Bearing Capacity Tests Research Articles

Mechanical Testing of Connections Blind Bolted to the Thick Glass-Fiber-Reinforced Polymer Spar Cap of a Decommissioned GE37 Wind Turbine Blade

Millions of tons of glass-fiber-reinforced polymer (GFRP) composite wind turbine blades are expected to age out of service over the next 30 years. Research is being conducted on repurposing these structures as new civil infrastructure products. The GFRP material in these decommissioned wind blades has been shown to retain significant strength and stiffness for second-life applications. However, for repurposing as new products, they will need to be connected to other structural members. The connections employed for this need to be designed, evaluated, and tested prior to their use. Here, we present the results of detailed testing of bolted connections for load-carrying appurtenances that will carry the phases and shield wires (e.g., insulators, crossarms, davits, guy wires, posts) to the spar cap of an 11-year-old 1.5 MW GE37 wind blade, intended for use as a repurposed transmission pole (i.e., a BladePole). Details of ASTM-type pull-out and bearing capacity tests using different types of blind bolts, and tests of a full-scale steel bracket connection called a “universal connector,” are reported. The effects of the different blind bolts, pin diameters, and loading directions relative to the composite laminate structure (longitudinal or transverse) for both the coupon- and full-scale connector bracket tests are described. The ability to design and construct robust connections for repurposed wind blade structures was demonstrated.

The influence of internode geometry on the bearing capacity of parallel chord wood trusses

The influence of two factors, web angle and internode spacing, on the bearing capacity of three different configurations of trusses was investigated. The constitutive model of the bearing capacity of trusses was established which are jointly controlled by web angle and internode spacing. With bearing capacity and stability as calculation indexes, the critical web angle and internode spacing values for three different configurations of trusses were obtained quantitatively, the truss structure was designed by combining web angle and internode spacing, the mid-span displacement was further calculated as a theoretical basis for finite element simulation. A bearing capacity test on truss specimens with Spruce-Pine-Fir (SPF) as the base material was conducted using the obtained results. The relationship between the load displacement of the different geometric configurations of trusses and the main failure modes was determined accordingly. Finally, the constitutive model of bearing capacity was established which is jointly controlled by web angle and internode spacing. It was found that the stability of the bearing capacity of the A-type truss (Warren type with vertical bar) increases with an increase in the web angle, but is relatively unaffected by the web angle compared to other truss types. The bearing capacity of the B-type(Warren type) truss increases as the web angle increases and is markedly affected by the web angle. The bearing capacity of the C-type(Pa type) truss decreases as the web angle increases, but this configuration is less affected by the web angle than the B-type. The influence of internode spacing on the load-carrying capacity of the truss weakens with an increase in the web angle, as well. The constitutive model, which was obtained by theoretical calculation and ABAQUS finite element simulation, is valid within the elastic deformation range but is not applicable beyond the elastic deformation range.

Analisis Stabilisasi Tanah Dasar dengan Cerucuk Bambu dan Geotekstil

The road plays an essential role as a driving force for development growth in Sukabumi. The access section is an organic clay type with low bearing capacity, so it needs subgrade stabilization. The DCP test obtained a value of 0.76%. The carrying capacity value is in a poor classification. Therefore, it is necessary to strengthen the soil layer using bamboo culms and geotextiles. After that, it is required to do a field CBR. After supporting bamboo culms, the carrying capacity value is 5.63%. This value meets the CBR requirements in medium classification. Thus, it is necessary to add a pavement layer with geotextile. This bearing capacity test obtained a value of 20.59% and is in excellent classification.

Study on the Safety Evaluation Method of Life-Saving Passage in Building Ruins under the Action of Aftershock

