C. ZHAO et al.: THE MECHANICAL BEHAVIOUR OF NEW LONG-SPAN HOLLOW-CORE ROOFS ...
311–318
THE MECHANICAL BEHAVIOUR OF NEW LONG-SPAN
HOLLOW-CORE ROOFS BASED ON ALUMINUM ALLOY
HONEYCOMB PANELS
MEHANSKO OBNA[ANJE NOVIH STREH Z VOTLIMI JEDRI IZ
SATASTIH PANELOV ZA VELIKE RAZPONE, IZDELANIH NA
OSNOVI ALUMINIJEVIH ZLITIN
Caiqi Zhao, Jun Ma, Shengchen Du
*
Key Laboratory of Concrete and Prestressed Concrete Structure, Ministry of Education, School of Civil Engineering, Southeast University, 2#,
Southeast University Road, Nanjing 210096, China
Prejem rokopisa – received: 2018-04-15; sprejem za objavo – accepted for publication: 2018-12-06
doi: 10.17222/mit.2018.075
This article proposes a new type of spatial structure that is based on the principle of an aviation structure skin force bearing. The
structure consists of honeycomb panels and specialized connecting pieces to spatially combine the honeycomb panels and form
a novel skeleton-free hollow-core roof system (referred to as a "honeycomb panel structural system" (HPSS)). To evaluate the
stitching results of the new structure, its connection performance, failure mechanism and limiting load were examined, and the
full-scale samples that were designed and manufactured from two sets of HPSS were employed to conduct the experimental
research. The results indicated that the new structure has a high spatial stiffness and loading capacity. The failure mode of the
two test specimens comprises the shear damage of the connector and the buckling failure of the honeycomb panel. The existing
rectangular sandwiched honeycomb panel buckling theory cannot correctly reflect the plastic deformation or failure of the
sandwiched material, this paper obtained the analysis method for the honeycomb panel buckling characteristic value that is
consistent with practical conditions. Using different simulation methods, the comparative analysis results revealed that the
finite-element coupling method proposed in this paper can adequately simulate the actual operating state of the connector
between two honeycomb panels. This method is feasible, highly efficient, and provides a theoretical basis for future revision of
the design rules for this new type of spatial structure.
Keywords: long-span hollow-core roof, HPSS, connection performance, full-scale test
Avtorji predlagajo uporabo novega tipa prostorske strukture, ki temelji na strukturah, uporabljenih v aviaciji za izdelavo nosilnih
delov trupa in kril letal. Strukture so sestavljene iz panelov v obliki satovja in specialnih veznih delov (spojk), ki prostorsko
kombinirajo panele v nove oblike stre{nih konstrukcij, okraj{ano imenovane HPSS (angl.: Honeycomb Panel Structural
System). Avtorji so raziskovali razli~ne oblike novih struktur, njihove vezavne lastnosti, mehanizme po{kodb in poru{itve na
vzorcih naravne velikosti, ki so bili oblikovani in izdelani iz dveh setov HPSS. Eksperimentalni rezultati so pokazali, da imajo
nove strukture veliko prostorsko togost in nosilnost. Na~in poru{itve dveh izdelanih vzorcev obsega stri`no deformacijo spojk
(veznih vijakov) in po{kodbe zaradi uklona panelnega satovja. Uklonska deformacijska teorija ne more popolnoma opisati
dejanske plasti~ne deformacije pri~ujo~ega pravokotnega sendvi~-satastega panela oziroma njegove kon~ne poru{itve. Na
osnovi analiti~ne metode so avtorji dolo~ili karakteristi~ne vrednosti uklona panelnega satovja, ki se ujemajo z dejanskimi
pogoji. Avtorji so z uporabo razli~nih simulacijskih metod in rezultatov primerjalne analize odkrili, da predlagana kombinirana
metoda na osnovi kon~nih elementov ustrezno simulira dejansko operativno stanje povezave med dvema izbranima satastima
paneloma. Metoda je izvedljiva, visoko u~inkovita in podaja teoreti~ne osnove za revizijo zakonov oblikovanja tega novega tipa
prostorskih struktur.
