Fracture and stability analysis of knee-braced column footings under eccentric loading using finite element modelling

To obtain the pressure distribution model on the sole plate of semi-rigid light steel column footing, the deflection formulas of beams with free ends on elastic foundation subjected to arbitrarily concentrated load and arbitrarily trapezoidal load were developed by applying the Winkler model of elastic foundation beam and initiate-parameter expressions of deformation and internal force by presetting boundary condition and calculating with Maple software. The sole plate of semi-rigid square steel tube column footing was converted into elastic foundation beam which is supported by concrete foundation, the mechanical model of the sole plate subjected to eccentric load was obtained, and the theoretical solution of pressure distribution on the sole plate was presented. Then the theoretical solution was compared with the numerical solution via an example. The results show that the two solutions meet well with each other, and there is much great difference between the pressure distribution on sole plate of semi-rigid light steel column footing and the linear pressure distribution model in common use. As a result, the semi-rigid column footing stiffness would be overestimated by using linear pressure distribution model. The fruits presented in this paper are useful and convenient to the design of semi-rigid light steel column footing.

The effect of biaxial compressive loading on hollow steel box column (HSBC) and concrete-filled steel box column (CFSBC) sections wrapped with low-modulus carbon-fibre-reinforced polymer (CFRP) was studied. The CFSBC and HSBC sections were simulated using Abaqus finite-element software and validated using available experimental data. Biaxial compressive loading was considered for different eccentricities (i.e. eccentricity to depth ratio (e/D) ratio of zero to 0.32). The results indicated that, for CFRP-wrapped HSBCs at low eccentricity (e/D = 0.08), compact and non-compact sections were effective at carrying higher load, while a slender section was effective for concentric loads. For the CFRP-wrapped CFSBCs, compact and non-compact sections were effective for all the eccentric loads (e/D = 0–0.32). It was also found that the low-modulus CFRP layer wrapping the CFSBC sections had no significant effect on strength. An empirical relationship was developed based on trend analysis, which gives the load-carrying capacity of any section. For the CFSBC sections, axial compression–uniaxial moment (P–M) interaction curves are presented to validate the simulation results under biaxial loading.

Background: The success of combined prosthodontics and implant treatments is influenced by various biomechanical factors, including load distribution, stress distribution, and material selection. These factors play a critical role in determining the longevity and functionality of implant-supported prosthetic restorations. Aim: This study aimed to explore the biomechanical factors influencing the success of combined prosthodontics and implant treatments, focusing on load distribution, stress distribution, and material selection. Materials and Methods: A prospective observational study was conducted with a sample size of 30 patients requiring implant-supported prosthetic restorations. Standard titanium implants were placed, followed by the application of prosthetic components fabricated from materials such as zirconia, porcelain-fused-to-metal, monolithic zirconia, and composite resin. Cone-beam computed tomography and finite element analysis were used to assess the load and stress distribution. Intraoral sensors measured occlusal load, and data were collected at 3, 6, and 12 months post-prosthesis placement. Results: Posterior mandibular implants exhibited the highest mean occlusal load (220 N), with a significant variability among patients. Zirconia and monolithic zirconia prosthetics demonstrated the lowest mean stress (750 and 700 MPa, respectively) and no fracture incidents, whereas composite resin showed the highest mean stress (900 MPa) and the most fractures. These findings highlight the importance of appropriate material selection and biomechanical planning to prevent implant overload and prosthetic failure. Conclusion: Biomechanical factors, including load and stress distribution, along with careful material selection, are crucial for the success of implant-supported prosthetic restorations. Posterior regions, especially the mandible, require meticulous planning to distribute the occlusal forces evenly. Zirconia and monolithic zirconia materials are recommended for high-load areas due to their superior mechanical properties and fracture resistance.

Fatigue life analysis is often overlooked in ship development, leading to an uncertain understanding of a ship’s construction lifespan. This study focuses on the fatigue life of the car deck, which is affected by deformation on a ro-ro ferry. The research aims to determine the maximum stress, location, the cause of deformation, and the fatigue life of the car deck on a ro-ro passenger ship. The calculations assess the car deck’s lifespan and provide a reference for future design considerations. Finite element analysis (FEA) is used, with fatigue life calculated using the Sonderberg method. The research begins with calculating the ship’s weight and buoyancy distribution, then determining the ship’s longitudinal strength from the load distribution. The analysis reveals that the highest stress occurs under hogging wave conditions, exceeding the yield strength of 321 MPa. Specifically, at overload and hogging wave conditions, the highest stress of 486.1 MPa is found on the starboard side between longitudinal stiffeners 1 and 2 (900 mm from the centerline), between frames 56 and 57, with a fatigue life of 4.3 years.

Experimental and numerical study of resistance of multi-cell L-shaped concrete-filled steel tubular stub columns under biaxial eccentric compressive loading

Multi-body contact in non-linear dynamics of real mechanical systems

The Sagamore Parkway Bridge consists of twin parallel bridges over the Wabash River in Lafayette, IN. The old steel-truss eastbound bridge was demolished in November 2016 and replaced by a new seven-span concrete bridge. The new bridge consists of two end-bents (bent 1 and bent 8) and six interior piers (pier 2 to pier 7) that are founded on closed-ended and open-ended driven pipe piles, respectively. During bridge construction, one of the bridge piers (pier 7) and its foundation elements were selected for instrumentation for monitoring the long-term response of the bridge to dead and live loads. The main goals of the project were (1) to compare the design bridge loads (dead and live loads) with the actual measured loads and (2) to study the transfer of the superstructure loads to the foundation and the load distribution among the piles in the group. This report presents in detail the site investigation data, the instrumentation schemes used for load and settlement measurements, and the response of the bridge pier and its foundation to dead and live loads at different stages during and after bridge construction. The measurement results include the load-settlement curves of the bridge pier and the piles supporting it, the load transferred from the bridge pier to its foundation, the bearing capacity of the pile cap, the load eccentricity, and the distribution of loads within the pier’s cross section and among the individual piles in the group. The measured dead and live loads are compared with those estimated in bridge design.