It is essential to evaluate the safety of the life-saving passage in building ruins and to ensure the “double safety” of rescuers and trapped people during the earthquake rescue; however, there are few studies on the safety evaluation method of life-saving passage. In this paper, the vertical displacement of wood shoring is proposed as an evaluation indicator of the saving-life passage considering the characteristics of building ruins and the size of the living space of the trapped. Taking life-saving passage of the pancake-type building ruins as research object, the evaluation of the safety of the life-saving passage was investigated under the action of aftershock. The vertical bearing capacity test of wood shoring is performed in order to obtain the evaluation indicator of saving-life passage. The restart function of ANSYS/LS-DYNA program is used to re-edit the numerical model of the building ruins to construct the life-saving passage, then, the safety evaluation of life-saving passage of the pancake-type building ruins is investigated under the action of aftershock. The results show that the constructed life-saving passage passed the safety evaluation under the actions of different aftershocks. The possibility of the secondary collapse of the life-saving passage increases exponentially with the increase of rescue time within “72-hour gold rescue,” and the growth is slow after 72 hours when the magnitude of the main earthquake reaches above 7.4; the safety factor K should be increased appropriately if wood shoring is used to construct a life-saving passage when the main earthquake’s magnitude is greater than or equal to 7.5. The safety evaluation method of life-saving passage can provide effective reference for earthquake rescue.

Mechanical properties of axially and eccentrically loaded CFRP–coral concrete columns

Bearing capacity tests were carried out on axially and eccentrically loaded coral concrete short columns reinforced with carbon-fibre-reinforced polymer (CFRP) bars. Parameters such as the ultimate bearing capacities and the stress in the CFRP bars and surface concrete were measured and analysed. All the columns failed due to the crushing of concrete in the compression zone. An increase in eccentricity not only decreased the ultimate bearing capacity, but also resulted in the shear fracture of CFRP longitudinal bars in the compression zone. In general, the stress of the longitudinal CFRP reinforcements in all specimens was quite low. The maximum stress of the CFRP bars in the columns was 105.78 MPa, just 23.5% of the ultimate compressive strength of the CFRP reinforcement. The superior bond between the CFRP bars and coral concrete conformed to the deformation coordination. A calculation method for the bearing capacity of CFRP-reinforced coral concrete short columns was developed and the calculated results were found to agree well with the test results.

Structure Bearing Capacity Testing and Evaluation of Existing Bridges

The bearing capacity testing and evaluation of the existing bridge engineering structure is not only the key to clarify its structural quality and safety performance, but it also can lay a solid foundation for subsequent repairs and maintenance work. To ensure the bearing capacity, durability and reliability of existing bridges, this paper analyzes the importance and methods of testing and evaluation of structural bearing capacity of a bridge. This analysis aims to provide scientific reference for the quality assessment and subsequent repair and maintenance of existing bridge engineering structures.

Research on seismic performance of honeycomb plate cylindrical reticulated shell structure

In previous research, an aluminum alloy honeycomb plate cylindrical reticulated shell structure was designed. The bearing capacity test and numerical analysis show that the numerical analysis model of honeycomb plate cylindrical reticulated shell structure is reliable. In this paper, the seismic performance of the honeycomb plate cylindrical reticulated shell structure was investigated by modal analysis and time-procedure analysis. The results show that the low-order vibration modes of the cylindrical reticulated shell structure are generally dominated by lateral translational, plane torsional or vertical vibration. The natural frequency of cylindrical reticulated shell structure with bottom plate is greater than that of cylindrical reticulated shell structure without bottom plate, which has more reasonable mass, stiffness distribution. The cylindrical reticulated shell structure with bottom plate has better seismic performance, and its deformation under rare earthquake meets the specification requirements.

Experimental study of local – Distortional interaction of press-braked stainless steel lipped channel beams

Stainless steel lipped channel beams are prone to complex buckling modes due to the large width-thickness ratio. An in-depth experimental study of local – distortional interaction of press-braked stainless steel lipped channel beams was conducted. The chemical composition was proved to meet the requirements of European and Chinese standards. A tensile test of four coupons extracted from the press-braked lipped channel beams was carried out to investigate the material properties. A total of 10 specimens composed of 20 press-braked stainless steel lipped channel beams were investigated in the bearing capacity test. The relationship of the vertical displacement of mid-span, vertical displacement of loading points, support rotation, flange deformation and web deformation with the load was obtained, as well as the bearing capacity of each specimen. According to the measured displacement and strain, the development and failure mechanism of local – distortional interaction of stainless steel lipped channel beams were revealed. All test specimens were subjected to local buckling first, then distortional buckling, and finally interaction buckling. Each specimen had a certain post buckling strength. Near the failure load, each specimen experienced a long loading process and showed good ductility. The test results were utilized to assess the existing design methods which were all based on Direct Strength Method for the guidance of engineers. The existing design methods for local – distortional interaction underestimated the bearing capacity of press-braked stainless steel lipped channel beams. The existing design methods for local buckling or distortional buckling of stainless steel beams overestimated the bearing capacity of local – distortional interaction.

