Performance assessment of timber support system subjected to combined actions

Inductive coupling between two coils is becoming an important technique for wireless power and data transfer in near-field for a variety of applications such as wireless charging and passive (zero-power) sensors. We have previously employed a pair of printed spiral coils (PSC) to collect the physiological signals via our novel Wireless Resistive Analog Passive (WRAP) skin attachable sensors. The pair of PSCs and the circuit components have been optimized to maximize the probed biosignals where the mutual inductance (or coupling factor) was kept constant. However, the coils' relative positions in the wearables can vary in real-life scenarios, which makes the mutual inductance to change, compromising optimal results. To design a system with maximum robustness against these PSC alignment variations, the effects of primary coil size on the coupling factor variability to axial and lateral displacements are studied. We limited the maximum self-inductance to 5 µH and 7 µH for primary and secondary coils, respectively that ensures the results are not affected by the coils' self-inductance variation. Our simulation shows that larger primary coils create magnetic fields with reduced sensitivity to the coupling factor for lateral and axial displacements. The resultant coupling factor behavior indicates robust coil designs for applications where the axial and lateral displacements can occur in real-life.

Axial-flexural behaviour of concrete filled double skinned steel tubular (CFDST) composite column: Experimental investigations

Composite construction with steel and concrete has become a widespread solution in modern construction practices because of its inherent properties such as high strength-to-weight ratio, good corrosion resistance, and high stiffness. Concrete-filled fiber-reinforced polymer (FRP) steel double-skin tubular compression members as vertical load–carrying members in buildings helps in optimizing the advantages of three materials: steel, concrete, and FRP. This study investigates the axial compressive behavior of short, concrete-filled glass fiber–reinforced polymer (GFRP) steel double-skin tubular (GSDST) columns and concrete-filled GFRP tubular (CFFT) columns. Parameters such as the number of FRP layers, hollow section ratio (HSR), variation of diameter of the inner steel tube, and the angle of orientation of the fibers have been examined in this investigation. The experimental study was carried out by performing a monotonic axial compressive loading condition. Three different angles of fiber orientation, 0° along the hoop direction, 45°, and 0°/90° with respect to the axis of the column, were adopted in this study. The ultimate load-carrying capacity, axial displacement, axial and horizontal strains, and failure modes were observed. The experimental results indicate that the structural performance of GSDST columns is significantly influenced by GFRP tube thickness, inner steel-tube diameter, and fiber-orientation angle. Maximum displacement was observed in the specimens with high HSR, thus showing a ductile characteristic in the axial load-displacement behavior. The load-carrying ability of the specimens decreased as the HSR increased. The load-carrying capacity of the specimens increased with the increase in outer GFRP tube thickness. This study demonstrates that GFRP tubes can be used efficiently in the construction field as vertical load–carrying components by enhancing the axial behavior of FRP steel double-skin tubular columns.

This paper presents a streamlined methodology to assess the horizontal response of an embedded pile subjected to combined horizontal dynamic and axial static loads in a nonhomogeneous Pasternak medium. The stiffness matrix equations for the pile elements are formulated using the modified finite beam element method (FBEM), enabling a comprehensive consideration of factors such as the axial second-order effect of the pile (P-Δ effect), soil shear effect, and side friction on the pile. Utilizing the FBEM, the solutions for the pile’s lateral displacements and bending moments are derived while accounting for continuous pile–soil system boundary conditions. The accuracy of the FBEM is verified against existing solutions. Subsequently, a thorough parametric analysis is performed to investigate the influences of various properties of the pile, soil, and applied load on the pile’s horizontal vibration response. This study underscores the significant role of the shear effect exerted by the surrounding soil in restraining the lateral deformations and internal forces of the pile. In stratified soils, the horizontal performance of the pile is notably impacted by the properties of the surface soil. Reducing the strength of the surface soil results in a substantial increase in the pile’s bending moments and lateral displacements. Additionally, an increase in axial load at the pile head significantly affects the bending moments and lateral displacements due to the P-Δ effect. Moreover, the study reveals that the lateral displacements and bending moments of the pile exhibit an increase with the increases of the horizontal harmonic load amplitude H0 and a decrease with the increases in the dimensionless frequency a0 of the applied load.