Klju~ne besede: strehe z votlimi jedri za velike razpone, HPSS, u~inek vezave, preizkusi v naravni velikosti.
1 INTRODUCTION
The honeycomb structure that bees create is a very
reasonable spatial structure.
1–9
A composite aluminium
alloy honeycomb panel (the aluminium honeycomb core
that is sandwiched between the upper layer and the lower
layer of aluminium alloy sheets) has the advantages of
light weight, high stiffness, and noise and heat insula-
tion.
10–14
The panel is a typical representative of a high-
performance sheet material; it is extensively employed in
aviation, high-speed trains, ships and other fields.
15–18
This article presents a new type of spatial structure
that consists of honeycomb panels, i.e., the use of spe-
cialized connectors for an aluminum honeycomb panel
space assembly to construct a "novel, skeleton-free,
hollow-core, roof system" that does not have any load-
bearing rods
19
(referred to as a "honeycomb panel struc-
tural system" (HPSS)). The basic configuration of the
system is equivalent to an enlarged honeycomb panel, as
shown in Figure 1a. Studies have shown that
20–22
this
novel roof system combines load bearing and enveloping
into one body that is lightweight and has high stiffness
and excellent seismic performance as well as favourable
constructional and physical properties. In single-floor
industrial plant buildings of various span lengths (Figure
Materiali in tehnologije / Materials and technology 53 (2019) 3, 311–318 311
UDK 620.1:669.715:692.4 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 53(3)311(2019)
*Corresponding author e-mail:
dushengchen@hotmail.com

1b), the HPSS is especially suitable for long-span roof
structures, such as gravity-sensitive gymnasiums and air-
plane hangars (Figure 1c), which demonstrates broad
application prospects.
In the study of aluminium alloy lattice shells, Wang
Hong et al.
23
analysed the stability of a Schwieder-type
aluminium alloy lattice shell with a 40-m span under
different loads in detail. All these results showed that
destabilization was the main failure mode of the shell
structure. Using a single-layer K8 spherical lattice shell
structure as an example, Gui Guoqing et al.
24
used a
numerical simulation to analyse the geometric nonlinear
stability of an aluminium alloy lattice shell. They dis-
cussed the influence of the vector-to-span ratio, the load
distribution and the supporting condition on the stable
bearing capacity of the lattice shell. Hongbo Liu et al.
25
analysed with a nonlinear finite method to clarify the
stability performance of aluminium-alloy single-layer
latticed shell. The suggested values of the rise/span ratio
and the initial imperfection were presented. Sugizaki et
al.
26
tested four single-layer aluminium alloy spherical
lattices using reduced-scale models. They studied the
effects of three factors on the steady bearing capacity.
The influence of the nodal domain was taken into
account in the finite-element analysis.
27
Xiaonong Guo et
al.
28
investigated the resistance of aluminium alloy gusset
joint plates. Zechao Zhang et al.
29
analysed the perform-
ance of an aluminium alloy single-layer latticed shell.
With the geometrical nonlinear finite-element method,
the stability coefficient and the weak parts of the
structure were obtained considering the initial imper-
fections and the material nonlinearity.
In the study of the honeycomb structure’s stability,
Attard and Hunt
30
considered the shear deformation of
the panel and the core honeycomb layer. Using piecewise
first-order beam theory, they analyzed the overall buckl-
ing of the honeycomb structure. Bourada
11
and Tounsi et
al.
12
studied the instability of a honeycomb core with a
uniform wall thickness under uni- and bidirectional in-
plane compression and out-of-plane compression. Using
experimental studies and numerical simulations, A.
Boudjemai
31
and Amri et al.
32
studied the macroscopic
deformation and plastic instability of a honeycomb
structure with uniform wall thicknesses under unidirec-
tional in-plane compression.
