Increase In Bearing Capacity Research Articles

Synchronization of the yield as a way to increase integrity and bearing capacity of the frame supports

ABSTRACT The purpose of this research was to provide structural integrity, increase the bearing capacity and safety of the yield frame supports used in heavy underground conditions. Actual measurements in situ, loading of the frames by testing machine, physical modelling and thermodynamics of irreversible processes verified that the frame clamps yield asynchronously, by turn, each after other in the conventional frame supports that cause their blocking, jamming and destroying. Connecting the opposite clamps with a flexible element synchronizes the yield of the opposite fasteners and prevents their failure. Coherent behaviour of the clamps increased bearing capacity of the frames by factor 1.73.

Pravci razvoja i primene plazma nitriranja u industriji

This paper presents a discussion of the results of previous research of the effects of surface modification of structural materials and tool steels using plasma nitriding (PN) in order to improve their mechanical, tribological and corrosion behavior. The paper discusses the current status and future directions in the application of PN on various wearing components that are exposed to high loads, stresses and frequent temperature changes. The paper provides an overview of the relevant literature whose results show the most favorable or optimal parameters of the PN process aimed at achieving the best performance in terms of wear and corrosion resistance and hardness increase for the various materials considered. Systematization of literature data about research of the impact of low-temperature PN on stainless steels has placed emphasis on those process mechanisms that achieve benefits for surface layers without creating negative side effects in the form of loss of corrosion resistance. The strengthening of hot forging dies is considered through the reasons and problems that cause the need for the application of PN, and then paper focuses on the role of PN in achieving the tribological properties required to extend the service life of the die. Publications in which the nitriding of titanium alloys is investigated through the reduction of wear, increase of bearing capacity and microhardness depending on the input parameters of the process, ie the optimal parameters applied in order to obtain the best performance characteristics are cited. The application of PN to aluminum and its alloys is discussed, as well as the conditions of testing and the achieved improvements.

Flexural behavior and finite element analysis of waste tires steel fiber reinforced concrete beams with basalt reinforcement

Waste Tire Steel Fiber(WTSF) was used in different proportions (0%, 0.5%).1% and 1.5%) were mixed with ordinary concrete to produce WTSF reinforced concrete. Based on basalt fiber reinforced polymer and WTSF concrete, a new structural system, WTSF concrete beam with basalt reinforcement, is proposed. On the basis of the theory test, using the ABAQUS finite element software to simulate basalt rebar waste of the bending properties of steel fiber concrete beam, to obtain the stress nephogram, cracking load, ultimate bearing capacity, load deflection curves and crack location map, comparative tests and fitting results show that WTSF volume content 0% less muscle damage, 0.5% for balance, 1% and 1.5% are superreinforced failure. With the increase of WTSF content, both cracking load and ultimate bearing capacity are improved. Meanwhile, theoretical calculation formulas of relevant components are given to guide engineering practice.

COMPRESSIVE CAPACITY OF HELICAL PILE FOUNDATION ON PEAT WITH VARIATION OF HELICAL PLATE DIAMETER

<p>The use of helical foundations to support structures on peat soil is still a new method. Research is needed to develop this foundation. There are 6 types of helical foundation tested on peat soil. To study the effect of helical plate diameter, plate diameters were varied with sizes 25 cm (M), 35 cm (L), and 45 cm (G). Plate positions (1, 2, 3 plates) are designed at 300 mm spacing. The axial compression bearing capacity test is carried out based on the constant rate of penetration procedure. At the beginning of loading, the load increases significantly. At a certain descent, the load begins to decrease slowly. The load-settlement curve shows that the larger the plate diameter, the greater the load it can withstand. The largest bearing capacity is produced by the GGG 30 foundation (3 plates dia.45 cm), which is 10.83 kN. LLL 30 helical foundation (3 plates dia.30 cm) provides a bearing capacity of 7.14 kN. These results clearly explain that the increase in plate diameter is directly proportional to the increase in the axial compression bearing capacity.</p>

