Load Test Method Research Articles

Tegangan Ambang pada Sambungan Las CDW antara Baja dan Kuningan dalam Lingkungan Korosif

Failure at the welded joint can be occurs due to the Stress Corrosion Cracking (SCC) phenomenon. Dissimilar welding is more susceptible to SCC when compared to similar welding. This can be occurs because the material or metal that connected is non-homogeneous material. which causes the material will be difficult to be combined perfectly. This study aims to determine the threshold stress (σ Th ) at the dissimilar welded joint between steel and brass which have SCC loads. Both materials were connected by the welding method by using a Capacitive Discharge Welding (CDW) welding machine. Surface preparation or surface treatment is applied to one of the basic materials (low carbon steel) to obtain optimal joint results. The welded joint was tested by using Constant Load Test (CLT) methods, which is engineered in such a way that the welded joint get the stress, corrosive environment (1M NHO 3 solutions) and voids produced by the weld joint itself. The result shows that the threshold stress of the dissimilar welding joint between steel and brass by the CDW method is 330 MPa.

Evaluation of Full-Scale Concrete Frames Exposed to Natural Fires at Early Ages.

This article presents the evaluation of full scale reinforced concrete frames subjected to natural fire at early age. The test program consisted of constructing three large frames of reinforced concrete as well as revealing them to the natural fire by shooting their formwork when the age of concrete achieves three and five days. The evaluation of reinforced concrete frames was done by the load test method as described in the American Concrete Institute (ACI), namely the 24 hrs load test method, which is evaluation criteria that have been in use for several decades. For each frame, the structural evaluation based on deflection criteria is discussed. Results showed that the frame exposed early to natural fire was generally more affected than the other frame, as its midspan deflection was increased to about 109% if compared to frame not exposed to fire.

Analysis of Carrying Capacity of the Bored Pile Foundation in Cibubur Transpark Project

The foundation is a construction that continues the burden of the upper structure and passes it on to the soil below it. A bored pile foundation is now an option in working on structures in densely populated areas and tall buildings. The purpose of this study is to calculate and compare the carrying capacity of the bored pile foundation based on N-SPT data with the O 'Neil & Reese, and Reese & Wright methods, while the Loading test data with the interpretation of the Davisson method and the Mazurkiewicz method. The results of calculations based on N-SPT data, the average ultimate carrying capacity of the foundation with the O’neil & Reese method of 1211.61 tons, Reese & Wright of 1235.02 tons. While the Interpretation of Loading test method for Marzukiewicz is 1267.00 tons, Davisson is 850.40 tons, and the carrying capacity of PDA test results is 121.72 tons. From the calculation of the bearing capacity of the consecutive foundation of the smallest is the Davisson method, the O'neil & Reese method, the PDA test method, the Reese & Wright method, and finally the Mazurkiewicz method.

Research on the Dynamic Mechanical Properties and Constitutive Models of Steel Fiber Reinforced Concrete and Polypropylene Fiber Reinforced Concrete

This paper presents the results of an experimental research designed to investigate the dynamic mechanical properties and constitutive model of fiber reinforced concrete (FRC), including steel fiber reinforced concrete (SFRC) and polypropylene fiber reinforced concrete (PFRC) under fast loading. Experimental results are achieved by using the electrohydraulic servo loading test method, implying that the dynamic mechanical properties of PFRC and SFRC, such as peak stress, peak strain, and toughness, are positively affected by strain rate. The experimental elastic modulus test results of FRC with different fiber contents indicate that the elastic modulus is positively affected by polypropylene or steel fibers and increases with the increment of fiber content. Finally, the experimental stress‐strain curves obtained in the MTS electrohydraulic servo system test are fitted by a damage dynamic constitutive model of FRC. The good fitting with experimental results proves that the model could be appropriate to describe the dynamic mechanical properties of FRC.

A Comparative Analysis of Foundations using Prescriptive Design and Static Loading Test Methods

A Comparative Analysis of Foundations using Prescriptive Design and Static Loading Test Methods

A review of neck injury and protection in vehicle accidents

Abstract Neck injury is one of the most common types of injury in vehicle accidents. The mechanisms of neck injury remain controversial due to the complex structure of the cervical spine and various impact conditions. The aim of the present study is to provide a summary of recent research on neck injury mechanisms, neck injury criteria and neck injury prevention measures. The main types of neck injury resulting from vehicle accidents, including whiplash injury, cervical bone fractures and spinal cord injury, are introduced. Neck injury mechanisms are summarized according to load directions, test or simulation methods, and thresholds by means of impact intensity, load intensity and stress/strain conditions. Neck injury criteria are introduced, including NIC, Nij, Nkm and LNL. Passive and active technologies for neck injury prevention are described and the challenge of neck injury prevention for future intelligent vehicles is discussed.