It is obvious that the existing studies focus on the
aluminum-alloy lattice shell structure or the honeycomb
panel itself. Research on the new type of hollow-core
roof structure that is based on the aluminum alloy honey-
comb panel introduced in this paper is lacking. What are
the total stiffness and loading capacity of the new struc-
ture that is assembled by connecting as large number of
honeycomb panels? Existing differences between the
mechanical properties and the failure mechanisms of
similar spatial structures should be explored. Two sets of
full-scale hollow-box samples with a plane dimension of
1m×3mandastructural height of 300 mm were de-
signed and manufactured. The stitching connection
performance and ultimate bearing capacity of the new
structure were investigated to determine the connections
between the two panels, explore the failure mechanism
of the structure, and evaluate and verify the reliability of
the finite-element simulation methods between the
panels. The results provide design rules for a new spatial
structure with a theoretical basis for future revisions.
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312 Materiali in tehnologije / Materials and technology 53 (2019) 3, 311–318
Figure 2: Full-scale specimen overview: a) the total appearance, b) internal structure, c) geometrical dimensions
Figure 1: Typical form of the HPSS: a) flat honeycomb-panel roof system, b) door-frame type honeycomb-panel roof system, c) long-span
curved roof system

2 EXPERIMENTAL PART
2.1 The design and fabrication of the full-scale sample
Two sets of samples of the hollow-box type are em-
ployed. The plane dimensions of each sample are 1 m ×
3 m, the structural height of each sample is 300 mm, and
each sample is formed by stitching together 29 alumi-
num honeycomb panels with specialized connectors
(Figure 2). The plane dimensions of the top and bottom
plates (six panels for each plate) are 0.5m×1m;the
dimensions of the vertical side plate is 0.3m×1m(nine
panels), and the dimensions of the horizontal side plate is
0.3 m × 0.5 m (eight panels).
The thickness of the honeycomb panel used for the
sample construction was 10 mm, the thicknesses of the
upper and lower surfaces of the aluminum alloy sheet
was 1 mm, the thickness of the honeycomb core layer
was 8 mm, the n of the honeycomb core was 6 mm, and
the wall thickness was 0.05 mm. To facilitate the connec-
tion, a reinforced edge frame was set up around the peri-
phery of each honeycomb panel. Two box-type samples
(denoted as SJ1 and SJ2) were designed according to the
different types and number of bolts on the connectors.
Their plane dimensions and the specifications are
equivalent to the material utilized for the honeycomb
panel.
The connectors between the side-plates of specimen
SJ1 and the base of the plates and the connectors bet-
ween the bottom plates employed an ordinary bolt
connection with a diameter of 6 mm. The connectors
between the plate tops and the connectors between the
plate tops and the side-plates utilized a hexagonal head
self-drilling self-tapping screw connection with a dia-
meter of 4 mm. Three bolts were installed on each side
of the connector.
The connectors between the side-plates of specimen
SJ2 and the base plates, and the connectors between the
base plates employed high-strength bolts of 8.8 grade. In
the 1/3 segment of the mid-span, where the stress is
significant, five high-strength bolts with a diameter of
8 mm were added to each side of the connector. High-
strength, hexagonal, self-drilling, self-tapping bolts with
a diameter of 6 mm were used between the top plates.
High-strength bolts were constructed by specialized
electric tools to ensure a seamless tight fit between the
plates and the connectors.
2.2 Loading and testing methods
At the one-third points of the box-type specimen, two
concentrated loads were applied through the distribution
beam (Figure 3a). The hydraulic jack performed real-
time load monitoring and data acquisition through the
force sensors. Simple support conditions at both ends
were implemented by installing rollers and a backing
plate. To measure the bearing capacity of a specimen and
the displacement and strain distribution of a honeycomb
panel, a strain gauge rosette was attached to the front and
back of the longitudinal side-plates, the transversal side-
plates, top plate and the bottom plate of the box-type
specimen. The displacement sensor was installed near
the mid-span and supporting seat. The test site is shown
in Figure 3b.
3 RESULTS
3.1 Failure pattern of the specimen SJ1
In the third loading process, when the load was
increased to 10 kN, the specimen SJ1 began to produce a
sound. With an increase in load to 12 kN, the pressure
sensor exhibited a sudden decrease in the load with a
bang, and the mid-span displacement became significant-
ly larger, which indicates that the specimen has reached
its limit. Since the bending moment and shearing force
have the largest value at 1/3 of the span, the connector
bolts on the bottom plate, under the action of the bending
moment, were vertically sheared across the sheet. For the
connectors on the side plates, due to the combined effect
of bending moment and shearing force, the bolt was
bi-directionally sheared along the direction of the span
and the height of the specimen. The connection bolt on
both sides, in the direction of the height initially exhi-
bited shearing failure, which caused a sudden increase in
the load on the connectors on the bottom plate, the
connection bolts were successively sheared, and the
specimen lost loading capacity and was declared a
failure (Figure 4a and 4b, the sheared bolts are marked
with red arrows).