Development of Single-Phase Microbial Cementation Method and to Investigate its Efficacy on Bearing Capacity, UCS, and Permeability of Sandy Soils

Microbially induced calcite precipitation (MICP) is a method based on collaborative knowledge of microbiology, chemistry and geotechnical engineering. The objective of this study was to investigate the increase of the bearing capacity and the unconfined compressive strength (UCS) as well as the reduction of the permeability of sandy soil using MICP. Experiments were carried out using Bacillus Pasteurii, on three different types of sand. The admixture of bacterial culture and cementation (BCC) solution all-in-one with sand by single-phase injection was applied to induce cementation. Three samples of the selected sand were treated with varied concentrations of BCC solution, ranging from 0.05 to 0.2 L/kg, with a curing period of 3, 7 and 14 days. The test results indicated an enhancement of 55% in UCS for sand treated with a BCC content of 0.05 to 0.2 L/Kg and a reduction of 40% in permeability for untreated sand with an effective diameter of 0.5 mm treated with 0.2 L/kg of BCC solution after 14 days of curing. The results of a plate load test (PLT) on MICP treated sand showed an increase in the ultimate bearing capacity (qu) by about 2.95 to 5.8 times and a 1.7 to 3.31-fold reduction in settlement corresponding to the same load applied on untreated footing. Further investigation of the size and shape of the bearing plate on bearing capacity and settlement was carried out through a plate load test. The higher and more favorable results shown by a rectangular plate compared to a circular plate indicate that the first is preferable.

Comparison between Theoretical and Experimental Behavior of Shallow Foundation in Cohesive Soil

This paper discusses a finite element analysis of shallow footing subjected to axial loading rested on different types of cohesive soil by using a computer program called PLAXIS-3D (V.20) software. The behavior of cohesive soil is simulated using several constitutive models (Mohr-Coulomb model, Hardening soil model, and Hardening soil with small strain stiffness model in order to find the best match between theoretical and experimental results).Two cases are considered square and rectangle. Moreover, some parameters that affect the load settlement relation curve; such as internal friction angle and soil modulus elasticity were investigated. It was found that the simulation by the Hardening soil model with small strain stiffness gives better results in both cases of the square and rectangle (C=25) and square footing (C=70). It was also observed that increasing the foundation width led to increases in bearing capacity, however, there was an increase of bearing capacity to about (9.45 %) for an increase in footing width of (6.25), so it was about (17%) for (12.5). For square footing in stiff clayey soil, the bearing capacity of the soil increases to about (23%) when the range of the modules of elasticity of soil increases from (10000 to 30000KN/m2).

Seismic design method and plastic hinge of square steel tube confined reinforced concrete (STRC) columns

Steel tube confined reinforced concrete columns have the advantages of high bearing capacity, good ductility and convenient construction, which meet the requirements of "building industrialization", so they are widely used in high-rise buildings. Based on the plastic-damage constitutive model of concrete and elastic-plastic mixed strengthen constitutive model of steel, finite element software ABAQUS was used to build an elaborate 3D finite element solid model and perform pseudo-static analysis of square steel tube confined RC(STRC) columns. The model considered the confinement effect of the steel tube exerting on the core concrete, as well as reasonable boundary conditions and loading modes. Good agreement was achieved between the finite element analysis results and the existing quasi static experimental results regarding to the failure modes, load-displacement hysteretic curves and load-displacement skeleton curves. Based on the validated model, 136 full scale model examples were established and extensive parametric analysis was conducted. The results show that the confinement of external steel tube can reduce the peak compressive strain and increase the peak compressive stress of concrete, thus delaying the failure of RC column and improving its bearing capacity and ductility effectively. Besides, the failure displacement angle and ultimate bearing capacity increase when the thickness of steel tube increases. Finally, the seismic design method including reasonable thickness and hoop index of the steel tube were proposed for 5 material strength matching and different axial compression ratios. A method to judge the plastic hinge based on concrete strain and steel tube strain was proposed, as well as a practical calculation formula of plastic hinge length. This study can provide basis and support for the seismic design of frame columns.