Retracted: Test of Ultimate Bearing Capacity of Building Concrete Structures in Earthquake Area Based on Virtual Reality

Retracted: Test of Ultimate Bearing Capacity of Building Concrete Structures in Earthquake Area Based on Virtual Reality

Underground testing of load bearing capacity of rock bolting as part of the verification of its proper selection

Underground testing of load bearing capacity of rock bolting as part of the verification of its proper selection

Experimental study on bearing capacity of corroded angle steel members of in-service transmission towers

The tower is the load-bearing structure of the overhead transmission line. Due to the complex operating environment and other factors, the transmission tower is prone to corrosion, which weakens the bearing capacity of the tower and affects the safe operation of the power grid. Through the investigation of the corrosion situation of the transmission towers in service, the angle steel members were removed from the in-service transmission towers, and the axial compression bearing capacity test was carried out. As the corrosion rate increases, the bearing capacity of components shows a decreasing trend, and due to the existence of corrosion, and at the same corrosion rate, due to the location of corrosion, The corrosion depth and corrosion area are different, and the axial compression bearing capacity of the components fluctuates greatly.

A case study on the bearing characteristics of a bottom uplift pile in a layered foundation

The bottom uplift pile, which has been applied in practical projects, has the following advantages: the pile body is not easy to crack, good bearing characteristics, and small displacement of the pile top. Based on the bearing capacity test of foundation piles in the third stage expansion project of Lanzhou Zhongchuan International Airport, the upper part pile of the self-balancing test method was used to simulate the bottom uplift pile, and the anchor piles in the anchor pile method were regarded as normal uplift piles. The bearing characteristics of the bottom uplift pile in a layered foundation were studied by comparing these two kinds of piles. The results show that under the same displacement of the pile top, the ultimate uplift bearing capacity of the bottom uplift pile can be more than twice that of the normal uplift pile because of the fully exerted frictional resistance of the soil at the bottom of the pile, the Poisson effect of the pile body and the avoidance of the influence of pile body deformation on the pile top displacement. The maximum axial force of the bottom uplift pile appears at the bottom of the pile and gradually decreases from the bottom to the top, which is opposite to that of the normal uplift pile. The properties and thickness of the soil layers around the pile have a great influence on the distribution curves of the frictional resistance along the pile length of the two kinds of uplift piles. With changing soil layer conditions, the distribution curve may be a "parabola", a "straight line" or a "double line". The soil property plays a decisive role in the frictional resistance, which may cause softening. The influence of the pile diameter on the ultimate uplift bearing capacity is greater than that of the pile length, while the elastic modulus of the pile has little influence.

Design of a Visual Training System for Software Engineering Education Based on Knowledge Graphs

With the increase of the content and difficulty of software engineering education courses, software engineering education visual training system came into being, but the technology is not mature at present, and the representation learning algorithm part of the visual training system needs to be optimized. In order to solve this problem, the research proposes to optimize the take model by using the trans representation algorithm, and embed the optimized knowledge map into the new software engineering education visual training system. The performance of TEKEE model is verified by comparing TEKEE model with Trans E model, Trans D model and TEKED model. The experimental results show that the MR value of the optimized TEKEE model is 62, Hits@10 The value is 0.92, which is better than the other three representation learning models. In terms of the bearing capacity test of the visual training system, the response time of the business operation of the research and design training system is 1.22 seconds, and the CPU occupancy of the application server is 12.5%, all of which are normal. The experimental results show that the performance of the optimized TEKEE model has indeed been greatly improved, and the visual training system composed of the optimized knowledge map has a very good carrying capacity, which can provide a new idea for the software engineering education and training system.