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Materiali in tehnologije / Materials and technology 53 (2019) 3, 311–318 313
Figure 3: Measuring point layout and loading site: a) loading
diagram, b) the testing site

3.2 Failure pattern of the specimen SJ2
When the specimen SJ2 was loaded to 38 kN, the
honeycomb panel was significantly deformed, and the
local stress concentration of the specimen was evident.
As a result, the honeycomb core was extruded and de-
formed by the face plate, and local tensile cracking
occurred between the honeycomb core and the face plate.
When the load was increased to 40 kN, a slight
buckling deformation began to appear at the one-third
point of the top plate. When the load was increased to
48 kN, the buckling deformation of the specimen was
distinct, and depressed buckling occurred (Figure 4c).
As the load increased to 52 kN, the buckling deformation
on the plate top significantly expanded. At the occur-
rence of the depressed buckling, a protruded buckling
deformation also occurred at the side plates (Figure 4d).
When the load increased to 55.7 kN, the hydraulic
jack was persistently pressured, and the force sensor
exhibited a decrease in load, whereas the deflection in
the mid-span continued to increase, which indicates that
the specimen has reached its limit.
4 DISCUSSION
4.1 Analysis of experimental results
An ordinary bolt connection was employed between
the two plates of specimen SJ1; thus, the connection
bolts were sheared during the damage of the specimen.
At this point, the deformation of the aluminum-alloy
honeycomb-panel was not significant, and the ultimate
bearing capacity of the specimen SJ1 was only 12 KN.
There forecast prior to the damage was not distinct,
which revealed the typical characteristics of brittle
failure. Since the high-strength bolt connection was
employed between the plates of specimen SJ2, no
shearing failure occurred in all the bolts of the connector
until specimen failure. Under the action of a vertical
internal force, buckling deformation occurred on the top
plate in the pressure zone of the box-shaped specimen
until the honeycomb panel completely buckled and lost
stability. Specimen SJ2 had a maximum measured
ultimate bearing capacity of 55.7 KN, which was 4.64
times the ultimate bearing capacity of specimen SJ1, and
displayed evident characteristics of ductile buckling
damage.
The new hollow-core roof structure that was
assembled from honeycomb panels has a high total
stiffness and load-bearing capacity, which demonstrates
excellent structural performance. However, effective
measures must be taken to ensure that the connectors do
not precede the buckling damage of the honeycomb
panel and that the lightweight and high-strength proper-
ties of the honeycomb panel can be fully applied to
realize the high load-bearing capacity of the proposed
structure.
The experimental results also revealed that the
mid-span deflections of the two specimens differ by only
1.4 mm under the ultimate load, which indicates that the
total stiffnesses of the two specimens were relatively
close. However, the ultimate bearing capacity of the two
specimens varied significantly. When specimen SJ1 was
damaged prior to the buckling of the honeycomb panel in
the pressure zone, the load-bearing capacity was lost due
to the insufficient anti-shearing strength of the bolt on
the connector. The advantages of the light weight and
high strength of the honeycomb panel cannot be fully
utilized. The connection performance of the connectors
has a critical role in the novel structure.
4.2 Finite-element simulation and theoretical analysis
of the specimen
4.2.1 Finite-element analysis
When applying the finite-element method to the
structural analysis of a new prefabricated honeycomb-
panel hollow-core roof, the following two issues must be
addressed: (1) the reasonable equivalency of the honey-
comb-panel; and (2) the reasonable simulation method
for the connectors between honeycomb panels. Due to
the complex internal structure of an aluminum honey-
comb panel and the lack of a honeycomb cell library in
existing software, if the interior of the honeycomb core is
also divided into subunits in the design (Figure 5), then
proceeding with the analysis will be difficult due to the
vast number of cells. Prior to the finite-element analysis
of the specimen, the aluminum alloy honeycomb panel is
equivalent to the anisotropic plate in this paper according
to the honeycomb-panel theory (Figure 6).