Evaluation of Load Distributions in Pushover Analysis Nonlinear pushover and time history analyses are common used methods to determine the nonlinear behavior of structures under earthquake loading. The aim of the present study is to evaluate the push over analysis, which is commonly used to determine the performance of R/C structures, comparing with time history analysis. For this purpose, 3, 5, 8 and 15-story R/C frame structures with various natural periods are analyzed by performing nonlinear pushover and dynamic time history analyses. The load distributions for pushover analyses are chosen as rectangular, triangular (IBC, k=1) and parabolic (IBC, k=2). To evaluate the results from the pushover analysis, nonlinear dynamic time history analysis is performed for 50 different stations’ data during various earthquakes. Finally, the best load distribution is determined for pushover analysis and the results are evaluated regarding with story height of the selected structures.

Stability and anchorage considerations for cementless tibial components

Efficacy of roof-to-beam mechanical connections on the diaphragm behaviour of precast decks with spaced roof elements

Behavior of concrete-filled T-shaped steel tubular beam-columns under biaxial compressive loads

To enhance the structural performance of concrete-filled steel tube (CFST) columns, various strengthening techniques have been proposed, including the use of internal steel stiffeners, external wrapping with carbon fiber-reinforced polymer (CFRP) sheets, and embedded steel elements. However, the behavior of concrete-filled stainless-steel tube (CFSST) columns remains insufficiently explored. This study numerically investigates the axial performance of square CFSST columns internally strengthened with embedded I-section steel profiles under biaxial eccentric loading. Finite element (FE) simulations were conducted using ABAQUS v. 6.2, and the developed models were validated against experimental results from the literature. A comprehensive parametric study was performed to evaluate the effects of several variables, including concrete compressive strength (fcu), stainless-steel yield strength (fy), the depth ratio between the stainless-steel tube and the internal I-section (Dst/Dsi), biaxial eccentricities (ex and ey), and tube thickness (t). The results demonstrated that the axial performance of CFSST columns was most significantly influenced by increasing the Dst/Dsi ratio and load eccentricities. In contrast, increasing the concrete strength and steel yield strength had relatively modest effects. Specifically, the ultimate axial capacity increased by 9.97% when the steel yield strength rose from 550 MPa to 650 MPa and by 33.72% when the tube thickness increased from 3.0 mm to 5.0 mm. A strength gain of only 10.23% was observed when the concrete strength increased from 30 MPa to 60 MPa. Moreover, the energy absorption index of the strengthened columns improved in correlation with the enhanced axial capacities.

Performance analysis of functionally graded multifunctional piezoelectric energy harvesting microgyroscopes

Loading and contact stress distribution on the thread teeth in tubing and casing premium threaded connections are of great importance for design optimization, pretightening force control, and thread failure prevention. This paper proposes an analytical method based on the elastic mechanics. This is quite different from other papers, which mainly rely on finite element analysis. The differential equation of load distribution on the thread teeth was established according to equal pitch of the engaged thread after deformation and solved by finite difference method. Furthermore, the relation between load acting on each engaged thread and mean contact stress on its load flank is set up based on the geometric description of thread surface. By comparison, this new analytical method with the finite element analysis for a modified API 177.8 mm premium threaded connection is approved. Comparison of the contact stress on the last engaged thread between analytical model and FEM shows that the accuracy of analytical model will decline with the increase of pretightening force after the material enters into plastic deformation. However, the analytical method can meet the needs of engineering to some extent because its relative error is about 6.2%~18.1% for the in‐service level of pretightening force.

Shape Memory Alloys (SMAs) are unique materials capable of recovering predefined shapes through reversible phase transformations between austenite and martensite phases. This behavior enables SMAs to exhibit the shape memory effect and pseudoelasticity, allowing for the recovery of large strains and the generation of significant forces. These properties make SMAs highly desirable for applications in actuation, sensing, and other engineering domains. Conventional SMA actuator designs, while effective, often face limitations such as slow response times, non-uniform stress distribution, and reduced fatigue life under cyclic loading.
Integrating Kirigami-inspired techniques into SMA actuator design addresses these challenges by introducing precise cut patterns that transform 2D SMA materials into complex 3D structures. Kirigami-based SMA structures offer enhanced stroke lengths, improved heat dissipation, and uniform load distribution, reducing stress concentrations and extending actuator lifespan. This approach enables the creation of versatile and efficient actuators with tailored mechanical properties, overcoming traditional design constraints.
This paper presents a constitutive model for Kirigami-based SMA structures, coupling mechanical deformation and thermal response modeling to capture in-plane and out-of-plane deformations. The proposed framework provides a detailed understanding of the unique thermomechanical behavior of Kirigami-inspired SMA actuators, offering insights into their performance under varying operational conditions. The findings highlight the potential of Kirigami-based SMA structures for advancing actuator technologies across a range of applications.