Probability distributions of mechanical properties of natural aggregates using a simple method

Characterizing the strength and the elastic modulus of single aggregate particles is relevant, in particular for use in high-strength concrete. One problem of methods normally used in this task is the time and effort demanded. The work proposes a rapid and simple test method to measure the probabilistic distributions of those properties for coarse aggregates contained in the range of particle sizes between 9.5 and 25-mm, approximately, applying it to granite and limestone. Water absorption (WA) of a hundred individual particles of each type of coarse aggregate was measured. Afterwards, the Point Load Test method is used to determine the tensile strength of all particles. A Linear Variable Differential Transducer (LVDT) coupled to the mechanical essay measured the displacements, under Hertz contact conditions, between artificially flat-made irregular particles and the testing machine fixture, allowing to determine the elastic moduli. Results were represented using the Weibull probabilistic distribution function. The one hundred individual particles, when stratified on the basis of non-destructive WA measurements, allowed capture the mechanical variability in the data. As such, mechanical tests could be performed only with approximately 20 specially selected particles of each aggregate type. Fundamental inverse exponential functions between the mechanical properties and WA confirmed the possibility of using this artifice. The tensile strengths ranged from 3 to 22 MPa for granite aggregates and from 3 to 16 MPa for limestone aggregates. Elastic moduli of the aggregates were also variable: 18–78 GPa for granite aggregates, and 18–66 GPa for limestone aggregates. Values within these ranges may influence the mechanical performance of high strength concretes.

In situ estimation of equivalent porosity and strength of aluminum die-casting floor panel by simple loading test and finite element method

A simple estimation method of equivalent porosity and strength of scrapped aluminum die-casting floor panel is suggested in which various defects like pores can be allowed. During shop practice of processing die-casting parts, equivalent porosity is evaluated by the ratio of linear stiffness from the simple test to the analytical stiffness value. Porosity equation is derived from the inclusion theory. Then using Mori-Tanaka method the porosity value is used to find an elasto-plastic stress-strain curve for the porous material. In this paper Hollomon equation is used to describe the strain hardening effect of the die-casting material. Finally, the stress-strain curve for the porous material is used to calculate strength of die-casting part that captures the nonlinearity of the porous material. A facility die-casting floor panel is chosen to verify the proposed method. The result is accurate and adequate to the test result.

Andesite, Construction material, Kulon Progo , Yogyakarta, Indonesia.

The construction projects that are currently being carried out in Kulon ProgoRegency, Yogyakarta Special Province, Indonesia, started on 2018, are large-scale projects. The projects include the construction of airports, seaports, industrial estates, southern crossing lanes and the construction of Menoreh lanes. The large-scale projects require a very large supply of andesite rocks for material construction. In Kulon Progo Regency itself, there is a huge potential of andesite rock relate to two geological formations (Kebo Butak and Andesite Intrusion) exist in the region, which is found mostly in Kokap District and partly in Temon District. One parameter that determines the quality of andesite rock is their compressive strength. Due to weathering, not all of the andesite in both formation can be classified as good quality rocks. According to Indonesian Standard, theminimum compressive strength of natural stone for stakes and curbstone is 500 kg/cm2 , for lightweight building foundation is 800 kg/cm2 , for medium building foundations is 1000 kg/cm 2and for heavy building foundations is 1500 kg/cm 2 . Based on this background, this paper have objectives to know the quality of andesite rock exist in the research area and to determine the zonation of good quality andesite rock for building androad materials in the research area. Field observation were conducted to map the occurrence of andesite rock. Totally 68 rock samples were collected during field observation and tested by point load test method to know its compressive strength value. The distribution of good quality rock in the research area were determine based on spatial analysis procedure in geographical information system. Results show that andesite rocks found in research area have a compressive strength ranging from 167.12 kg/cm 2 to 2783.37 kg/cm 2 . From 53 samples taken from igneous rock intrusion, it showed that 7.55 % had low quality, 13.21 % had medium quality, 30.19 % had good quality and 49.06 % had very good quality. From the 16 samples taken from the Kebobutak Formation, it showed that 12.50 % had low quality, 18.75 % had good quality and 67.75 % had very good quality. The final map of rock quality zonation reveals 28.92 % of research area classify as low quality, 2.52 %medium quality, 37.68 % good quality and 30.88 % very good quality. It can be concluded that almost 70 % of andesite in the Kokap and Temon District can be used for the running large scale projects.