S600E high-strength stainless steel welded section columns: Bearing capacity test and design method

S600E high-strength stainless steel has a yield strength greater than 600 MPa and a cost lower than that of commonly used austenitic stainless steel; thus, it has broad applications in construction. In this study, the behaviour of S600E high-strength stainless steel columns was investigated. To that end, tests on six welded Box-section specimens and 12 I-section specimens were performed. The material properties, capacities, and failure modes of the specimens were evaluated. Thereafter, the capacities of the specimens were compared with the values predicted using the current European, American, and Chinese design codes. The results indicated that the values predicted by the American code were generally unsafe, while the predictions of the European and Chinese design codes were conservative, particularly for I-section columns buckling about the minor axis. Subsequently, finite element models were built and verified using the test results. Based on the finite element analysis results, the design formulae for capacities of S600E high-strength stainless steel columns subjected to the global and local buckling were modified and combined to formulate a complete design method for the columns. Finally, the values predicted by the proposed design method were compared with the test data, which verified the accuracy of the proposed design method.

Local – distortional interaction buckling of stainless steel lipped C-section beams

Based on a bearing capacity test of 10 specimens composed of 20 stainless steel lipped C-section components, a refined finite element model was established and verified to investigate the failure mode and bearing capacity. 267 numerous parametric analyses were carried out to investigate the effects of the distribution and amplitude of initial geometric imperfections, strength improvement of corner and buckling slenderness ratio on the buckling modes and bearing capacity of stainless steel beams. The effects of both distribution and amplitude of initial geometric imperfections on the bearing capacity were significant. However, the effect of amplitude of initial geometric imperfections on the buckling modes was small. When the ratio of cross-sectional area of corner to the whole cross-sectional area was smaller than 5%, the increase of strength improvement of corner to the bearing capacity was within 5%. When the ratio was larger than 5%, the increase was more significant. The existing methods for calculating the bearing capacity of local – distortional interaction buckling of carbon steel and high-strength steel lipped C-section beams underestimate that of stainless steel lipped C-section beams. Therefore, two design methods for local – distortional interaction buckling of stainless steel lipped C-section beams based on Direct Strength Method were proposed for the first time. A reliability analysis of the proposed methods was conducted to verify the reliability for engineering application.

Design and bearing capacity test of prefabricated high-strength thin concrete segments for reinforcing underground box culverts

The application of prefabrication technology in underground engineering has been mostly concentrated in subway tunnels and subway stations. Research on the prefabrication technology of underground box culverts is relatively recent. There is almost no research on the improvement in structural performance of aging box culverts using prefabricated assembly technology. Traditional trenchless rehabilitation technology was developed from the rehabilitation of round pipes and was applied to underground square pipes, such as box culverts, after certain improvements. These methods produce a limited increase in the structural bearing capacity of aging underground box culverts and are time-consuming to construct. In this regard, this paper puts forward the idea of reinforcement with and a design method using prefabricated assembly technology to reinforce the interior of a box culvert with high-strength thin-walled concrete segments. A case study was analyzed and a construction simulation was verified. A full-scale prefabricated high-strength concrete segment was subsequently subjected to horizontal and vertical equal-proportion loading static bearing capacity tests. The results showed that the designed and manufactured prefabricated high-strength concrete segment can be independent of the original structural bearing capacity and without its beneficial constraints to meet the design requirements of bearing capacity. It should be noted that in this experiment, the prefabricated segments eventually suffered shear failure at the splice joints, and attention should be given to strengthening the local structure of the splice joints. The reinforcement method proposed in this paper is also applicable to other similar structures with box-shaped internal space sections.

Research on bearing capacity of honeycomb plate box-type hollow roof structure

• A new type of honeycomb plate box-type hollow roof structure is prepared with good ductility. • The validity of the numerical analysis model was verified by comparing the results of experiment with the results of the coupling model. • Influential factors on the bearing capacity of honeycomb plate box-type hollow roof structure obtained by parametric analysis. In this paper, a new type of honeycomb plate box-type hollow roof structure was prepared. The failure modes and mechanical properties of the box-type hollow roof structure were analyzed by bearing capacity test and numerical simulation. The validity of the numerical analysis model was verified by comparing the results of experiment with the results of the coupling model. The influence of specification of honeycomb plate, height of the side plate, rise-span ratio of the structure, configuration of box-type hollow roof structure, and initial geometric defect on the bearing capacity of the honeycomb plate box-type hollow roof structure were analyzed. The results show that the failure mode of the specimen is tensile failure of the surface plane of the honeycomb plate with strengthened frame and buckling instability of the plate near the joint. The results of coupling model are in good agreement with the results of experiment. The stiffness of honeycomb plate box-type hollow roof structure can be improved by the thickness of plate and the height of core layer of honeycomb plate. The ultimate bearing capacity of the honeycomb plate box-type hollow roof structure increases with the increase of the height and rise-span ratio. The bottom plate of box-type hollow roof structure can make the force transmission path of the structure more reasonable and effectively reduce the phenomenon of stress concentration. Compared with the structure without initial geometric defect, the stable bearing capacity of the structure is reduced by 18.6 % and the ultimate bearing capacity is reduced by 28 % when the initial geometric defect of 80 mm is applied to the structure.