A novel spiral confined angle-steel reinforced concrete (SCARC) column was developed in this study. A total of 16 specimens were prepared and tested (eight of them were tested under axial loading, the other eight were tested under eccentric loading). The failure processes and load-displacement relationships of specimens under axial and eccentric loads were examined, respectively. The load-carrying capacity and ductility were evaluated by parametric analysis. A calculation approach was developed to predict the axial and eccentric load-carrying capacity of these novel columns. Results showed that the spiral reinforcement provided enough confinement in SCARC columns under axial and low eccentric loads, but was not effective in that under high eccentric loads. The axial load-carrying capacity and ductility of SCARC columns were improved significantly due to the satisfactory confinement from spirals. The outer reinforcement and other construction measures were necessary for SCARC columns to prevent premature spalling of the concrete cover. The proposed calculation approach provided a reliable prediction of the load-carrying capacity of SCARC columns.

PurposeEarthquake tremors not only increase the chances of fire ignition but also hinder the fire-fighting efforts due to the damage to the lifelines of a city. Most of the international codes have independent recommendations for structural safety against earthquake and fire. However, the possibility of a multi-hazard event, such as fire following an earthquake is seldom addressed.Design/methodology/approachThis paper presents an experimental study of Reinforced Concrete (RC) columns in post-earthquake fire (PEF) conditions. An experimental approach is proposed that allows the testing of a column instead of a full structural frame. This approach allows us to control the loading and boundary conditions individually and facilitates the testing under a variety of these conditions. Also, it allows the structure to be tested until failure. The role of parameters, such as earthquake intensity, axial load ratio and the ductile detailing of the column on the earthquake damage and subsequently the fire performance of the structure, is studied in this research. Six RC column specimens are tested under a sequence of quasi-static earthquake loading, followed by combined fire and axial compression loading conditions.FindingsThe experiment results indicate that ductile detailed columns subjected to 4% or less lateral drift did not lose significant load-carrying capacity in fire conditions. A lateral drift of 6% caused significant damage to the columns and reduced the load-carrying capacity in fire conditions. The level of the axial load acting on the column at the time of earthquake loading was found to have a very significant effect on the extent of damage and reduction in column load capacity in fire conditions. The columns that were not detailed for a ductile behavior observed a more significant reduction in axial load carrying capacity in fire conditions.Research limitations/implicationsThis study is limited to columns of 230 mm size due to the limitations of the test setup. The applicability of these findings to larger column sections needs to be verified by developing a numerical analysis methodology and simulating other post-earthquake-fire tests available in the literature.Originality/valueThe experimental procedure proposed in this paper offers an alternative to the testing of a complete structural frame system for PEF behavior. In addition to the ease of conducting the tests, the procedure also allows much better control over the heating, structural loading and boundary conditions.

Dynamic finite element analysis of laminated beams with delamination cracks using contact-impact conditions

The performance of the fiber‐optic displacement sensor with beam‐through detection technique is investigated. The effects of lateral and axial displacements on the detected output voltage are investigated for various core's diameters of the sensor. The highest sensitivity is obtained at 0.0008 mV/μm for the lateral displacement with core's diameters for both transmitting and receiving fibers are fixed at 0.5 mm. At present, the widest linear range is obtained at 3195 μm for the axial displacement with 1.0 mm core's diameters for both fibers. The highest resolution of the 13 μm is obtained with the lateral displacement sensor with 0.5 mm core diameter. The sensor with the smaller core shows a better sensitivity and resolution with the expense of the smaller linear range. The beam‐through sensors have a simple design, high degree of sensitivity and dynamic range, and low cost. These make the sensors are useful for microdisplacement measurement in the hazardous region. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2038–2040, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24584

