Vertical Static Load Research Articles

Experimental and Numerical Investigations on the Spherical Steel Bearing Capacity of New Anti-Separation Design

To solve the issues of slippage and dislodging caused by insufficient grout compactness in railway bridge spherical steel bearings, a novel kind of anti-separation spherical steel bearing is presented. Firstly, a comparative test model was meticulously designed and constructed for the bearing-stone assembly, encompassing both the traditional spherical steel bearing and the innovative anti-separation spherical steel bearing. Next, mechanical performance testing and finite element simulation analysis were completed. Finally, an empirical equation for the vertical load-strain fitting of the bearing was established. The results demonstrate that, under the maximum vertical static load, the convex spherical crown anti-separation design of the new anti-dislodging bearing is not sensitive to the bearing performance of the bearing-bedding stone combination. All indexes also meet the specifications. Under the action of cyclic load, the error of each parameter between finite element analysis and test results is less than 7%, which shows that the new anti- separation spherical bearing has higher bearing capacity and better fatigue resistance; the fitted value of the established bearing vertical load-strain calculation formula is in agreement with the test value by more than 0.95, which can predict whether the new anti-separation bearing fails.

Finite element analysis of the angle range in trans-inferior alveolar nerve implantation at the mandibular second molar

BackgroundTrans- inferior alveolar nerve (IAN) implantation technique was wildly used while the potential appropriate angle range in which the residual alveolar bone can bear the stress without absorption are currently unclear. This study aimed to evaluate the stress distribution pattern of the interface between bone and implant by finite element analysis (FEA) to determine the appropriate range of the implant tilt angle.MethodsCone beam computed tomography (CBCT) images of 120 patients with missing mandibular second molars and vertical bone height < 9 mm in the edentulous area were selected. The distances from the mandibular nerve canal to the buccal cortex, the lingual cortex and the alveolar ridge crest were measured by using a combination of software. The angular ranges of the buccal-lingual inclination of simulated trans-IAN implants were measured and three-dimensional finite element models were constructed in the mandibular second molar area according to the differences of the inclination angles. A vertical load (200N) was then applied to analyze the biomechanical conditions of the implant-bone interface during median occlusion.ResultsThe distance at the second molar from the nerve canal to the buccal cortex, lingual cortex and alveolar crest were 6.861 ± 1.194 mm, 2.843 ± 0.933 mm and 7.944 ± 0.77 mm. Trans-IAN implantation was feasible in 73.33% of patients. The minimum angle and maximum angles of the buccal-lingual inclination of the simulated implant were 19.135 ± 6.721° and 39.282 ± 6.581°. When a vertical static load of 200N was applied, the tensile stress in cortical bone gradually increased with the increase of the implant tilt angle. When the inclination angle reached 30°, the tensile stress (105.9 MPa) exceeded the yield strength (104 MPa) of cortical bone. Compared with the conventional implants, the stress peak value of the vertical ultra-short implant in cortical bone was greater than the stress peak value of the conventional implants at 10°(79.81 MPa) and 20°(82.83 MPa) and was smaller than the stress of the implant at 30°(105.9 MPa) and 40°(107.8 MPa). Therefore, when the bone mass allows, conventional-length implants should be selected whenever possible, and an operative range of the trans-IAN implantation in the mandibular second molar could be retained with an inclination angle of < 30°.ConclusionsThe mandibular nerve canal at the mandibular second molar was obviously biased to the lingual side, which ensured sufficient bone mass at the buccal side. In most patients with severe mandibular atrophy, it was possible to maintain a safe distance from the nerve canal with conventional-length implants via the trans-IAN implantation technique.

Static analysis of the hysteretic performance of the central columns in subway station enhanced by engineered cementitious composite jacket under high variable axial force

Engineered cementitious composite (ECC), a cement-based composite material known for its high tensile strain and ductility, was utilized to enhance the seismic performance and operational safety of the central columns in vulnerable areas of subway stations. By establishing refined solid finite element models of ECC composite columns and ordinary concrete columns, and conducting dynamic time history analysis on the vertical axial force at the top of the column, a comparative analysis was performed using a static model to determine the difference in hysteretic performance between ECC composite columns and ordinary concrete columns. Furthermore, sensitivity analysis is conducted based on different structural parameters. The results demonstrate that ECC composite columns exhibit significant improvements in bearing capacity, ductility, and energy dissipation, while also reducing stiffness degradation compared to ordinary concrete columns under various vertical variable axial loading conditions. Increasing the diameter of longitudinal reinforcement and reducing the stirrup spacing can effectively enhance the bearing capacity and ductility of columns. Additionally, employing an ECC jacket can effectively improve the shear capacity of the columns. Furthermore, modifying the frequency, amplitude, and phase of the vertical axial force will significantly alter the stress distribution and damage failure of the columns.

