Friction Capacity Research Articles

Development of linear bearing equipment for modal testing of low-frequency weakly damped spacecraft structures

This article presents the results of a study of the bearing capacity and dissipative properties of an aerostatic linear bearing developed at JSC RESHETNEV for modal testing of complex structures. When selecting equipment for modal testing, the main condition is the requirement to minimize the distortions introduced into the determined dynamic characteristics: frequencies of natural vibration modes, the vibration modes themselves, as well as modal masses and damping coefficients. In other words, all equipment used for ground-based modal testing should ideally have zero added mass, stiffness and friction. The main systems containing elements that create dissipative forces that affect the determination of damping coefficients are systems for weight compensation and vibration excitation on natural modes. The weight compensation system usually contains either elastic elements or a system of guides with rolling or sliding bearings. If the former bring additional rigidity and mass to the test object, the latter bring mass and friction (dry or viscous), which increases the error in determining the dynamic characteristics. The excitation of vibrations on natural modes, in most cases, is carried out by electrodynamic vibrators consisting of a magnetization coil (or permanent magnet) and a movable coil moving in a magnetic gap. The movable coil is oriented in the magnetic gap using a special system containing either elastic elements or a linear guide bearing. Vibrators with elastic coil suspension elements cannot be used for modal tests of extended structures with low rigidity. The problem of creating an ideal bearing to replace classic linear (sliding or roller) ones arose during preparation for modal tests of the wing of a solar battery of a spacecraft (SC). Aerostatic bearings (supports) have virtually zero friction and sufficient load-bearing capacity, in which compressed air acts as a lubricant, eliminating physical contacts of the interacting surfaces. To confirm the possibility of using aerostatic bearings in equipment for conducting modal tests of extended structures with low frequencies of natural oscillations, comparative tests of a roller and aerostatic bearing were carried out. During the tests, optimal air flow parameters (nozzle diameter, operating pressure and gap) were selected, which ensure the required load-bearing capacity for radial forces and torques (bending and torsion). A comparative assessment of dissipative properties was carried out when measuring the attenuation parameters of single-mass harmonic oscillators, which include aerostatic and roller linear bearings. With a nozzle diameter of 0.6 mm, a working gap of 40 μm and a bearing input pressure of 1.0 bar, the logarithmic decrement of oscillations of the harmonic oscillator with an aerostatic bearing was 0.084, which is more than 28 times lower than the logarithmic decrement of oscillations of an oscillator with a roller bearing. The conducted studies confirmed the possibility of using the developed aerostatic bearing in test systems used in modal tests of large-sized transformable spacecraft structures.

Frictional pull-out work capacity of macro-SSF in concrete composites and evaluation of matrix deterioration due to kinematic fiber-end-slip after full-debonding point

ABSTRACT This paper presents a parametric study on the effect of frictional pull-out work capacity on the performance of fiber/matrix regime during the kinematic pull-out process. This study involves an experimental program of pull-out test of straight steel fiber embedded in concrete composites, numerical study based on finite element modeling, and theoretical approaches based on mathematical model. Various parameters were considered such as fiber geometry, Poisson’s ratio, elasticity modulus, and aspect ratio. The experimental results were calibrated with the results of numerical study, and the theoretical approaches were controlled using deterioration coefficient based on a given curve of uniaxial stress–displacement relationship plotted experimentally. The results showed that the capacity of pull-out work decreases 62.6% when the fiber diameter decreases 6 times. Decreasing the fiber diameter also improves the resistance of the matrix against deterioration. While decreasing the fiber embedded length by 1.8 times, the frictional pull-out work decreases by 56.3% and boosts relatively the resistance of matrix against crumbling, where the frictional shear bond strength improved by 91%. Likewise, decreasing the fiber aspect ratio by 1.8 times decreases the done frictional pull-out work by 56.3% and boosts the fiber duct resistance against damage by improving the frictional shear bond strength.