The following three different simulation methods
were employed in this paper for the comparison and
analysis of the specimens:
C. ZHAO et al.: THE MECHANICAL BEHAVIOUR OF NEW LONG-SPAN HOLLOW-CORE ROOFS ...
314 Materiali in tehnologije / Materials and technology 53 (2019) 3, 311–318
Figure 4: Failure patterns of specimen: a) the bolts on the side plates were sheared, b) the bolts on the bottom plate were sheared, c) compressive
buckling deformation of the top plate, d) deformation on the side plates

(1) Fully coordinated finite-element method. Due to
the approximate application of the fully coordinated
method, the calculation model cannot fully reflect the
actual connections between the panels. Therefore, the
analysis results tend to have large deviations with low
accuracy.
(2) Connection unit method. The method requires
specialized experiments or many calculation trials to
obtain reasonable stiffness parameters of the connection
unit.
(3) Finite-element coupling method. Due to nume-
rous connectors in the actual structure, refining the
model for each connector (including the bolts on the
connectors) will generate a large workload of modeling
and cell division, and the computation time will multiply,
which significantly reduces the efficiency of the struc-
tural analysis. Therefore, if a finite-element connection
method that approximates the simulation of the connec-
tion performance is utilized, then the time of structural
analysis will be substantially reduced, and the computa-
tional efficiency can be improved. Considering the
characteristics of the intermittent connections of the
connectors in the honeycomb-panel structure, and con-
sidering that the connectors were maintained in contact
with each other during the loading process, this paper
presents the degree of freedom coupling method to
approximate and replace the connector contact. The
analysis results are displayed in Table 1.
As shown in Table 1, the modeling of the fully
coordinated finite-element method is the simplest model;
however, because the error is large, this method cannot
be chosen. Although the error from the connection unit
method is not large, it requires many calculation trials
and experiments prior to the structural analysis to deter-
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Materiali in tehnologije / Materials and technology 53 (2019) ..., 311–318 315
Figure 6: Analysis model of the box-type specimen
Figure 5: Refinement model of the honeycomb core
Table 1: Computation results of specimen SJ2 for different connection simulation methods
Parameter Test value E
Fully coordinated
finite-element method
Finite-element coupling
method
Connection unit method
Calculation
value F 1
Error
D
1
Calculation
value F
2
Error
D
2
Calculation
value F
3
Error
D
Deflection / mm 8.70 6.28 27.8 % 8.15 6.32 % 7.67 11.8 %
plate stress /MPa 23.17 18.65 19.5 % 25.05 –8.1 % 26.01 –12.3 %
Note: D1 = (E-F1)/E; D2 = (E-F2)/E; D3 = (E-F3)/E
0

mine the reasonable stiffness parameters of connection
unit. Therefore, it is not suitable for analysis and the
design of large engineering projects. The finite-element
coupling method generated the smallest error; building
the coupling set in the modeling stage is convenient,
which satisfies the requirements of general engineering
accuracy.
4.2.2 Theoretical analysis of ultimate bearing capacity
When specimen SJ2 failed, the experimental state
indicated that external buckling occurred on the top plate
of the box-type specimen, where the pressure zone
exists, and the conversion stress on the top plate was
only 40 MPa at this point, which was significantly less
than the strength limit of the aluminum honeycomb-
panel; that is, the buckling of the sheet occurred prior to
the strength failure. Therefore, research on the stability
of a honeycomb panel under the action of internal
vertical pressure is crucial for the analysis of the ultimate
bearing capacity of a specimen.
Using the top plate of a honeycomb panel that is in
the pressure zone of a box-type specimen, as an example,
the buckling bearing capacity of a four-side simply
supported honeycomb sandwich panel was analysed with
respect to the lateral uniform load.