Behavior of CFRP-confined Concrete-filled square steel tube columns with section circularized under axial compression

Eight carbon fiber-reinforced polymer (CFRP)-confined concrete-filled square steel tube (CFSST) specimens and twelve CFRP-confined CFSST specimens with section circularized were tested under axial compression to investigate the effect of different loading conditions and CFRP layers on axial compressive behavior of CFRP-confined CFSST columns with section circularized. Experimental results indicated that section modification method (circularization) improves the CFRP confinement and increases bearing capacity of CFSST columns. Meanwhile, the effect of CFRP layers on the bearing capacity of CFSST columns is also evident. Combination models of Han–Lam & Teng and Mander–Pham & Hadi are suggested in this study for calculating the bearing capacity under different loading conditions. Results showed that predictions are consistent with the experimental results.

Study of Improving Soil Using Permit, Corn Ash and Sodium Silicate

Soil that has low bearing capacity has a bad impact on the construction that is built on it as a result of which the building is easily damaged such as lifting the foundation on the building and causing cracks and shifting on the road. This research uses experimental laboratory methods. Soil samples used were taken from Lembang Tondon Siba’ta, Tondon District. Corn cobs were taken from Sa’dan Marante, Sodium silicate is obtained from chemical figures and palm fiber taken from Buntu Tagari and then tested for soil physical characteristics and soil bearing capacity in soil samples with a mixture of sodium silicate, corncob ash, palm fiber and soil without mixture. know the bearing capacity of the soil. The results of the research on stabilized soil by adding 0.2% palm fiber, 2% corncob ash and 3% sodium silicate obtained an increase in soil bearing capacity of 9.73% from the original soil and the addition of 0.2% palm fiber, 4% corncob ash and 3% sodium silicate.

Effect of several patterns of floating stone columns on the bearing capacity and porewater pressure in saturated soft soil

One of the common geotechnical problems is the construction on soft soil and the improvement of its geotechnical properties to meet the design requirements. A stone column is one of the well-known techniques used to improve the geotechnical properties of soft soils. Sometimes thick layers of soft soil imposed the designer to use floating stone columns for improvement of such soil; in this case, the designer will be lost the end bearing of the stone column. In this study, the effects of several patterns of floating stone columns distribution under footing on the bearing capacity of soil and the distribution of excess porewater pressure are investigated. The soft soil used in this study has a very low undrained shear strength (cu) of 5.5 kPa and improved by several patterns of stone columns (single, two linear, triangular, square, and quadrilateral). The stone column has a length of 180 mm and a diameter of 30 mm. The material of the stone column is poorly graded sand has an angle of internal friction (48.5°) at a relative density of 65%. The results indicated a significant increase in the ultimate bearing capacity of soft soil when treated with floating stone columns despite the small ratio of area replacement and reducing the excess porewater pressure and settlement. Also, the ultimate bearing capacity of soil calculated from experimental work is compared with the corresponding values obtained from the proposed equations in the previous studies to evaluate the validity of using such equations.