Experimental investigation of traditional Kath-Kuni wall system and traditional joints

In the Indian Himalayan region, the traditional vernacular construction system is a centuries-old system that is considered a seismic-resistant construction system. This practice is developed in the area over a period of time by the local communities and is never conventionally engineered. Hence, it is important to know about the behaviour of traditional construction systems and key features associated, under gravitational and lateral loading conditions. In the present research, experimental studies have been done on the full scale as well as scaled-down kath-kuni wall specimens, under push-over loading conditions, to characterize its overall behaviour, deformation and earthquake-resisting features. The failure of the kath-kuni wall was governed by friction capacity reduction followed by internal rotation in wooden layers. The kath-kuni system showed high ductile behaviour and the behaviour factor R was calculated as more than 5.4, and was compared with conventional brick masonry. The joints in the kath-kuni wall system have been identified and separate experimental studies, with varying member sizes, have been conducted to find out behaviour and capacity of these traditional joints upon loading. Analytical equations, to calculate capacity, have been proposed and compared with experimental results. The coefficient of friction was found to be varying in between 0.42–0.8 for different surfaces under constant overburden.

STUDI KOMPARASI KAPASITAS DUKUNG RENCANA DAN KAPASITAS DUKUNG AKTUAL FONDASI TIANG PANCANG PADA KONSTRUKSI SLAB ON PILE JALAN TOL SEMARANG – DEMAK SEKSI 2

Semarang - Demak Toll Road Section 2 with a length of 16.31 km crosses the North Coast of Java. The regional geological map shows that the North Coast of Java has alluvial soil layers with clay and silt characteristics. The results of soil investigations show that the depth of the soft layer reaches more than 60 m. This condition triggers construction engineering to support the Highway above it. One of the efforts to fulfill the elevation plan (finish grade) is the flyover concept with slab on pile construction. The planned traffic lane is laid on a concrete slab which is supported by piles with a diameter of 600 mm. With sufficiently deep soft soil layers, the bearing capacity of the foundation piles is borne by the frictional resistance provided by the soil along the piles. This comparative study compares the planned carrying capacity calculated by the empirical formula with the actual carrying capacity of the field as a result of the PDA Test. Calculations were made on 5 test poles for later comparisons were made with the PDA test record data. For the case of 14 days driving at the research location, the pile bearing capacity from the PDA test results is still below the design bearing capacity. The average actual carrying capacity obtained from the 5 test piles is 278 tons. This value is below the planned carrying capacity of the Shio & Fukui method of 381 tons, Meyerhoff's 355 tons, Biaud et al's 777 tons, and Luciano Decourt's 605 tons. At the age of the pile 14 days after the erection was completed, the results of the calculation of the bearing capacity of the Meyerhoff method are closest to the actual bearing capacity of the PDA test results with a ratio of 1.26. The next method is Shio & Fukui with a ratio of 1.36, Luciano Decourt (2.16), and Biaud et al (2.81). Some of the results of previous studies showed a positive correlation between the age after completion of the pile and the frictional carrying capacity. For this type of friction pile, this is of course very influential, so that it is possible that when it is realized that it is carried out with a longer service life, the actual bearing capacity obtained will increase. This requires further research to obtain a time relationship with an increase in pile bearing capacity, especially for locations that have deep soft soil layers such as in this study location.

Evaluation of Design Parameters (α and β) for Analysis and Design of Piles on Soft Clays

This paper presents the analyses of 12 prestressed concrete instrumented test piles (TPs) that were driven in different bridge construction projects of Louisiana as part of a load testing program. The 12 TPs were driven mainly in cohesive soils. Detailed soil characterizations including both laboratory and in situ tests were conducted to determine the different soil properties. The TPs were instrumented with vibrating wire strain gauges to be able to calculate the distribution of skin friction and end-bearing capacities separately. Static load tests and dynamic load tests were conducted on each TP after end of driving to calculate the ultimate load capacity. Fifty six soil layers exhibiting clayey soil behavior and sandy soil behavior dominated the remaining 15 soil layers. The total stress parameter (α) and the effective stress parameter (β) were back-calculated for each soil layer. The α values ranged from 0.22 to 1.80, and the β values ranged from 0.11 to 0.83. Regression analyses were performed on 42 soil layers (75% data) to develop an empirical model to predict α as a function of undrained shear strength. The remaining 25% of the data were used to verify the developed model, and good agreement was observed between the measured and predicted values.

