Abstract
With the increasing use of bolted joints in composite structures, it becomes crucial to predict the failure load of these
joints under out-of-plane loads. The present study explores the pull-through failure mode of bolted joints in composite structures
through both numerical and experimental methods. The sandwich specimens were tested using the ASTM D7332. In the
numerical study, a user-defined subroutine was developed to investigate the failure modes and mechanisms, as well as damage
propagation in sandwich structures and laminated composites progressively. To reduce the dependence of the standard test
outputs on geometrical variables, a novel parameter called nominal pull-through strength (SPT) has been defined for laminated
composites. This parameter allows the results of structural tests on specimens with standard dimensions to be applied to joints of
various sizes in practical applications. Additionally, a simplified procedure for designing composite bolted joints in the pull
through mode has been proposed using the SPT parameter. SPT results have been evaluated statistically to find the probability
distribution function and determine the strength corresponding to each confidence level.
Abstract
The Elliptical-head one-side bolt (EOB) serves as a typical representative of the third generation of blind bolts,
favored by researchers for its simple construction and impressive installation efficiency. The tensile performance of EOBs bolted
T-stub connections was investigated in this paper through numerical simulation and theoretical analysis, which forms the basis
for calculating the bending capacity of beam-column joints using the component method in Eurocode 3. Distinct parameters
associated with EOB connections were thoroughly examined in this paper, including the layouts of bolt holes, the installation
gap between bolt and hole, the rotation deviation of bolt shank, and the bolt offset within the hole. The research results indicated
that a total of 5 yield line patterns emerged on the T-stub flange, which are significantly influenced by the bolt end distance and
flange width. The Finite element (FE) results demonstrate that the reduction in bearing capacity for the connections bolted by
EOBs is within 10% compared to those using Conventional high-strength bolts (CHBs). Adopting the vertical layout for bolt
holes and avoiding bolt offset within the holes are approaches to achieving optimal bearing capacity for the connections. A bolt
rotation deviation within 20° and bolt holes with rough assembly accuracy serve as guarantees for improving installation
efficiency. The analysis model and theoretical equations, modified based on Eurocode 3 for predicting the yield strength of
EOBs bolted T-stub connections, have been validated through FE models and can be further extended for broader application.
Key Words
design method; Elliptical-head one-side bolt (EOB); slotted bolt hole; T-stub connection; yield line pattern
Address
Lele Sun:Yantai Research Institute, Harbin Engineering University, Yantai, Shandong Province, 264000, China
Le Liu:School of Civil Engineering, Shandong University, Jinan, Shandong Province, 250061, China
Jin Zhang:School of Civil Engineering, Shandong University, Jinan, Shandong Province, 250061, China
Peijun Wang:School of Civil Engineering, Shandong University, Jinan, Shandong Province, 250061, China
Gangling Hou:Yantai Research Institute, Harbin Engineering University, Yantai, Shandong Province, 264000, China
Min He:Yantai Research Institute, Harbin Engineering University, Yantai, Shandong Province, 264000, China
Abstract
Seismic vulnerability in aging low-ductility reinforced concrete (RC) frames poses significant risks in earthquake
prone regions due to inadequate lateral load resistance and noncompliance with modern seismic codes. This study investigates
the potential of thin steel infill plates as a practical alternative to enhance the seismic performance of low-ductility RC frames.
Experimental testing and numerical modeling were conducted to assess the effects of different infill plate-to-boundary frame
connection configurations on lateral strength, stiffness, and energy dissipation. Three RC frame specimens were tested under
reversed cyclic lateral loads: one bare frame as a baseline and two frames incorporating thin steel infill plates with different
connection schemes. In one configuration, the steel plate was fully integrated with the frame; in the other, it was attached only to
the beam and foundation. Numerical models were developed in OpenSees, incorporating bond-slip mechanisms and the shear
behavior of beams and columns. Experimental and numerical results, demonstrating strong correlation, indicate that the
incorporation of steel plates into low-ductility RC frames significantly enhances their ultimate strength. The presence of steel
infill plates notably improved the initial stiffness, energy dissipation capacity, and lateral strength of the frames. Furthermore, no
abrupt strength degradation was observed throughout the testing, despite the development of shear cracks in the beams and
columns of the specimens with infill plates, underscoring the effectiveness of the steel plates in mitigating seismic
vulnerabilities.
Abstract
The four-side connected buckling restrained steel plate shear wall (FBRW) exhibits robust mechanical properties,
including a high lateral load-bearing capacity and excellent stiffness, as well as effective energy dissipation. However, there is an
inherent vulnerability due to the gap between the restraining panels and the boundary elements. This gap forms an unrestrained
area in the inner steel plate, which is mechanically inferior to the areas confined by restraining panels. Consequently, damage
typically manifests first in these unrestrained areas, particularly at the corners of the inner steel plate. To address this limitation,
this paper introduced a modified design—namely, the four-side connected buckling restrained steel plate shear wall with
staggered holes (SHBRW). In this innovative design, staggered holes were strategically positioned in the restrained regions of
the inner steel plate. These perforations served to intentionally weaken those areas, thereby concentrating plastic strain within
them. Moreover, the staggered holes oriented the inner steel plate into multiple strips aligned at 45 degrees, which aligns well
with the principal stress direction in FBRW. This alignment enhanced the load-bearing efficiency of SHBRW. To rigorously
assess the mechanical performance of SHBRW, finite element analysis was conducted. This analysis accounted for the
distribution of plastic strain within the inner steel plate, as well as the internal forces exerted on the boundary elements.
