The present research examines experimentally the performance of a new type of full-culm
bamboo to steel bolted connection under monotonic axial loading. The examined culms
are of the Kao Jue (Bambusa pervariabilis) bamboo species. The study characterizes the
performance of the proposed bamboo to steel connections in terms of failure modes, load-carrying
capacity and ductility. It specifically examines the influence on the mechanical
behavior of (a) the end-length (i.e. the distance between bamboo culm-end and outer
bolt-hole); (b) the transverse confinement provided by hose-clamps, and (c) the grouted
cement mortar added within the connection zones. The findings reveal that hose-clamps
effectively resist the brittle splitting behavior observed in plain bamboo to steel - bolted
connections. Combined with adequate end-lengths the connections achieve remarkable
gains in strength and ductility. The results also show that the mortar infill results to
connections of higher strength, but often at the cost of reduced ductility, compared to
the pertinent hollow-section connections with hose clamps. Importantly, the analytically
estimated yield loads of the examined connections using the European Yield Model are
in good agreement with the experimentally determined values.
This study experimentally investigates the axial response of bamboo to steel connections
under quasi-static reversed cyclic loading. It examines three different connection
configurations: (Type A) plain bolted; (Type B) transversely confined by hose-clamps;
(Type C) transversely confined by hose-clamps and infilled with cement mortar. The
study specifically evaluates the effects of loading history in terms of strength degradation, pinching and dissipated energy, and recommends equivalent viscous damping coefficients.
In general, the Type B and C connections are superior to Type A; they develop higher
strength, possess ductile failure modes and dissipate more hysteretic energy. Compared to
the monotonic response however, their cyclic performance is limited by early bolt-fracture.
Nevertheless, the examined connections show promise towards a capacity-based design as
the ductile components (i.e., the bolts) fail before the brittle components (i.e., the culms).
All members are composed of pairs of Bambusa pervariabilis (Kao Jue) bamboo culms.
This study presents a first attempt towards rational design of bamboo multi-culm axial
members with dowel-type connections. Specifically, it implements an original combination
of grading, use of multiple culms, and capacity design principles, to manage the natural
variability of bamboo culms and establish a reliable ductile failure. In this context, the
study also calibrates the pertinent over-strength factors needed for achieving capacity-based
design. The proposed axial members display high ductility and predictability owing
to dowel yielding before the other components, i.e., the steel gusset plates and the bamboo
culms fail. Furthermore, arranging bolts along two perpendicular planes of the circular
cross-section of bamboo culms increases efficiency, and offers notable gains in strength over
single plane bolt configuration. The characteristic values of average material/geometric
properties of multi-culm members estimated from single-culm material tests can predict
the experimental 5th percentile yielding of dowel connections with accuracy. Overall,
the proposed approach results in reliable multi-culm bamboo axial members and shows
promise towards a rational engineered design of bamboo structures.
This study examines experimentally and numerically the performance of the improved
version of full-scale bamboo truss footbridge. The truss is built of multi-culm bamboo
axial members with bolted steel connections, joined together via steel gusset plates. With
the aid of existing and new experimental results, the study first develops a bilinear model
that approximates the non-linear force-displacement response of multi-culm bamboo axial
members. It then establishes non-linear simulations of the truss structure under vertical
loading, accounting for the variability in geometry of bamboo culms and in yield capacity
of the bolted connections. Findings reveal, the proposed numerical simulations return
realistic force-displacement response of the truss structure. The axial deformation of
truss members is mostly due to bolt deformation and embedment, since the bamboo culms
are significantly stiffer than the bolted connections. The simulated yielding and damage modes occur at similar locations in the truss structure as those observed experimentally.
However, the simulated sequence of damage modes is effected by the natural variability
of bamboo culms. Overall, the developed simulations are promising. It is possible to
predict via simulations, the non-linear response of the bamboo footbridge, after testing
and modelling the behavior of its structural members.
This study investigates the effect of use of multiple bamboo culms and grading on
the variability of bamboo culms. Specifically through Monte Carlo simulations, it estimates
the total member capacity of multi-culm members using statistics from single-culm
members. Findings reveal, the variability reduces with the increase in the number of
culms for all examined properties. The numerically predicted trend agrees well with the
analytical inverse square root function obtained from Statistics. On the other hand, grading
alters the distribution and reduces the variability of only those properties that are
well-correlated to the indicating property. Overall, examined methods are effective in
managing the natural variability of bamboo culms.
Author’s keywords: bamboo structures, full-culm bamboo, round bamboo, bolted connection,
dowel-type connection, capacity design, managing variability, bamboo connections,
non-linear analysis
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