Fatigue behaviour of timber-concrete composite connections and floor beams
In recent years. timber-concrete composite systems have become more widely used as a new construction technique for buildings and bridges. The main advantage is that the compressive strength of concrete is exploited through the use of composite action while timber beams are able to resist the tensil...
| Main Authors: | , , |
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| Format: | Article |
| Published: |
Elsevier
2013
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1016/j.engstruct.2013.08.042 http://dx.doi.org/10.1016/j.engstruct.2013.08.042 http://eprints.uthm.edu.my/5387/1/david_yeoh_eng_chuan_1_U.pdf |
| Summary: | In recent years. timber-concrete composite systems have become more widely used as a new construction
technique for buildings and bridges. The main advantage is that the compressive strength of concrete
is exploited through the use of composite action while timber beams are able to resist the tensile stresses.
The level of composite action. which can be achieved by the system. is dependent on the type of shear
connector used. There is a lack of knowledge. however, on the performance of these types of connections
when subjected to cyclic loading, which is typical for bridges. Testing was performed in the Structures
Laboratory of the University of Canterbury to analyse the fatigue behaviour of two types of timber-con-
Crete connections via push-out specimens, and two beam specimens representing strips of composite
floor with the same connection types. The two types of connection investigated were: (i) a rectangular
notch connection reinforced with a coach screw (also known as lag screw); and (ii) a connection with
toothed metal plates punched into laminated veneer lumber (LVL). The stiffness of the connection was
monitored throughout the cyclic loading along with the total amount of slip occurring between the concrete
and timber. After the application of 2 million cycles, the push-out and beam specimens were loaded
to failure in order to quantify their maximum strength. The strength of the rectangular notched connection
after cyclic loading was 0.95 times of the one without cyclic loading, while for the metal plate connection
was 0.60 times. For the metal plate connection. a continuous increase in slip was observed with
increased cycles possibly due to accumulated damage from repeated loading. The rectangular notch connection
displayed more resistance to changes in slip. strength and stiffness than the metal plate connection.
No obvious loss of stiffness was observed in the rectangular notch connected floor beams after
2 million cycles, and when tested to failure the stiffness was very similar to the same floor beam that
had not been cyclically loaded. The floor beam with metal plate connections did not perform well and
failed after 350.000 cycles. The loss pf strength, stiffness and composite action in this floor beam compared
to the one without cyclic loading was significant In this respect. the rectangular notch connection
system is recommended for use in bridge design as opposed to metal plate connections. |
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