33
The plane dimen-
sion of this sheet is1m×0 . 5m ,t h ethickness is
h = 10 mm, and the effect of the uniform load is on the
short edge. Substituting the relevant parameters of the
honeycomb panel into the following formula:
p
D
b
m
mm
=
+
++
π
2
2
22
22
1
1
()
()
   
  
 In the equation, D is the buckling stiffness; b is the
plate width; b is the length-width ratio of the plate; and
m, d
1
, and d
2
are the undetermined constants.
When m = 2, the minimum value of 413.3 N/mm was
chosen for p after the calculation trial. Therefore, the
theoretical solution of the buckling bearing capacity of
the honeycomb panel is P
cr
= 413.3 N/mm × 500 mm =
206.65 kN. The theoretical solution obtained from the
analysis of the honeycomb panel and the finite-element
results given by the three equivalent theories are listed in
Table 2.
The analysis results indicated that both the sand-
wiched-core-plate theory and the honeycomb-plate
theory do not substantially differ from the theoretical
solutions in solving the buckling characteristic values of
the honeycomb panel. According to the Reissner theory,
the metal panel primarily bears the tensile and compres-
sive stress of the honeycomb panel. As shown in Table
2, the reduced compressive stress on the upper and lower
plates of the honeycomb panel under the action of the
buckling load are (206.65, 188.42, 223.18, and 229.35)
MPa. Regardless of the theoretical solutions or finite-ele-
ment solutions, the compressive stresses of the upper and
lower plates have exceeded the ultimate bearing strength
of the aluminum alloy.
Although the buckling characteristic values can be
obtained by an analysis based on the theory of sand-
wiched honeycomb core buckling, the finite-element
analysis and stress calculation of the aluminum alloy
honeycomb panels indicate that the strength of the alu-
minum alloy sheet buckled prior to the buckling of the
honeycomb panel. This phenomenon indicated that the
geometric defects of the sheet material and the premature
failure of the internal core material have a significant
influence on the load-bearing capacity of a metal honey-
comb panel.
The middle core layer of a honeycomb panel is com-
posed of thick and soft aluminum foil. The application of
the honeycomb core buckling theory and the three
equivalent theoretical finite-element analyses did not
consider whether the core material is plasticized or in
failure, or whether the material property change was
caused by the collapse of the core (that is, the buckling
analysis was only performed for the entire sheet without
considering the nonlinearity of the material). This
finding does not correspond to the practical situation.
When the face plate is combined with the core to
form the metal honeycomb panel, the bearing capacity of
the entire panel is increased to a certain extent but will
not reach the value that is listed in Table 2. In the finite-
element analysis, amendments are necessary. First, the
upper limit value of the internal and external failure of
the honeycomb must be determined. The failure refers to
the maximum load value sustained by the honeycomb
prior to collapse. According to the upper limit formula of
the plastic collapse stress presented by Gibson et al.,
25
the upper limit value of the plastic collapse stresses in all
directions are  ypl
= 0.0053 MPa,  xypl
= 0.0017 MPa,
 xzpl
= 0.250 MPa, and  yzpl
= 0.217 MPa (the subscript
refers to the direction of the stress). The finite-element
analysis of the buckling load for the honeycomb panel
with the plate dimension of 1 m × 0.5 m was performed.
The stress failure criterion was used to control the stress
change of the aluminum alloy panel and the honeycomb
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316 Materiali in tehnologije / Materials and technology 53 (2019) 3, 311–318
Table 2: Comparison of the theoretical solution and the finite-element solution of a honeycomb plate (1 m × 0.5 m) for buckling bearing capacity
Parameter
Theoretical
solution (L)
Sandwich core plate theory Honeycomb plate theory Equivalent plate theory
Calculation
value T 1
Error
D
4
Calculation
value T
2
Error
D
5
Calculation
value T
3
Error
D
6
P
cr
/KN 206.65 188.42 8.8 % 223.18 –8.0 % 229.35 –11.0 %
Note: D4 = (L-T1)/L; D5 = (L-T2)/L; D6 = (L–T3)/L.

equivalent core to solve the internal buckling load of the
actual honeycomb core sheet.