Effect of slab dimensions on the maximum stress and ultimate vertical load of a 15-story flat slab building

The research of flat slab structures requires more investigation into the full-scale analysis of steel flat slab structures under vertical loads. The impact of slab dimensions on the maximum stress of slabs and columns, as well as the ultimate vertical load at the linear elastic stage, has been examined using full-scale finite element models. The particular structures selected for the analysis are 15-story steel flat slab structures with various slab dimensions under the static vertical load and standard earth gravity. This research also involves: (1) the verification of stress singularity at the corner of cubic columns in the finite element model; (2) the discussion about the variation of maximum stress of slabs and columns as the floor changes, and the interaction of columns and slabs; (3) the validation of the vulnerability of slab-column connection.

Design and finite element analysis of S355J2 wing holders on tank wagons

Wagon component failures that occur during service life can be reduced by applying appropriate geometric changes and using optimization techniques. Therefore, crucial changes are being studied to improve design and performance in structures such as connecting parts, braking systems, suspension, and transmission systems. The wing holders also have a load-bearing feature in connecting the body to the chassis. The strength of the wagon, component stabilization, and weight reduction are of great importance during transportation. In this study, finite element analysis was carried out for the novel type wing holders of the tank wagon system designed via simpler and stepless with various thicknesses. The von Mises stresses and total deformations, as finite element results, for the thicknesses of 10 mm, 12 mm, and 14 mm occurred due to the standard of EN 12663-2:2010 for both longitudinal and vertical loading conditions were extracted from the software. Finally, according to the design improvements, a new wing holder model was developed, which can contribute to the reduction of production and assembly costs.

УВЕЛИЧЕНИЕ ЭНЕРГОЕМКОСТИ ЗАБИВКИ И СОПРОТИВЛЯЕМОСТИ МОДЕЛИ СВАИ С УШИРЕНИЯМИ ПРИ ПОДСЫПКЕ СЫПУЧИХ МАТЕРИАЛОВ

The results of experimental studies of models of piles with 4 widenings performed under laboratory conditions with the addition of bulk materials are presented. It was revealed that the introduction of bulk materials increases the energy costs of clogging models up to 1.14-1.66 times. At the same time, the type of filling material affects the energy intensity of pile driving. It was also found that the resistance of pile models to static vertical loads increased up to 1.15-1.68 times when introducing bulk materials during clogging. It is shown that the type of filling material influences the resistance of pile models to the action of vertical static load.

УВЕЛИЧЕНИЕ ЭНЕРГОЕМКОСТИ ЗАБИВКИ И СОПРОТИВЛЯЕМОСТИ МОДЕЛИ СВАИ С УШИРЕНИЯМИ ПРИ ПОДСЫПКЕ СЫПУЧИХ МАТЕРИАЛОВ

The results of experimental studies of models of piles with 4 widenings performed under laboratory conditions with the addition of bulk materials are presented. It was revealed that the introduction of bulk materials increases the energy costs of clogging models up to 1.14-1.66 times. At the same time, the type of filling material affects the energy intensity of pile driving. It was also found that the resistance of pile models to static vertical loads increased up to 1.15-1.68 times when introducing bulk materials during clogging. It is shown that the type of filling material influences the resistance of pile models to the action of vertical static load.

Effects of spudcan installation processes on the bearing capacity of foundations under combined loading in soft-over-stiff clay

The bearing capacity of spudcan foundations under vertical, horizontal, and moment loading must be adequately assessed prior to the operation of jack-up platforms. However, studies the effects of combined loading on spudcan foundations in soft-over-stiff clays, considering the effect of installation processes, have been limited. In this study, the two-dimensional remeshing and interpolation with small strain method was used to simulate the large deformations experienced by the soil during the installation of a spudcan, and a three-dimensional model was employed for the small strain analysis regarding the bearing capacity. The undrained shear strength of stiff clay influenced the failure mechanisms of the soil during vertical and moment loading. However, it had minimal impact during horizontal loading. Therefore, in this study, an equation for the bearing capacity factors for vertical and moment loading conditions is proposed. The properties and parameters of the combined bearing capacity failure envelope with respect to different dimensions are analysed and corresponding equations for the failure envelope are proposed, which aid the on-site assessment of jack-up platforms prior to them becoming operational.