FIELD STUDY ON SOFT SOIL IMPROVEMENT USING CONTINUOUS FLIGHT AUGER (CFA) PILES

The continuous flight auger (CFA) piling technique is commonly used where the presence of groundwater or potentially collapsible material reduces the cost-effectiveness of bored piling techniques. Whilst generally considered a soil replacement technique, the process of pumping concrete under pressure during the pile installation can result in a significant improvement of the surrounding soil, particularly in low strength soil conditions. In this study, a case study is analyzed. An oil storage tank was intended to be constructed on soft clay in southern Iraq. The tank has a diameter of 46 m. Cone penetration test, drilling boreholes, and field tests have been conducted in the tank site. A decision was made to improve the mechanical properties of soft clay of the site by CFA piles before construction of the tank. The depth of CFA pile constructed is 16 m, with a diameter of 0.5 m and spacing between piles is 4.2 m. Three types of in-situ tests have been conducted: Conventional plate load test on the soil before and after improvement; large plate load test for soil after improvement; and pile load test on CFA pile. It was concluded that construction of CFA piles shows an increase in the bearing capacity by about 110% for the soil directly around piles and 70% for soil within 2 m from the center of piles. Large plate load test result for the pile with surrounding soil revealed that the ultimate bearing capacity increases to 500 kN/m2. So that the overall loading area showed an increase in the bearing capacity of about 350% when CFA piles are constructed.

Numerical study of cold-formed steel frame walls under compression loading

Bearing walls in cold-formed steel buildings act as a transmitter of vertical loads of the building and as a retainer of the exterior of the building and also absorb the lateral loads of the building such as wind and earthquake loads. In this article, the behaviour of cold-formed steel frame walls under compressive axial load has been investigated numerically. First, the finite element model of the cold-formed steel wall was developed using ABAQUS software, and then, structural analysis was performed, taking into account the effects of geometric and materials nonlinearities. The results of the numerical model were compared with the experimental results to confirm the accuracy of the numerical model. In the following, parametric studies have been carried out considering some parameters affecting the behavior and the ultimate load of cold-formed steel frame walls such as type of sheathing, stud web depth, stud flange width and stud cross-section shape. The results of the structural analysis showed that the type of wall sheathing did not have a significant effect on the ultimate load of the wall, but increasing the web depth of the stud, has led to a decrease in the load-bearing capacity of the steel wall. The wall with hollow flange studs has a higher ultimate load than other sections, and also, the use of web stiffened stud leads to an increase in the final bearing capacity of the wall compared to typical sections.

Pressure Settlement Behaviour and Bearing Capacity of Asymmetric Embedded Plus Shaped Footing on Layered Sand

The aim of the present numerical study was to analyse the pressure settlement behaviour and bearing capacity of asymmetric plus shaped footing resting on loose sand overlying dense sand at varying embedment depth. The numerical investigation was carried out using ABAQUS software. The effect of depth of embedment, friction angle of upper loose and lower dense sand layer and thickness of upper loose sand on the bearing capacity of the asymmetric plus shaped footing was studied in this investigation. Further, the comparison of the results of the bearing capacity was made between the asymmetric and symmetric plus shaped footing. The results reveal that with increase in depth of embedment, the dimensionless bearing capacity of the footings increased. The highest increase in the dimensionless bearing capacity was observed at embedment ratio of 1.5. The increase in the bearing capacity was 12.62 and 11.40 times with respect to the surface footings F1 and F2 corresponding to a thickness ratio of 1.5. The lowest increase in the dimensionless bearing capacity was observed at embedment ratio of 0.1 and the corresponding increase in the bearing capacity was 1.05 and 1.02 times with respect to the surface footing for footings F1 and F2 at a thickness ratio of 1.5.

Improvement of Soft Clay Soil Using Different Types of Additives

This study deals with the evaluation of the stabilization of several samples of soft soil with some chemical and physical additives. The intention is to amend the weak properties of these soils summarized in low bearing capacity and high settlement. The used stabilizers are quicklime, class F fly ash activated by cement, rock powder, crushed waste concrete, and tire crumb rubber. The paper investigated the effects of these stabilizers by unconfined compression test that considers very effective geotechnical test for measuring the ability of soils to bear structures constructed on them especially when used additives. This test was carried out on three samples of soils. They were classified by (UCSC) as (CL) soft soils. They were also classified by (AASHTO) as (A-7-6), (A-6), and (A-6) are rated as fair to poor subgrades in (AASHTO). The results of (UCS) test for each of the five additives used were compared according to the responding of each soil samples used. The (UCS) test was conducted in this study on sixty samples of soils before and after treatment and under the basics of the Proctor compaction test at optimum moisture content and maximum dry density. The results showed that the rock powder was the most suitable stabilizer that gave best results of improvement reached to 900% at 25% percent by dry weight of soil, crushed waste concrete came after it that gave treatment 683% at 15%, class F fly ash activated by cement followed the two formers which increased strength 533% at 15%, quicklime after that in an amendment 517% at 9% and finally tire crumb rubber that stabilized the soil 500% at 4%. In the literature, these materials founded to be very efficient in the stabilization of soils in their physical and chemical properties like increasing bearing capacity and reducing settlement of soil.