Research on the Analytical Conversion Method of Q-s Curves for Self-Balanced Test Piles in Layered Soils

An analytical conversion method was developed for the self-balanced test results of monopile bearing capacity in layered soils to realize the better applicability of the self-balanced test theory for the bearing capacity test of foundation piles. To the additional settlement of the lower pile bottom brought on by the negative friction of the upper pile soil during the loading process in layered soils, the interaction effect between the upper piles and lower piles is first taken into account. To accurately convert the results of the self-balanced test pile into the traditional static load test curve form and solve the ultimate bearing capacity, the displacements and internal forces at micro-segment piles in each layer of soil were obtained using the finite difference method. Then, for verification, conventional static test piles and indoor model tests were conducted in a multi-layered ground foundation. The outcome demonstrates that the simplified conversion method’s bearing capacity of the test pile is greater than that of the traditional static pressure test, the analytical conversion method’s Q-s curve is relatively similar to the results of the conventional static load test, and the accuracy of the analytical conversion results is increased by about 9.3 percent. At the same time, the analytical conversion method was applied to the self-balanced test project of bored cast-in-place piles in Wutong Garden, Laibin, Guangxi, China, and the accurate bearing capacity and internal force deformation characteristics were obtained. The accuracy of the calculation result is improved by 12% compared with that of the simple conversion calculation result. Therefore, it can be widely promoted and applied in self-balanced pile bearing capacity test projects.

Experimental investigation into the close-in blast performance of RC columns with axial loading

The high cost and long consuming time of field blast test result in that the experimental study on the blast performance of reinforced concrete (RC) column subjected to blast loads and axial loading is limited in the previous study which focuses on the numerical investigation. As the critical reference which is utilized to verify the accuracy of the numerical simulation, it is necessary to carry out the experimental study for the RC column subjected to close-in blast loads and axial loadings. In this study, the lateral displacement and failure characteristic of RC column with initial axial loading subjected to close-in blast loads are analyzed based on the field blast test. The influence of charge mass, detonation distance and axial load on the lateral displacement and failure mode of RC column subjected to close-in blast loads is discussed. The experimental result shows that the close-in blast loads can induce serious local damage, which is characterized as the concrete crushing at the front blast surface and concrete spallation at the rear blast surface. The decrease of scaled distance has a negative influence on the close-in blast performance of RC column, while the increase of axial compression ratio has different influences on the close-in blast performance of RC column under different scaled distances. In order to assess the damage degree of RC column subjected to close-in blast loads, the residual bearing capacity test of blast-damaged RC column is carried out. The decrease of scaled distance makes the blast damage degree of RC column transform from low damage to medium damage under the certain combination of scaled distance and axial loads. The increase of axial compression ratio makes the blast damage degree of RC column transform from low damage to medium damage under the certain combination of scaled distance and axial loads.

Experimental and numerical study on the mechanical properties of honeycomb plate box-type hollow roof structure

In this paper, a new honeycomb plate box-type hollow roof structure is prepared. The failure mode and mechanical properties of the box-type hollow roof structure were analyzed by bearing capacity test and numerical analysis. The validity of the numerical analysis model is verified by comparing the results of bearing capacity test with the results of the complete coordinated model and the coupled model analysis. The results show that the failure mode of the specimen is tensile failure of the surface plate of the honeycomb plate with strengthened frame and buckling instability of the plate near the joint. The box-type hollow roof structure has good ductility. The results of static analysis and nonlinear buckling analysis of the honeycomb plate box-type hollow roof structure are carried out by coupling model are more consistent with the results of bearing capacity test.