Double layer load cell test of self-balanced method for bearing capacity of super-long bored piles

The large diameter super-long bored pile’s bearing capacity is generally very high. The self-balanced method is a new type of static load test method, and it is suitable for the test. At Yueqing Bay No. 1 Bridge, a pile with diameter of 2500 mm and length of 112.0 m was discussed in detail. The post grouting technology at pile bottom was used. The self-balanced method was carried out before and after post grouting. The double layer load cell test method was introduced. The ultimate bearing capacity of the upper, the middle, and the lower part piles were obtained. The test results were converted to the traditional top-down method. The ultimate bearing capacity before grouting was 46932 kN, and it was 70680 kN after grouting. The increment percentage was 50.6%.

Application of static loading tests to steel pipe piles with large diameters in Chinese offshore wind farms

In this paper, three kinds of static loading test methods were introduced by referencing three offshore wind farms in China. In the first project, O-cell tests were performed on four steel pipe piles, namely, two vertical piles and two inclined piles, with diameters of 1.7 m and embedment depths from 67.24 to 69.70 m. Next, the equivalent load-settlements for top-down load and pull-out load tests at the pile heads were given by using a conversion method. Then, the conversion results were verified using different methods. Finally, the rationality of utilizing the coefficient factors of γ1 and γ2, which were 0.8 and 1.1 in the first project, were verified by studying three piles in two other offshore wind farm projects, where a top-down load test and pull-out load test were conducted on each pile. The results show that the O-cell test can successfully determine the axial compression capacity and uplift capacity by the proposed conversion method.

Comparison of Single and Group Jet Grouting Columns Capacity Based on Field Load Test and Theoretical Methods

The evaluation of axial capacity of jet grouted soil cement columns in soft soil is a complicated issue because it depends according to the number of factors such as, soil type, influence mixture between soil and grouting materials, nozzle jet energy, jet grouting and water flow rate, rotation and lifting speed. These parameters related to the type of jet grouting methods (single, double and triple system). Most methods of design the bearing capacity of the jet-grouting column based on experience. Therefore, some designer calculates the bearing capacity of the jet grouting column based on jet grout section capacity. In this paper, different theoretical methods have been used to estimate of the jet grouting soil-cement capacity, such as Poulos and Davis, 1980 methods and then their comparison with the pile load test calculations based on the quick pile load test as presented in ASTM-D1143-07. Therefore, the study describes a prototype test single and group jet grout soil-cement models of arrangement (1*1, 1*2 and 2*2) for total length to diameter ratios (L/D) is 13.33 and clear spacing three times of diameter has been constructed in soft clayey soils in the right bank of the Euphrates River, at Al- Nasiriyah city. As a result, the theoretical method for estimation the bearing capacity gives unfaithful values for the single and group jet grout column compared to the load- settlement calculations obtained from field pile load test data. On the other hand, the Hansen’s 90% and Butler and Hoy’s given closer results to each other and may be considered faithful interpretation methods to compute the bearing capacity of single and group jet grouting columns.

Feasibility investigation of the mechanical behavior of methane hydrate-bearing specimens using the multiple failure method

The multiple failure test method is an efficient compress test method for studying the mechanical properties of rock. The method can use one sample to obtain the main mechanical properties under different confining pressure conditions. To verify the feasibility of this method and to evaluate the damage mechanism in testing the mechanical properties of the methane hydrate-bearing specimen (MHS), an experimental apparatus has been designed to supply high-pressure and low-temperature testing conditions. The specimen was compressed successively under the confining pressure conditions of 2 MPa, 6 MPa and 10 MPa. The mechanical properties of MHS using the multiple failure test method can coincide well with the test results in the conventional single loading test method. The feasibility of using the multiple failure test method to study the mechanical behavior was verified based on experimental data. Furthermore, the damage mechanism of MHS was investigated by using a discrete element method with two test methods.