Experimental investigation and analytical model of traditional Kath-Kuni Wooden joints

ABSTRACT The traditional Kath-Kuni construction system is considered an earthquake-resistant construction system. Its major earthquake-resistant features are its wooden connections, such as Maanwi (dovetail), Kadil (dowel), and friction capacity between layers. Hence, in the present research, experiments have been done to understand the behaviour and failure mechanism of these wooden joints, and their moment-carrying capacities have been calculated. In experimental studies, varying sizes of members and connection keys for Maanwi, Kadil, and different materials for friction coefficient have been considered. Analytical equations for various failure mechanisms have been proposed to understand the behaviour, failure mechanism and capacities, analytically, and the results are compared with the experimental data. Brittle failure was observed for both the Maanwi and Kadil connections. The capacity of the Maanwi connection was governed by the area available to resist the rotation and wood tensile capacity in the perpendicular grain direction. The Kadil connection capacity depends upon the Kadil key's size and the wood's capacity in tension and torsion-induced shear in the perpendicular grain direction. The friction coefficient was found to vary from 0.45 to 0.80 between different surfaces under constant overburden.

Shear friction capacity of monolithic construction joints reinforced with self-prestressing reinforcing steel bars

The shear friction capacity (SFC) of a monolithic concrete interface reinforced with newly developed self-prestressing reinforcing steel bars (SPRBs) was examined. A total of 12 SPRB-reinforced push-off specimens with different concrete compressive strengths (f′c) were prepared and different compressive stresses (σx) were applied to the monolithic concrete interface. To compare the SFCs of monolithic concrete interfaces reinforced with conventional reinforcing bars, four companion specimens were prepared. The test results showed that the shear cracking and SFCs were high for specimens with high f′c and σx values, with highest values for specimens with f′c = 40 MPa and σx = 0.5fy (fy is the yield strength of the reinforcing steel bar). The test results confirmed that, at a similar reinforcement index ((ρvffy + σx)/f′c) (ρvf is the transverse reinforcement ratio), σx > 0.35fy is required for the SPRBs to achieve a SFC (λn) comparable to that of specimens reinforced with conventional reinforcing bars. Code prediction models were found to underestimate the SFC significantly. In addition, the difference between the experimental and predicted values increased with an increase in (ρvffy + σx)/f′c. However, Mattock's model produced good estimates of the measured SFCs of all the specimens tested in this study, irrespective of the values of ρvffy and σx. The mean and standard deviation of the measured-to-predicted SFC ratio were 1.07 and 0.13, respectively.

Experimental study on the frictional capacity of square pile–cemented soil interface with different surface roughness

Experimental study on the frictional capacity of square pile–cemented soil interface with different surface roughness

The study on modulation mechanism for anti-corrosion and low-friction of R0-MoS2 by Ti-/Pb-doped model