Mechanical performance of rock bolts under combined load conditions

This paper presents the behavior of A992 wide flange steel columns under fire loading. Experimental tests were conducted to investigate the structural-thermal response of steel columns subjected to axial loads and elevated temperatures. Two identical W14X53 specimens were tested under (i) non-standard fire loading to determine the axial load capacity at elevated temperature and (ii) standard fire loading to determine the buckling temperature of the axially loaded steel column. For the non-standard fire test (Test I), the monotonically increasing axial load was imposed on the steel column under steady-state heating condition. For the standard fire test (Test II), the steel column carrying the sustained axial load was tested under transient heating condition. The structural-thermal responses of steel columns observed in Test I and Test II were compared including column end rotations, lateral and axial displacements, and steel temperatures. The measured column buckling behaviors were also compared to those obtained by 3D finite element analyses. The results indicated that the end rotations and displacements of the steel column before buckling were affected by the sequence of applied loading. Both Test I and Test II provided the similar prediction of axial load capacity and buckling temperature of the steel columns.

Helicopter transmission shafts, as core components for power transmission, endure complex alternating loads during operation. In this study, a systematic investigation was conducted to address the fretting wear of the journal of the transmission shaft under complex loading conditions, involving theoretical modeling, numerical simulation, and experimental validation. First, the adhesive wear and abrasive wear coefficients of 9310 steel were obtained through a flat-rack wear test. Using ANSYS finite element software, an ALE mesh-adaptive technique was applied to simulate the contact stress and sliding distance on the journal contact surface under various operating conditions, including different rotational speeds, axial loads, and radial loads. The fretting wear volume of the journal was then calculated based on the Archard wear model. The results show that both contact stress and sliding distance increase with rising rotational speed, axial load, and radial load, with radial load having the most significant impact on both contact stress and sliding distance. A comparative experiment was conducted using a self-built fretting wear test rig for the journal, which validated the accuracy and applicability of the predictive model. The findings provide a reliable theoretical foundation and engineering methods for assessing and predicting the fretting wear of transmission shaft journals under complex loading conditions.

Tests on seismic and shear performance of RC shear walls under alternating axial tensile and compressive loads

To compare the biomechanical performance of adjunctive locking plating and double-loop cerclage wiring in feline femora implanted with Zurich cementless total hip replacement (THR) stems. Cadaveric biomechanical study. Paired femora (n = 32) from 16 feline cadavers. Two sequential studies were performed. First, femora implanted with Zurich cementless stems alone were compared with those stabilized by an adjunctive locking plate. Second, femora with locking plates were compared with those with cerclage wires. Constructs underwent cyclic axial and torsional loading followed by load-to-failure testing. Outcome measures included residual axial and torsional displacement, yield and ultimate forces and torques, energy absorption, and brittle failure frequency. Parameters were normalized to bone volume. The locking plate group demonstrated substantially reduced residual torsional displacement and a trend toward lower axial displacement compared with the stem-only group. Yield and ultimate failure strength did not differ. The cerclage group exhibited 36% greater ultimate axial displacement, 76% greater energy absorption, and 32% greater torsional displacement than the locking plate group. Normalization accentuated these differences. Cerclage wire fixation was associated with a lower frequency of brittle failure. Locking plates improved cyclic stability by reducing micromotion, while cerclage wires enhanced compliance and energy absorption under destructive loading. Neither method increased load to failure. Adjunctive plate or cerclage wire provided biomechanical advantages in femora implanted with Zurich cementless THR stems. Locking plates may support implant stability, whereas cerclage wiring improves energy dissipation under supraphysiologic loading. Adjunctive fixation strategies should be tailored to patient-specific femoral morphology and fracture risk in feline THR.

Mechanical behaviour of SiC reinforced aluminium thin walled tube under combined axial and torsional loading

Behavior of long circular SIFCON columns under eccentric loading