Subsequently, an optimal hole layout—comprising both hole spacing and diameter—was determined. Finally, theoretical
equations for calculating the initial stiffness and yield capacity of SHBRW were derived to fulfill the demands of both
performance evaluation and structural design. A comparison between these theoretical calculations and the results of the finite
element analysis revealed a high degree of concordance, affirming the utility and accuracy of the theoretical equations for
practical applications.
Address
Wen-yang Liu:1)College of Civil Engineering and Water Conservancy, Heilongjiang Bayi Agricultural University, Daqing, China
2)Key Laboratory of Agricultural Machinery Intelligent Equipment of Heilongjiang Province, Daqing, China
Huan-huan Li:College of Landscape Architecture, Shangqiu University, Shangqiu, China
Qi-peng Dai:College of software, Harbin Institute of Information Technology, Harbin, China
Rong-hua Zhang:College of Civil Engineering and Water Conservancy, Heilongjiang Bayi Agricultural University, Daqing, China
Na Bai:College of Civil Engineering and Water Conservancy, Heilongjiang Bayi Agricultural University, Daqing, China
Abstract
This paper presents the main results of an experimental program aimed at the investigation of the behaviour of
galvanized steel members and the characterization of its surface emissivity starting from the temperatures measured during
small-scale furnace tests. The results confirm the beneficial effect of galvanization on slowing down the heating, indeed, the
temperatures in the hot dip galvanized specimens were found lower than the not galvanized ones. Tests results also confirm that
the emissivity depends on steel temperature, in line with the new Eurocode. Considering the effect of hot-dip galvanizing by
implementing a variable emissivity, allows for the extension of calculation methodologies for the fire resistance of steel
elements, even for galvanized steel, using both simplified and advanced methods. Therefore, this paper presents results of
several implementations of the Eurocode design methods for assessing the structural fire resistance of galvanised steel elements.
In this framework, the simplified "nomogram procedure" approach, typically used for steel members, has been adjusted by
authors for galvanized steel elements. Finally, the results of advanced thermo-mechanical analyses of steel single story frames,
which were carried out to assess the effect of the galvanization on the whole structural fire behaviour were reported. This latter
shows that, also in this case, if the required performance level is not particularly severe, the galvanization allows to guarantee the
fire requirements, saving the application of fire protection.
Key Words
electrical furnace; experimental tests; fire resistance; Galvanization; steel elements; surface emissivity
Address
Margherita Autiero:Department of Structures for Engineering and Architecture, Di. St., University of Naples Federico II Via Claudio n. 21, 80125, Naples, Italy
Donatella de Silva:Department of Structures for Engineering and Architecture, Di. St., University of Naples Federico II Via Claudio n. 21, 80125, Naples, Italy
Antonio Bilotta:Department of Structures for Engineering and Architecture, Di. St., University of Naples Federico II Via Claudio n. 21, 80125, Naples, Italy
Emidio Nigro:Department of Structures for Engineering and Architecture, Di. St., University of Naples Federico II Via Claudio n. 21, 80125, Naples, Italy
Abstract
Delamination in composite laminates is primarily caused by transverse tensile stress. However, experimental and
numerical studies have consistently shown that hybrid composite laminates, reinforced with thin-plies, exhibit greater strength
under static transverse tensile loads in comparison to reference conventional composite laminates. This study focuses on
analyzing the behavior of composite laminates reinforced by thin-ply, subjected to high-rate and impact transverse tensile
loading. A conventional composite, Texipreg HS 160 T700, and a thin-ply, NTPT-TP415, were selected for this investigation.
Hybrid laminates were created by integrating 25% thin-plies throughout the laminate's thickness. Subsequently, unidirectionally
stacked laminates were subjected to high-rate and impact transverse tensile loading. The experimental results showed a slight
increase in the transverse tensile strength of the hybrid laminate compared to the reference conventional composite under both
high-rate and impact-loading conditions. To delve into the microscale behavior of these configurations, a representative volume
element was analyzed using numerical methods, providing valuable insights into the studied setups.
Key Words
composite laminate; high-rate loading; impact loading; thin-ply
Address
Farin Ramezani:Instituto de Ciencia e Inovacao Em Engenharia Mecanica e Engenharia Industrial (INEGI, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal)
Ricardo J.C. Carbas:Departamento de Engenharia Mecanica, Faculdade de Engenharia (FEUP, Universidade Do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal)
Eduardo A.S. Marques:Departamento de Engenharia Mecanica, Faculdade de Engenharia (FEUP, Universidade Do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal)
Lucas F.M. da Silva:Departamento de Engenharia Mecanica, Faculdade de Engenharia (FEUP, Universidade Do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal)