Plate Load Tests of Soft Foundations Reinforced by Soilbags with Solid Wastes for Wind Farms.

Soilbags are expandable three-dimensional geosynthetic bags made from high-density polyethylene or polypropylene. This study conducted a series of plate load tests to explore the bearing capacity of soft foundations reinforced by soilbags filled with solid wastes based on an onshore wind farm project in China. The effect of contained material on the bearing capacity of the soilbag-reinforced foundation was investigated during the field tests. The experimental studies indicated that soilbag reinforcement with reused solid wastes could substantially improve the bearing capacity of soft foundations under vertical loading conditions. Solid wastes like excavated soil or brick slag residues were found to be suitable as contained material, and the soilbags with plain soil mixed with brick slag had higher bearing capacity than those with pure plain soil. The earth pressure analysis indicated that stress diffusion occurred through the soilbag layers to reduce the load transferred to the underlying soft soil. The stress diffusion angle of soilbag reinforcement obtained from the tests was approximately 38°. In addition, combining soilbag reinforcement with bottom sludge permeable treatment was an effective foundation reinforcement method, which required fewer soilbag layers due to its relatively high permeability. Furthermore, soilbags are considered sustainable construction materials with advantages such as high construction efficiency, low cost, easy reclamation and environmental friendliness while making full use of local solid wastes.

Biomechanical Comparison between Inverted Triangle and Vertical Configurations of Three Kirschner Wires for Femoral Neck Fracture Fixation in Dogs: A Cadaveric Study.

The purpose of this study was to compare single-cycle axial load and stiffness between inverted triangle and vertical configurations of three Kirschner wires (K-wires) for femoral neck fracture fixation in small dog cadaveric models. In each of the eight cadavers, the basilar femoral neck fracture model was prepared on both sides of the femur. One side of the femur was stabilized with three 1.0 mm K-wires of an inverted triangle configuration (group T), and the other femur was stabilized with a vertical configuration (group V). Postoperatively, the placement of the K-wires was evaluated with radiographic and computed tomography (CT) images, and static vertical compressive loading tests were performed. The mean yield load and the lateral spread were significantly higher in group T compared to group V (p = 0.023 and <0.001). On the cross-section of femoral neck at the level of the fracture line, the surface area between K-wires was significantly larger (p < 0.001) and the mean number of cortical supports was significantly higher in group T (p = 0.007). In this experimental comparison, the inverted triangle configuration of three K-wires was more resistant to failure under axial loading than the vertical configuration for canine femoral neck fracture fixation.

Comparison between all-on-four and all-on-six treatment concepts on stress distribution for full-mouth rehabilitation using three-dimensional finite element analysis: A biomechanical study.

The current study intended to provide a comparison of biomechanical behaviors of two different treatment concepts for full-mouth rehabilitation with dental implants placed according to the "All-on-four" concept and "All-on-six" concept with analysis of the stress patterns of the implant support system using three-dimensional finite element analysis (FEA). The edentulous mandible was treated with two different implant designs. "All-on-Four" implant placement concept was used in Model 1 with two central axial implants and two distally tilted implants at 17° and in Model 2, "All-on-Six" concept was applied with six vertically placed implants. Individual vertical and horizontal load of 100 N and oblique load of 141 N at 45° was applied to all implants. To evaluate and compare the results in terms of maximum principal stress, we used FEA. All-on-six showed smaller maximum principal stress values on the cortical bone and implants. However, maximum principal stress values obtained on trabecular bone was smaller in the All-on-four design for vertical and horizontal loading conditions. The All-on-six approach showed more favorable biomechanical behavior.

Driving Features of Tapered-Prismatic Piles and Their Resistance to Static Loads

The field tests of large-scale models of driven tapered prismatic and prismatic piles for driving static vertical and horizontal loads are presented. Field tests were carried out on sandy loam on piles models (M 1:3) with different lengths and cross-sections of the pyramidal segment. It has been established that the driving of tapered-prismatic piles is accompanied by both large (by 1.10-1.60 times) and lower (by 8.0-37.0%) energy consumption for their driving in comparison with conventional prismatic and pyramidal piles. It was also revealed that under the vertical pressing load, the bearing capacity of the tapered-prismatic piles is 1.09-1.48 times, and under the horizontal static load, it is 1.17-1.80 times higher than the prismatic pile. It has been established that with an increase in the length of the pyramidal part of the experimental piles, there is an increase in their bearing capacity by 1.12-1.34 times. Equations are proposed for determining the bearing capacity of tapered-prismatic piles. The research results serve as the basis for the development of recommendations for the calculation and design of tapered-prismatic piles. The revealed features of the behaviour of tapered-prismatic piles allow to reasonably assign the length and dimensions of the cross-section of their pyramidal segment.

