reinforced lightweight aggregate concrete walls after high temperature

Abstract

SUMMARY This study focused on the mechanical behavior of reinforced lightweight aggregate concrete (RLAC) walls under repeated horizontal loads after a standard temperature‐rising fire‐resistance test and compared the specimen walls' ultimate loads, yielding loads, cracked loads, stiffness, and ductility with those of reinforced normal‐weight aggregate concrete (RNAC) walls. Steel reinforcing bar spacing, aggregate types, wall widths, and high temperatures were variables in this study. The experimental results showed that, after the fire‐resistance test, the smaller the steel reinforcing bar spacing of RLAC walls, the higher the yield and ultimate loads, yet the worse the ductility and the hysteresis loop's energy, whereas the greater the width of the wall, the greater the stiffness and the higher the hysteresis loop's energy. The differences in terms of stiffness, ductility, and hysteresis between RLAC walls with and without the fire‐resistance test were insignificant, indicating that RLAC walls do not lose their basic mechanical behavior during a high‐temperature fire. RNAC walls showed, indeed, a significant downward trend for strength and hysteresis after the fire‐resistance test, but the decrease was much less clear for stiffness. Therefore, RLAC walls did show better seismic resistance than RNAC walls under the same testing conditions. Copyright © 2013 John Wiley & Sons, Ltd.

Failure Patterns of Reinforced Lightweight Aggregate Concrete (RLAC) Walls after High Temperature

“…According to ASTM E119, the temperature in the furnace needs to reach 700°C within 10 minutes, and the heating shall continue for another 50 minutes until the final temperature reaches 950°C [3].…”

“…In contrast to most past research, which concentrate on the seismic capacity of NWAC, fewer research were conducted on RLAC walls, especially in the field of mechanics behavior of walls under repeated horizontal loads. Therefore, this paper explores the mechanics behavior of RLAC walls under the lateral effect of repeated horizontal loads after the fire-resistance test under standard temperature condition, as well as the results of the failure patterns of the wall specimens to evaluate the seismic resistance of RLAC after being treated with high temperature [3].…”

Using the microstructure and mechanical behavior of steel materials to develop a new fire investigation technology

“…Once the steel temperature reaches 550°C, yielding strength is reduced by nearly 60%, and when the temperature reaches 600°C, it is reduced by another 50%. According to the standard temperature rising curve provided by American Society for Testing and Materials (ASTM) E 119 and ISO 834, if a fire lasts for 20 minutes, the temperature at the fire scene will increase to 800°C, and the yielding strength and tensile strength will in turn be reduced by 90% or more. In addition, when the temperature of steel reaches a certain level, the mechanical behavior of the steel is altered by different fire temperatures and different methods of cooling .…”

A Study on Metallographic Microstructure of Steel Materials Subjected to Fire

“…When the temperature of an iron material reaches 550℃, the yield strength will reduce to about 60%, and 50% at 600℃. Based on the standard temperature curve of ASTM E 119 and ISO 834 [2] , when being heated for 20 minutes and the temperature of the furnace is raised to 800 ℃, the yield strength and elastic modulus of iron material will drop to below 10% of the original. In addition, when an iron material is heated to a certain temperature, the heating temperature and cooling mode will affect the mechanical behavior of iron materials to varying degrees [3].…”