The role of point-of-care viral load monitoring in achieving the target of 90% suppression in HIV-infected patients in Nigeria: study protocol for a randomized controlled trial

BackgroundThe Joint United Nations Programme on HIV/AIDS 90–90-90 goal envisions 90% of all people receiving antiretroviral therapy to be virally suppressed by 2020. Implied in that goal is that viral load be quantified for all patients receiving treatment, which is a challenging undertaking given the complexity and high cost of standard-of-care viral load testing methods. Recently developed point-of-care viral load testing devices offer new promise to improve access to viral load testing by bringing the test closer to the patient and also returning results faster, often same-day. While manufactures have evaluated point-of-care assays using reference panels, empiric data examining the impact of the new technology against standard-of-care monitoring in low- and middle-income settings are lacking. Our goal in this trial is to compare a point-of-care to standard-of-care viral load test on impact on various clinical outcomes as well to assess the acceptability and feasibility of using the assay in a resource-limited setting.MethodsUsing a two-arm randomized control trial design, we will enroll 794 patients from two different HIV treatment sites in Nigeria. Patients will be randomized 1:1 for point-of-care or standard-of-care viral load monitoring (397 patients per arm). Following initiation of treatment, viral load will be monitored at patients’ 6- and 12-month follow-up visits using either point-of-care or standard-of-care testing methods, based on trial assignment. The monitoring schedule will follow national treatment guidelines. The primary outcome measure in this trial is proportion of patients with viral suppression at month 12 post-initiation of treatment. The secondary outcome measures encompass acceptability, feasibility, and virologic impact variables.DiscussionThis clinical trial will provide information on the impact of using point-of-care versus standard-of-care viral load testing on patient clinical outcomes; the study will also supply data on the acceptability and feasibility of point-of-care viral load monitoring in a resource-limited setting. If this method of testing is acceptable and feasible, and also superior to standard of care, the results of the trial and the information gathered will inform future scaled implementation and further optimization of the clinic-laboratory network that is critical for monitoring achievement of the 90–90-90 goals.Trial registrationUS National Institutes of Health Clinical Trials.gov: NCT03533868. Date of Registration: 23 May 2018. Protocol Version: 10. Protocol Date: 30 March 2018.

Tractors Hydraulics System Stress Testing Design and Experiment

This paper aims to research and analysis the tractor hydraulic suspension system stress. The hydraulics system was hooked on the latest developed hillside tractor chassis, this experiment used load test method and portable hydraulic testing instrument to test the cylinder movement process and force process. It can be concluded from the drawn curve that when the system loads 2940 Newton, the maximum working pressure is 4.4Mpa. When the system loaded 3920 Newton, the maximum load is 4.8Mpa. The pressure difference between the left and right levers is 2Mpa. The conclusion can provide data validation for the simulation analysis of tractor suspension system as well as an effective reference for the design scheme of tractor suspension system.

The Mechanical Performance of V150 Drill Pipe under Combined Tension-Torsion Loading

During the drilling of deep wells and ultra-deep wells, unsuitable tension-torsion coupling results to the failure of drill pipe. Therefore, it is necessary to study the combined tension-torsion resistant loading capacity of drill pipe. The combined tension-torsion loading test methods of pre-torsion followed by tension and pre-tension followed by torsion were used to analyze the interaction laws between the tensile stress/strain and torsional stress/strain of V150 drill pipe. It was found that during the pre-torsion followed by tension, both the preload shear stress and tensile yield strength were reduced; during the pre-tension followed by torsion, both the preload tensile stress and torsional yield strength were reduced. When material yielding occured, the tensile stress and shear stress were in accordance with the tension-torsion ellipse strength criterion, and the elastic deformation safety range of this tension-torsion ellipse strength criterion was 24.5% higher than that of von Mises strength criterion. The results showed that the combined tension-torsion resistant loading capacity of drill pipe designed according to the von Mises strength criterion was conservative to some extent, while the tension-torsion ellipse strength criterion included two benchmark parameters of tensile yield strength and torsional yield strength. Such criterion perfectly aligned with the experimental data and exhibited high engineering application value.

A Novel Incipient Evaluation Method for Postconstruction Settlement by Using a Statistic Approach with Time-Extended Loading Test

This paper proposes an incipient assessment method for postconstruction settlement of highway subgrade by using statistical analysis approach with an improved static loading test method, time-extended loading test. The time-extended loading residual settlement Sr(t) and settlement rate Vs(t) are calculated from the field test data. The test procedure and the corresponding experimental validations are presented. Based on the field test data, a probabilistic model is built to bridge the final residual settlement and the actual postconstruction settlements. The proposed time-extended loading test based assessment system has been validated through three operating and well-documented road sections. According to the validation results, the construction quality can be accurately evaluated at an early stage and the corresponding remedial measures can be applied timely.