Based on the first principles, the mechanism of the corrosion and friction failure of 2S-MoS2 (MoS2 stands for R0-MoS2 structure), of the anti-corrosion and friction modulation of Ti-/Pb-doped MoS2 are revealed in the atmosphere environment. For 2S-MoS2, O-doped and H2O-adsorbed 2S-MoS2 interface are formed with interlayer electron reconfiguration, which form the local MoO3 particles and increases their sliding barrier. Although the anti-corrosion role can be shown by trapping interlayer O2/H2O in 2Ti(23)-MoS2 +O2/H2O or by forming a clean Pb-doped interlayer in 2Pb(14)-MoS2 +O2/H2O, the tribological modulation effect occurs only 2Pb(14)-MoS2 +O2/H2O. Compared with 2S-MoS2 +O2/H2O, the tribological performance of 2Pb(14)-MoS2 +O2/H2O is improved by 31.4%/35.2%. These are attributed to 2Pb(14)-MoS2 +O2/H2O with O-passivated structure (S-O/O-S)/H2O-intercalated structure (S/H2O/S) that presents lower shear strength. However, 2Ti(23)-MoS2 +O2/H2O with the cross-linked structure (Ti-O-O-Ti/Ti-OH-Ti) shows higher shear strength. In addition, the ultra-low friction (improved by 26.3%/32.8%, compared with 2S-MoS2 in vacuum) and load-carrying capacity of 2Pb(14)-MoS2 +O2/H2O are also presented and 2Pb(14)-MoS2 +H2O is more excellent (improved by 8.8%, compared with 2Pb(14)-MoS2 +O2). In summary, the tribological modulation of Ti/Pb-doped MoS2 in the atmosphere environment is relative to the structure of their anti-corrosion interface.

Effect of Pile Thread Spacing on the Friction Resistance of Minipile

This study aims to determine the most effective type of pile foundation between threaded sleeve piles with a 10 cm spacing and threaded pile piles with a 20 cm spacing, focusing on their frictional bearing capacity. Test specimens were prepared using reinforced concrete with a compressive strength of K-350 kg/cm2, reinforced with 4D10 mm longitudinal bars and Ø8-150 mm stirrups. Measurements of pile settlements were taken over several days to assess their behavior under load. Results indicated that piles with a 10 cm thread spacing exhibited a settlement of 3.7 mm on the first day, while those with a 20 cm spacing settled by 4.2 mm, with a percentage difference of 29.6%. The study concludes that rougher surfaces (tighter threads) yield greater frictional forces, thereby enhancing pile bearing capacity. Additionally, settlements tended to stabilize over time, with piles at 20 cm spacing experiencing a quicker cessation of settlement compared to those at 10 cm spacing. This research provides valuable insights for foundation engineering, material technology, and concrete construction practices. It also offers practical implications for the pile manufacturing industry.

Competition-Induced Macroscopic Superlubricity of Ionic Liquid Analogues by Hydroxyl Ligands Revealed by in Situ Raman.

High load-bearing capacity is one of the crucial indicators for liquid superlubricants to move toward practicality. However, some of the current emerging systems not only have low contact pressures but also are highly susceptible to further degradation due to water adsorption and even superlubricity failure. Herein, a novel choline chloride-based ionic liquid analogues (ILAs) of a superlubricant with triethanolamine (TEOA) as the H-bond donor is reported for the first time; it obtains an ultralow coefficient of friction (0.005) and high load-bearing capacity (360 MPa, more than 2 times that of similar systems) due to adsorption of a small amount of water (<5 wt %) from the air. In situ Raman combined with 1H NMR and FTIR techniques reveals that adsorbed water competes with the hydroxyl group of TEOA for coordination with Cl-, leading to the conversion of some strong H-bonds to weak H-bonds in ILAs; the localized strong H-bonds and weak H-bonds endow the ILAs with high load-bearing capacity and the formation of ultralow shear-resistance sliding interfaces, respectively, under the shear motion. This study proposes a strategy to modulate the interactions between liquid species using adsorbed water from air as a competing ligand, which provides new insights into the design of ILA-based macroscopic liquid superlubricants with a high load-bearing capacity.