When the load on the honeycomb core aluminum foil
reaches the upper collapse stress limit of 0.0053 MPa,
the support to the face plate is lost, which causes buckl-
ing of the honeycomb panel and the entire panel. After
the collapse of the honeycomb core, the compressive
stress on the metal face plate is 49.46 MPa in the
x-direction. This stress can be obtained after conversion,
where the load was P = 30.23 kN; then, the ultimate bear-
ing capacity of the specimen was P
cr1
=2 P = 60.46 kN.
This value is approximately 29.26 % of the theoretical
honeycomb panel buckling value (206.65 kN); compared
with the tested value of P
cr2
= 55.69 kN, the difference is
7.89 %.
These analysis results indicate that the rectangular
sandwiched honeycomb plate buckling theory cannot
correctly reflect the plastic change or failure of the sand-
wiched core material or the influence of the sandwiched
core material property change on the face plate load.
Only the total honeycomb panel working performance
was considered, which is not consistent with a practical
situation. After considering the material property of the
honeycomb core, the honeycomb panel internal surface
buckling controlled by the upper limit of honeycomb
collapse stress given by Gibson et al.
34
can yield honey-
comb panel internal surface buckling characteristic
values that are relatively consistent with a practical
situation.
When calculating the ultimate bearing capacity of a
honeycomb-panel structure, the buckling performance of
the honeycomb panel must be analyzed and calculated
under compression to determine whether the controlling
factor is strength or stability when the structure enters
plastic deformation and reaches the ultimate state. If the
controlling factor is stability, then the honeycomb panel
buckling performance will be analyzed by considering
the influence of internal honeycomb collapse on panel
buckling performance.
5 CONCLUSIONS
This paper proposes a new type of hollow-core roof
system (referred to as a HPSS) that comprises the
assembly of aluminum honeycomb panels solely via
sheet stitching using specialized connectors. The con-
nection performance and ultimate bearing capacity were
experimentally analyzed by the finite-element theory.
The following conclusions were obtained:
(1) A novel prefabricated hollow-core roof structure
has a high spatial stiffness and ultimate bearing capacity,
which reveals the structural characteristics of light
weight and high strength. A comparison of the test re-
sults indicates that effective measures are necessary to
ensure that the connection components do not fail before
honeycomb panel buckling or strength failure and to
fully explore the light weight and high strength characte-
ristics of the honeycomb panel to ensure adequate load
capacity.
(2) The failure mode of the two test specimens com-
prises the shear damage of the connecting components
and the buckling failure of the honeycomb panel inner
surface. The connection bolts had been sheared off prior
to the failure of specimen 1, whereas the honeycomb
panel did not exhibit distinct deformation; the specimen
exhibited typical brittle failure characteristics. Since
specimen 2 was connected by high-strength bolts, the
ultimate bearing capacity was significantly higher than
the ultimate bearing capacity of specimen 1. The connec-
tion components were intact when the panel failure
occurred; the top plate at the compression zone had sig-
nificant compressive buckling deformation; and the
specimen exhibited reasonable ductile buckling failure
characteristics. Therefore, the connection performance of
the connection components is critical to the load per-
formance of the proposed novel prefabricated structures.
(3) The study results for the honeycomb panel inner
surface buckling performance indicate that the existing
rectangular sandwiched honeycomb panel buckling
theory cannot correctly reflect the plastic deformation or
failure of the sandwiched material or the conducive
influence of the sandwiched material on plate-buckling
resistance. These results are not consistent with the prac-
tical working state of the honeycomb panels. By consi-
dering the honeycomb core material’s properties and
controlling the honeycomb panel inner surface buckling
with the ultimate honeycomb collapse stress, this paper
obtained an analysis method for the honeycomb panel
inner surface buckling characteristic value that is consis-
tent with practical conditions.
(4) Rational simulation of the connections between
honeycomb panel materials is the key to the design of
this type of prefabricated honeycomb panel structure.
Using different numerical simulation methods, the com-
parative results of the finite-element analysis for the
box-type specimen indicated that the coupled finite-ele-
ment method proposed in this paper can adequately
simulate the practical working state of the connection
components between the honeycomb panels. This me-
thod is feasible, highly efficient, and provides a theore-
tical basis for future revision of the design rules for this
new type of spatial structure.
Acknowledgments
This study was supported by the Natural Science
Foundation of China under grant no. 51578136.
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