Numerical Assessment of Jackup Spudcan Foundations by varying Angle of Spud in 3d Fem in Geotechnical Engineering

A jack-up structure is a bottom-mounted floating unit having an adjustable hull and movable legs. Particular jack-up structures are more susceptible to hazards under environmental loads during their operation and life cycle in the ocean. Authors attempted here to evaluate vertical load carrying capacity of soil and predicting its behaviour. Simulation of loaddeformation behavior under axial compression has been carried out for advancing research. The entire study has been carried out using three-dimensional finite element-based software Plaxis 3D A.E. 2017. The geometrical variation of substructure spud can have an inverted spud at the centre bottom from 1200 to 1800 studied for knowing behaviour under axial compression, axial tension and lateral forces. The simulated numerical model is used to develop empirical expressions for axial capacities estimation. The numerical analysis results indicate that spud can have an inverted angle of cone 1300 which is most beneficial under the static combined vertical, moment and horizontal loading (3D loading) in marine clay. The axial load carrying capacities in compression, tension and lateral loading follow the same sequence in ascending order from 1800,1750, 1500, 1300 and highest in 1200. Stiffness and undrained shear strength of soft clay contribute more than the diameter of the spud and embedment depth in compression and tension.

Different Surgical Techniques in the All-on-4 Treatment Concept: Evaluation of the Stress Distribution Created in Implant and Peripheral Bone with Finite Element Analysis.

To examine the stresses caused by different All-on-4 surgical techniques-conventional, a combination of monocortical and bicortical, bicortical, and nasal floor elevation-on the implant and the surrounding bone using 3D finite element analysis (FEA). A 3D bone model of the atrophic maxilla was created based on CT imaging of the fully edentulous adult patient. All implants used in the models were 4 mm in diameter, and the length was 13 mm in the anterior and 15 mm in the posterior. Implants were applied to four different atrophic maxillary models with the All-on-4 technique: anterior and posterior monocortical implants in the first model, anterior monocortical and posterior bicortical in the second model, anterior and posterior bicortical in the third model, and anterior and posterior bicortical with nasal floor elevation in the fourth model. Eight linear analyses were performed by applying force from both vertical and 45-degree oblique directions to the four models prepared in our study. When the cortical and cancellous bone around the anterior implants was examined, it was observed that the oblique and vertical loading conditions and the stresses around the implant were similar in all models. When the posterior implants were examined, model 1 (ie, anterior and posterior monocortical implants) showed the greatest oblique compression, vertical compression, and vertical tension forces. According to the Von Mises stress (VMS) analysis results for anterior and posterior implants, higher values were observed in model 1 compared to models 3 and 4 under oblique and vertical forces. It was observed that bicortical placement of the implants reduced the stresses on the bone and implant-abutment system but had no significant effect on the stress on the bar. According to the results of our study, in the All-on-4 technique, bicortical placement of the implants reduced the stresses on the bone and implant when the anatomical limitations allowed. In addition, nasal floor elevation can be applied in the atrophic maxilla in appropriate indications.

国宝法起寺三重塔の最上層の構造特性に関する模型実験

In this study, a static vertical load test was conducted on the uppermost layer of the 1/10 model of the Hokiji three-storied pagoda.

Investigations of piles by bidirectional static loading test in Astana soils

The article presents the results of vertical static load tests of diametral and deep bored piles specially conducted at the construction site of EXPO-2017 in Astana, Kazakhstan. The methodology for determining the bearing capacity of the pile is summarized. Bored piles with a length of 31.5 m and a diameter of 1000 mm were tested. Vertical static load tests were conducted for the following load configurations: Bidirectional Static Loading Test (according to ASTM D8169), Static Compression Loading Test according to ASTM D1143-07 and Static Loading Test according to GOST 5686-12. The method presented in the paper can serve as practical guidelines to assess the capacities of bored piles installed in the field. This geotechnical investigation is important for understanding the soil-structures interaction on difficult soil ground conditions related to the construction sites.