Static Load Testing of Instrumented Screw Piles in Soft Soil Deposits

With the rapid development across major cities, low-capacity screw piles are adopted by builders as a viable economical option in managing risk involving settlement in soft soil deposits. Although the required installation torque and the capacity of a screw pile can be correlated to the soil shearing resistance at the interface of its shaft and helical plates, the correlated ultimate capacity of the pile is specific only to undrained conditions. Therefore, if the water table fluctuates within the embedment length of the pile, the correlated ultimate strength is not valid. This poses a serious design concern in over-consolidated fills. Therefore, due to the uncertainty associated with the compressive capacity of installed screw piles in soft saturated deposits, it is advantageous to perform a static load test to verify the serviceability and ultimate loads. In this study, four static load tests were carried out on screw piles at four different construction sites in the city of Melbourne, to study the load transfer mechanism at various levels of axial loading and subsequent unloading/reloading stages. In one of the sites, the screw pile was equipped with miniature transducers to monitor the generated total stress and pore-water pressure during the installation and post-installation. The results of this study indicated that a static load test can accurately estimate the real bearing capacity of a screw pile which differs significantly from the design geotechnical strength calculated using theoretical equations. It was concluded that in the absence of a pile load test, it is rational to adopt a geotechnical reduction factor of 0.4 and neglect the skin friction capacity of the screw pile to provide a safe foundation design.

Evaluating Differences in Foundation Depth Planning and Implementation for Building Structure Safety

Kediri has been named the Most Sustainable City. To support this, Kadiri University also contributed by building lecture buildings. In its implementation, there is a difference in the depth of the foundation from the initial plan. This causes the need for evaluation to ensure the safety of the building structure. This research aims to identify (Cone Penetration Test) CPT distances, depth differences, negative skin friction, settlement, and empirical bearing capacity calculations on the safety of building structures on sandy soil. The direct observation method was used to obtain data. The analysis includes a comparison of depth, negative skin friction values, settlement, and bearing capacity. The research results show that the average CPT distance is 18.22 m, which can result in inaccurate CPT data because differences in soil structure can occur. A depth difference of 22% from the plan can be considered safe for the structure. This is validated by a field settlement of 2 mm lower than the maximum settlement limit and a Negative skin friction value of 0, indicating no additional settlement. These parameters indicate that the structure is safe. The modified Meyerhoff and Trofimankove methods are suitable for planning foundations with sandy soil because they can meet the load received. This research can add empirical evidence in evaluating structural safety for different depths of foundation planning and implementation in sandy soil-based projects, as well as reducing the potential risk of structural failure in the long term.

Enhancing the bearing capacity of friction anchor bolts through cementitious concrete injection for reinforced support in underground mine

Friction anchor bolts are commonly used for providing support in underground structures by relying on frictional forces between the bolt and the surrounding rock. This study proposes a method to enhance the efficiency of these bolts by injecting a cement-based mixture comprising cement, sand, and additives. The injection of this mixture into the bolt results in internal expansion, which reinforces the friction and bearing capacity of the bolt. The increased volume exerts a radial force, leading to improved adherence, load transfer, and void filling. Pullout tests were conducted on various rock masses to evaluate the performance of the anchor bolts. The results demonstrate increased pullout resistance with higher rock mass quality and longer cemented bolts. Additionally, the use of a silicate-based additive accelerated the curing time of the cement, enhancing the strength of the bolts. The study also highlights the significant influence of groundwater on the bearing capacity of the bolts. These findings indicate the effectiveness of cemented concrete injection in strengthening friction anchor bolts and their anchorage in underground structures.

Geotechnical investigation and stabilization of soils through limestone powder at Abbottabad, Khyber-Pakhtunkhwa, Pakistan: a cost effective and sustainable approach