Analysis of the Bearing Capacity of Red Clay Foundation Considering Stress Level

Accurately evaluated the bearing capacity characteristic value of red clay is of great important to make use of high strength. Based on analyzing current specifications methods to determine the bearing capacity eigenvalue of red clay foundation, it is found that deficiencies are the limitation of application, the disturbance of determining indexes such as water content, liquid limit, plastic limit and compression modulus, and even lack of reflecting effects of the stress level, the shape and failure mode of subgrade. To deal with these shortcomings, a method for determining the bearing capacity of red clay foundation in view of the stress level was proposed. This method adopts tangent modulus that can reflect different depth of stress levels instead of compression modulus to calculate the curve of load and settlement under the size of plate, and utilizes the modified Vesic formula to consider the influence of the shape and failure mode of ground to calculate the ultimate bearing capacity as major parameter of different depth of stress level calculation. The indoor shear strength index can be used to calculate the ultimate bearing capacity if there is no plate load test. According to the characteristic of the settlement and load curve, the intrinsic value of subgrade bearing capacity is achieved using the plate load test method. Verified through an engineering cases, the characteristic value of the bearing capacity obtained using this method is more consistent with that obtained by the plate load test, meanwhile more flexible in the actual application. It also can be used for reference to determine the characteristic value of bearing capacity in other red clay area.

Portable Electric Hoist for Effectiveness of Construction of 3rd Floor Houses

The development of a city can be measured by the amount of development that has been carried out and its suitability for people needs, which is seen by the increase of demand for Building Construction Permits (IMB certificate) because around 70% of regional income is derived from levies in this sector. The population density of a residential area is no longer possible developed by horizontally, along with the increase in the needs of dwellings and businesses to meet the needs of the construction of houses and businesses by building them in 3rd floor houses Lifting equipment type portable electric hoist is a tool which used to move material from the first floor to the next floor during the construction of 3rd floor houses. The transferred material includes; bricks, ceramics, cement, and other building materials. This research conducted to analyze the design of a Lifting Equipment for Material type portable electric hoist to increase the effectiveness of the construction of 3rd floor houses. This study uses a direct load testing method by lifting up to the maximum test load or tipping load. Lifting and moving of test loads is determined at an altitude of 5 meters and 12 meters from the ground floor surface The results of this research indicates that the five stages load carried out by lifting and moving materials test loads by the design of a portable electric hoist were accepted. Lifting and moving load at sixth floor is rejected because condition of tipping. The rejection of the results from this test became a reference to determine the maximum safe working load for operational design of portable electric hoist only 300 kilograms

THE EXPERIENCE DIFFERENT OF PILING TESTING ON PROBLEMATICAL SOIL GROUND OF ASTANA, KAZAKHSTAN

At the present time, in Astana city is going on works by construction public transport system LRT (Light Railway Transport). LRT is an overhead road with two railway lines. The first stage of construction is including construction of overhead road (bridge) with 22,4 km length and 18 stations. The foundation of bridge is the bored piles with cross-section 1.0HL5 m and length 8-КЗ 5 m. In these conditions, very important to control integrity of concrete body of each bored piles. For checking integrity- applying two methods - Low Strain Method and Cross-Hole Sonic Logging. The aim of this paper is to discuss the advantages and disadvantages of each method using the examples of a real application. The article presents loading tests of large diameter and deep boring piles on the construction site in new capital city of the Republic of Kazakhstan. Finally, some recommendations for testmg methods suitable for problematical ground conditions of Kazakhstan are introduced. Traditionally, pile load tests in Kazakhstan are carried out using static loading test methods. Static pile loading test is the most reliable method to obtain the load-settlement relation of piles. Results of static pile tests using the static compression loading test (by ASTM). static loading test (by GOST) and bi-direction static loading test (by ASTM) methods are presented in this paper. Experienced bored piles with length of 31.5 m. diameter 1000 mm. Hereafter the results of underground testmg by the piles with the methods of vertical static tests of SLT. BDSLT and SCLT are presented, which had been made on Expo 2017 projects, buildings of Pavilion m Astana. Kazakhstan.