Enhancement of the behaviour of reinforced concrete dapped end beams including single-pocket loaded by a vertical concentrated force

In precast building construction, some beams are designed to support one or several concentrated loads resulting from the reactions of the attached cross beams. Consequently, the pocket beams without or with dapped ends may represent one of the innovative solutions to constitute the joints between the two attached members. In the present research work, the behaviour of dapped end beams that included rectangular opening loaded with in-plane force, have been investigated. Several detailing have been proposed, in addition the vertical stirrups, to improve the strength of the opening region including the use of steel fibre concrete (SFC),Configuration of the inclined crossed bars, jacketing with steel plates and the composite section technique with two arrangements of the reinforcement of the dapped end . Ten specimens have been tested under gradually increased vertical static loading. The tested specimens are categorized into two sets based on the configuration of dapped end reinforcement. Two variable have been considered which are the strengthening configuration of the opening region and the configuration of the dapped end reinforcement. The response has been discussed in terms several indicators including, the cracking and failure loads, maximum deflection, mode of failure, load-deflection curves, crack patterns, crack width, to recognize the optimum strengthening proposal of the opening. Results revealed that using the inclined steel bars (modified arrangement) yield better response than the conventional (standard) reinforcement (vertical stirrups) within the dapped end. For beams with pockets strengthened with crossed inclined bars, failure load enhanced in range of (8.5-11%) whereas the enhancement was in ranged in (8-10%) for the steel SFC method. Moreover, an improvement by about (11-13%) in load capacity increased when the jacketing with steel plates was applied. The maximum improvement was obtained when using the embedded rolled section within the opening with values of (21-23%).

Testing pile foundations at the ETH Zurich drum centrifuge: recent developments

Motivated by the need to develop rational design methods for the retrofit of existing bridges on pile groups, this paper introduces recent experimental developments at the ETH Zurich drum centrifuge in Switzerland. Four set-ups are developed for vertical, pushover, combined and vibration testing. Their capabilities and limitations are demonstrated using as an example a 2 × 1 pile group on dense saturated sand. Single piles are subjected to vertical loading, exploring the role of installation effects and interface roughness. Pushover loading is employed to measure the moment capacity [Formula: see text] of a lightly and a heavily loaded group. In contrast to intuitive expectations, the heavily loaded system mobilises larger [Formula: see text]. The developed combined loading apparatus is proof-tested for a shallow foundation. Combined loading under constant vertical load is conducted to derive failure envelopes, revealing significant coupling between lateral and moment loading, and confirming the expansion of the failure envelope with increasing static vertical load. The vibration testing set-up is proof-tested, confirming the possibility of identifying the natural frequency of the system and the small-strain stiffness of the foundation through non-destructive testing. Although the study is fuelled by the ongoing work on pile groups, the developed experimental set-ups are of general applicability for the study of deep and shallow foundation systems.

BEARING CAPACITY AND SLIDING RESISTANCE OF SPREAD FOUNDATION UNDER VERTICAL AND LATERAL COMBINED LOAD

To clarify behavior and sliding resistance of a spread foundation under combined load, static vertical loading test, and static vertical and lateral combined loading tests were conducted on a spread foundation on sand. The sliding resistance under the combined load was caused by the soil failure beneath the foundation. After the peak of the lateral resistance, settlement and horizontal displacement increased although vertical and lateral load did not increase. When the vertical load is less than about 1/2 of the ultimate bearing capacity, the vertical load could be retained and the horizontal displacement was greater than the settlement.

Enhancing the Life Cycle of the Jack up Structure by Applying Alternative Foundation Methodologies in Geotechnical Engineering

A jack-up structure is a bottom-mounted floating unit having an adjustable hull and movable legs. Particular jack-up structures are more susceptible to hazards under environmental loads during their operation and life cycle in the ocean. Authors' attempts here to enhance its life cycle and sustainability in shallow to deep waters by correctly accessing soil behaviour and predicting its load carrying capacity. Here the numerical analysis of the substructure has been attempted. Simulation of load-deformation behavior under axial compression has been carried out for advancing research. The entire study has been carried out using three-dimensional finite element-based software Plaxis 3D A.E. 2017. The geometrical variation of substructure spud can have an inverted spud at the centre bottom from 120 0 to 180 0 has been studied for knowing behaviour under axial compression, axial tension, and lateral forces. The simulated numerical model is used to develop empirical expressions for axial capacities estimation. The numerical analysis results indicate that spud can have an inverted angle of cone 130 0 is most beneficial under the static combined vertical, moment, and horizontal loading (3D loading) in marine clay. The axial load carrying capacities in compression, tension, and lateral loading follow the same sequence in ascending order from 180 0 ,175 0 , 150 0 , 130 0 and highest in 120 0 . Stiffness and undrained shear strength of soft clay contribute more than the diameter of the spud and embedment depth in compression and tension.