This study was designed to determine the geotechnical parameters and stability of soils in the Abbottabad region of Khyber-Pakhtunkhwa, Pakistan. The seven major sites with high population density were selected, covering the entire city, which includes Kalapul, Mandian, Jhangi, Nawanshehr, Cantonment, Abbottabad Courts and Jinnahabad. A total of thirty-two (32) boreholes were drilled to a depth of 5 m for standard penetration assessment and thirty two (32) field densification tests were performed at the designated sites. The standard penetration tests were carried out at every meter depth of the bore hole for recording penetration resistance, bearing potential and sample collection. Laboratory tests consisting of Grain-size analysis, Atterberg limits, California Bearing Ratio (CBR), Unconfined Compressive Strength (UCS), Direct Shear Box, and Proctor Compaction were conducted according to the ASTM standards on the accrued samples. The values of the performed tests were utilized for soils characterization and inspecting the Liquidity Index, Consistency Index, and Foundation evaluation for quite a number of footings. The results showed that most of the soils of the area belong to the Clay category (CL and A6 class) with excessive values of Plasticity Index (16.9%–18.6%), Liquidity Index (−47.33% to −23.07%) and Lower CBR (3%–6%), Angle of Internal Friction (15°–20°), UCS (79 kPa–121 kPa), Dry Density (15.13 kN/m3–17.66 kN/m3), Consistency Index (123.07%–147.33%) and Bearing Capacities, except the parts of Kalapul area, which belonged to the GP (poorly graded gravels) category with significant geotechnical properties. Based on the obtained results, we found that the land in the vicinity needs significant improvement before construction. For this purpose, various concentrations of limestone (12.5% and 25%), which is heavily mined in the area, were used as an additive. The results showed that the addition of limestone powder produced a significant improvement in all investigated properties and made the soft soil suitable for construction, in addition to any extended stabilization measures. The main reason for this improvement is the presence of more dense and lower water-absorbing minerals in the limestone than in the ground, or mineralization reactions between them.

Predicting friction capacity of driven piles using new combinations of neural networks and metaheuristic optimization algorithms

Friction capacity is a principal characteristic in designing driven piles. Considering the complexities in analyzing the behavior of piles, many studies have recommended the use of machine learning for this purpose. However, the used methodologies need to be updated and improved with respect to recent computational advances such as the development of optimization algorithms. In this work, three metaheuristic algorithms, namely equilibrium optimizer (EO), biogeography-based optimization (BBO), and salp swarm algorithm (SSA) are deployed to optimize an artificial neural network (ANN) for predicting pile friction capacity based on pile geometry, effective stress, and shear strength. The findings indicate the suitability of the proposed algorithms. More specifically, in the training phase, the ANN supervised by SSA yielded the most accurate results, whereas in the testing phase, the BBO-ANN outperformed the two other models. The calculated mean absolute error, Pearson correlation coefficient, and root mean square error for the models are as follows: 6.0740, 0.9385, and 7.0678 for the EO-ANN, 6.1450, 0.9440, and 6.7343 for the BBO-ANN, and 5.9684, 0.9395, and 7.1322 for the SSA-ANN. It is shown that both SSA-ANN and BBO-ANN can serve as efficient tools for the reliable design of driven piles, providing efficient computational intelligence alternatives to traditional design methods.

An Experimental Study on Estimation of the Lateral Earth Pressure Coefficient (K) from Shaft Friction Resistance of Model Piles under Axial Load

Estimating a pile shaft’s frictional capacity is challenging and has been a controversial subject among researchers. In this study, the shaft friction resistance of non-displacement (pre-installed) model piles under axial load was investigated. Four different model piles were used, including steel, timber, and two composite piles (FRP and PVC filled with concrete). The angle of interface friction (δ) between test sand, and pile materials was determined using an interface shear test (IST) at four relative densities. Axial pile load experiments were implemented in a soil tank and piles were embedded into loose to very dense sand. Model pile load tests were performed in such a way that there was no end (point) bearing capacity (only friction was generated), and lateral friction resistance between the pile material and the soil along the pile shaft formed the complete bearing capacity of the model pile. According to experimental results, it was observed that, with increasing sand relative density and surface roughness of the pile material, the shaft friction resistance of the model pile increases. A back-calculation analysis was also performed to find the values of lateral earth pressure coefficient (K) using Burland’s (1973) equation with the help of measured shaft friction capacity of the model pile load test. By performing multivariate regression analysis, an equation was obtained between the back-calculated lateral earth pressure coefficient (K) and other parameters. The obtained equation was used to calculate the K values given in other studies in the literature. It was determined that the obtained equation was in good agreement with the data in other studies. This equation can be beneficial in practice and can be advantageous for further study in the future.

