Abstract
This paper presents the experimental results of four full-scale coupling beams in which only horizontal reinforcements are placed, without diagonal reinforcements, with the aim to develop reinforcement details for coupling beams used in connecting side walls in a wall-slab structural system. Each coupling beam specimen was designed according to the deep-beam design procedure that does not use diagonal reinforcements and that is found in current standards. Two cases for basic deep-beam design specimens were investigated wherein (1) U-type reinforcement was added to prevent sliding shear failure of the joints and (2) horizontal intermediate reinforcements were placed. The coupling beam specimens were fabricated with a shear span-to-depth ratio (aspect ratio) of 1.68 and were connected to walls only by horizontal reinforcements, i.e., without diagonal reinforcement. The experimental results indicate that the strength of the beams was about 1.5 times the designed strength of a strut-and-tie model, which suggests that the model is available for predicting the strength of coupling beams with conventional reinforcement layouts such as horizontal and transverse reinforcement bars. The deformation capacity of these conventionally reinforced concrete coupling beams ranged from 1.48 to 3.47% in accordance with the reinforcement layouts of the beams. Therefore, this study found that the performance of conventionally reinforced concrete coupling beams with an aspect ratio of 1.68 can be controlled through the implementation of reinforcement details that include U-type reinforcement and the anchorage of intermediate horizontal bars.
Highlights
Structural walls can serve as an effective structural system to resist lateral loads, such as earthquakes or winds, in high-rise buildings
The study used reinforcement details for the connection between the beam and the wall as variables, based on reinforcement details required by current standards, to investigate the behavioral characteristics of coupling beams whose shear span-to-depth ratio is less than 2.0 and where only conventional reinforcement layouts are placed, i.e., without diagonal reinforcements
(1) Coupling beams whose shear span-to-depth ratio was 1.68 and which were connected to walls only by horizontal reinforcements, without diagonal reinforcement, showed strength that is about 1.5 times the design strength for a strut-and-tie model, indicating that proper design strength is possible using these construction details
Summary
Structural walls can serve as an effective structural system to resist lateral loads, such as earthquakes or winds, in high-rise buildings. Coupling beams that connect these walls, which behave independently at each floor, can improve the building’s lateral resistance capacity. The coupling beam should have the ability to resist the bending moment but should possess a certain deformation capacity because it plays a role in inducing the ductile behavior of the wall. In this regard, Eurocode 8 (2004) states that a coupling beam can be utilized as the beam in the moment-resistant frame only in those cases where it is Copyright Ó The Author(s) 2017.
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