Impact of Inclined Load on the Performance of Under-Reamed Piles in Clay Soil

This research aims to study the behavior of under-reamed piles under the influence of inclined loads. Four piles of length 350 mm, 20 mm in diameter containing (0, 1, 2, and 3) of bulbs each one has 40 mm in diameter used, and they were inserted into stiff clay and sandy soils (CH and SP) so that the end of the pile sits on dense sandy soil, and the ultimate load capacity of the pile was calculated. The bearing capacity increase reaches more than 76% due to the presence of bulbs in a pile, and the increase reaches after there are two bulges to 15%. The lateral displacement of the pile was also studied by using the lateral load and the compound load and on four stages of the allowable load. The results showed that the effect of the compound load is limited in the normal pile, but in the under-reamed pile, the higher the vertical load, the less the lateral displacement. As for the moments resulting from the combined loads, the effect was up to 10% in the presence of an inclined load compared to the lateral load, and the effect of the presence of bulb in a pile near the ground level appeared to reduce the moments generated for the same load.

SOME PECULIARITIES OF THE INSTALLATION, DESIGN AND CALCULATION OF HINGE BOLT CONNECTIONS IN THE FLOWS OF STEEL DOUBLE BEAMS IN THE RECONSTRUCTION OF BUILDINGS

Formulation of the problem. The object of study is steel beams of technological sites and coatings of buildings under static load. Statically indeterminate beams of the 1st class (according to the classification given in DBN B.2.6-198:2014) are considered, for which as a result of the reconstruction of the building provided in the project, increase in intensity of loading increase of bearing capacity of beams is required. The analysis of the existing ways of increase of bearing capacity of beams without strengthening by a method of increase in cross sections, namely, vertical movement of supports of a beam, the device of artificial hinges in beams of a beam is resulted. These methods allow the adjustment of the forces in the beam so that the bending moments in the run and the support section are the same in absolute value, which is less than the maximum bending moment in the beam before the adjustment of the forces. The problem is the design of the bolted hinged connection of the suspension beam with the cantilever beam without dismantling the beam stored for further operation, or without the installation of temporary supports in the joint area. The purpose of the article. Identify and take into account the features of the location, calculation, design and execution of hinged bolted joints in the beams saved for further operation of the beams without their dismantling. Conclusion. The design of the hinged bolted connection of the suspended beam with the cantilever has been developed. The walls of the suspension and cantilever beams are connected so that on one side of the joint the bolts are located in one vertical row, which provides free rotation of the cross sections of the suspension and cantilever beam with sufficient, determined by calculation, the difference between the diameters of holes and bolts. One vertical row of bolts should be placed in the wall of the suspension beam, for the strength of the bolted connection of the pads. An example of construction and calculation of a hinged cantilever beam formed from an integral two-span beam during the reconstruction of the building is given.