Dopamine-Mediated Biopolymer Multilayer Coatings for Modulating Cell Behavior, Lubrication, and Drug Release.

Biopolymer coatings on implants mediate the interactions between the synthetic material and its biological environment. Owing to its ease of preparation and the possibility to incorporate other bioactive molecules, layer-by-layer deposition is a method commonly used in the construction of biopolymer multilayers. However, this method typically requires at least two types of oppositely charged biopolymers, thus limiting the range of macromolecular options by excluding uncharged biopolymers. Here, we present a layer-by-layer approach that employs mussel-inspired polydopamine as the adhesive intermediate layer to build biopolymer multilayer coatings without requiring any additional chemical modifications. We select three biopolymers with different charge states─anionic alginate, neutral dextran, and cationic polylysine─and successfully assemble them into mono-, double-, or triple-layers. Our results demonstrate that both the layer number and the polymer type modulate the coating properties. Overall, increasing the number of layers in the coatings leads to reduced cell attachment, lower friction, and higher drug loading capacity but does not alter the surface potential. Moreover, varying the biopolymer type affects the surface potential, macrophage differentiation, lubrication performance, and drug release behavior. This proof-of-concept study offers a straightforward and universal coating method, which may broaden the use of multilayer coatings in biomedical applications.

ANALYSIS OF FLOW AND TEMPERATURE DISTRIBUTION IN JOURNAL BEARING LUBRICATED WITH VEGETABLE OIL

The use of vegetable oil as a sustainable alternative to mineral oil in lubrication applications has garnered considerable attention. This research focuses on evaluating three different vegetable oils, namely palm mid olein (PMO), refined bleached deodorized palm oil (RBDPO), and rapeseed oil, for their effectiveness in lubricating a hydrodynamic journal bearing. The study examines key performance factors such as pressure, temperature, load-carrying capacity, and coefficient of friction. Computational fluid dynamics (CFD) is employed to compare the lubricating capabilities of the vegetable oils against engine oil. Rapeseed oil emerges as the most promising option among the vegetable oils, displaying notable advantages. It demonstrates a 22.12% higher pressure, 26.37% higher load-carrying capacity, and 0.37% higher temperature distribution compared to PMO. In contrast, while engine oil exhibits a 16.67% higher pressure distribution and 35.8% higher load-carrying capacity, it also comes with a drawback of 44.29% higher coefficient of friction compared to other vegetable oils. It is worth noting that the simulation results have been validated through experimental data, leading to the conclusion that engine oil surpasses vegetable oils in terms of pressure and temperature distribution.

Design charts and equations of the frictional resistance of single pipe pile under static and seismic loads

Foundations can be exposed to seismic loads in addition to static loads in seismic active areas. Thus, it might be necessary in this situation to use deep foundations rather than shallow foundations in order to prevent bearing capacity failure, improve the system’s dynamic stiffness, and/or minimize dynamic oscillations. In a seismically active area, the pile designer is expected to obtain at least the maximum earthquake-induced frictional resistance of the pile in order to achieve the necessary strength to ensure the structural integrity of the pipe pile is not compromised. However, determining the frictional resistance of the pipe pile is considered challenging. Therefore, in this study, design charts and new equations have been proposed to provide straightforward means to the designers to predict the frictional resistance of pipe piles embedded in dry and saturated cohesionless soils. The proposed charts and equations are for closed ended (CE) and open ended (OE) pipe piles. The charts have been developed based on the results of a validated three-dimensional finite element analysis. In addition, the equations were developed using regression analysis, where a high coefficient of correlation values is obtained (ranging between 0.94 and 0.98). The proposed predictive tools could assist designers in preliminary checks of the frictional capacity of pipe piles in seismic active areas.