Experimental investigation on axial compression behavior of laminated bamboo lumber short columns confined with CFRP

In order to study the axial compression behavior of short columns confined with carbon fiber reinforced polymers (CFRP), 21 specimens were tested under monotonic loading. Four failure modes were classified based on the test results which were adhesive layer failure, compression failure, buckling failure and local buckling failure. With the improvement of external reinforcement effect, the failure mode changed from compression failure to buckling failure or local buckling failure. With the increase of cloth ratio, the ductility and ultimate bearing capacity of the specimens increased, but not linearly. However, the increase range gradually decreased even the cloth ratio kept increasing. When the cloth ratio reached 2.56%, the ductility reached the maximum. The lateral deformation of laminated bamboo columns was restricted by CFRP during compression, thus lateral strain and Poisson's ratio gradually decreased with the increase of cloth ratio. Stress–strain model and formula for calculating the compressive strength of reinforced columns were proposed which gave a good agreement with the test results.

PENURUNAN OPRIT JEMBATAN SEMARANG LINGKAR UTARA DAN JEMBATAN KALI JAJAR DEMAK JAWA TENGAH DENGAN PRE-FABRICATED VERTICAL DRAIN

Construction on soft soil, often creates problems. The Semarang North Ring Bridge and Kali Jajar Bridge are the Recent soft Marine Alluvium zones located in the Pantura area which have very soft soil characteristics with a depth of more than -30.0 meters this has resulted in a very large settlement due to very small grains, flood, rob, pore water pressure increases so that the shear strength of the soil will be small, the compression is large and the permeability coefficient is small so that if the construction load exceeds the critical bearing capacity, the damage to the foundation soil will occur. To get the increase in soil bearing capacity, it can be achieved by changing the properties of the soil from the shear angle (f), cohesion (c) and unit weight (g). The settlement can be reduced by increasing the cavity density from the compression of the soil particles (Wesley, 1977). Soil improvement takes a long time, aiming to increase shear resistance so that it requires a fast time in this case is to use Pre-Fabricated Vertical Drain (Bowles 1981). The results of the analysis of the pattern of decline and the effectiveness of the use of PVD (pre-fabricated vertical drain) at the Oprit Bridge in the two research locations have the same decrease in the range of the same heap height at (H = 4 meters) there is a decrease of 117.53 cm at 64 months on the bridge. Kali Jajar (STA. 3 + 200) and there was a decrease of 268.94 cm at 37 months at the Semarang North Ring Bridge

Performance Evaluation of CFRP Strengthened Corrosion-Proof Columns

The application of FRP composites in recent years has attracted much attention. Lightweight, high strength, and corrosion resistance are among the properties that make this material available in various forms in construction engineering. The present study analyzed the performance of carbon fiber-reinforced accelerated corrosion-proof box. Nine columns without corrosion and cross-corrosion reinforcement were tested in laboratory and software. Syntax reinforcement was applied locally to the damaged area with respect to a transverse and longitudinal layer. The results of the axial test showed that, due to corrosion, the damaged site was weakened by the loading and severe resistance decreased, and the range of damage points due to the axial load was highly deformed compared to the initial state. The damage caused on both sides of the steel column had a significant effect on reducing the hardness and deformation of the steel columns; it is worth noting that the corrosion on both sides of the steel column had the most variations among the samples. Application of CFRP with 2 layers in the damaged steel columns resulted in increased bearing capacity and hardness in the affected area due to corrosion so that reinforcement of these columns by carbon fibers improved the axial strength.

A study on the vertical bearing capacity according to the inclination angle of single batter piles and the relative density of sand under vertical loads

This study analyzed the increase in the compressive bearing capacity of single-sloped piles according to the relative density and inclination angle when the batter piles are subjected to a vertical load in non-adhesive sand. An experiment was conducted with inclination angles of 0, 10, 20, 30, and 40, and the relative density of sandy soil was divided into 31% (loose), 53% (medium), and 72% (dense) and compared with the results of the earlier research. As a result of the experiment, when the relative density of the ground was medium and dense, the bearing capacity was greater than that of the vertical pile (0°) at all angles. The tendency noted was that the bearing capacity of the pile increased from vertical to 20° and gradually decreased after 20°. The same tendency was also exhibited by loose sandy soil, but with less bearing capacity than the vertical pile (0°) except for 20°.