• Structural Engineering and Mechanics
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• v.39 no.4
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• pp.521-539
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• 2011

Jilin highway concrete bridge is located in the center of Jilin City, which is positioned in the middle part in Jilin Province in the east north of China. This bridge crosses the Songhua River and connects the north and the south of Jilin City. The main purpose of damages inspection of the bridge components is to ensure the safety of a bridge and to identify any maintenance, repair, or strengthening which that need to be carried out. The damages that occur in reinforced concrete bridges include different types of cracks, scalling and spalling of concrete, corrosion of steel reinforcement, deformation, excessive deflection, and stain. The main objectives of this study are to inspect the appearance of Jilin highway concrete bridge and describe all the damages in the bridge structural members, and to evaluate the structural performance of the bridge structure under dead and live loads. The tests adopted in this study are: (a) the depth of concrete carbonation test, (b) compressive strength of concrete test, (c) corrosion of steel test, (d) static load test, and (e) dynamic load test. According to the damages inspection of the bridge structure appearance, most components of the bridge are in good conditions with the exception arch waves, spandrel arch, deck pavement of new arch bridge, and corbel of simply supported bridge which suffer from serious damages. Load tests results show that the deflection, strain, and cracks development satisfy the requirements of the standards.

• Geomechanics and Engineering
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• v.7 no.5
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• pp.477-493
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• 2014

This study examines the behaviour of single micropiles subjected to axial tension or compression load in collapsible loess under in-situ moisture content and saturated condition. Five tension loading tests and five compression loading tests on single micropiles were carried out at a typical loess site of the Loess Plateau in Northwest China. A series of laboratory tests, including grain size distribution, specific gravity, moisture content, Atterberg limits, density, granular components, shear strength, and collapse index, were carried out during the micropile loading tests to determine the values of soil parameters. The loess at the test site poses a severe collapse risk upon wetting. The tension or compression load-displacement curves of the micropiles in loess, under in-situ moisture content or saturated condition, can generally be simplified into three distinct regions: an initial linear, a curvilinear transition, and a final linear region, and the bearing capacity or failure load can be interpreted by the L1-L2 method as done in other studies. Micropiles in loess should be considered as frictional pile foundations though the tip resistances are about 10%-15% of the applied loads. Both the tension and compression capacities increase linearly with the ratio of the pile length to the shaft diameter, L/d. For micropiles in loess under in-situ moisture content, the interpreted failure loads or capacities under tension are 66%-87% of those under compression. However, the prewetting of the loess can lead to the reductions of 50% in the tensile bearing capacity and 70% in the compressive bearing capacity.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.211-222
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• 2019

This study evaluates the yield load and allowable bearing capacity of ground in compressive loading tests to confirm the effect of CPR foundation reinforcement. The average compressive strength of the injection materials was higher than the planned compressive strength. Standard penetration tests for each stratum showed that foundation reinforcement improved the average N values, thereby increasing the bearing capacity of the ground. Compressive loading tests on two CPR piles revealed that the total and net settlement due to the maximum load exceed that permissible for the CPR pile diameter. The yield load and allowable bearing capacity calculated by the settlement criterion and the load-settlement curves varied greatly with the method applied. Therefore, it seems to be necessary to determine the optimum value through comprehensive analysis after applying various yield load calculation methods.

• Steel and Composite Structures
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• v.13 no.6
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• pp.571-586
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• 2012

The paper addresses some key issues related to the design of composite slabs with cold-formed profiled steel sheets. An experimental programme is first presented, involving six composite slab specimens tested with a view to evaluating Eurocode 4 (EC4) provisions on testing of composite slabs. In four specimens, the EC4-prescribed 5000 load cycles were applied using different load ranges resulting from alternative interpretations of the reference load $W_t$. Although the rationale of the application of cyclic loading is to induce loss of chemical bond between the concrete plate and the steel sheet, no such loss was noted in the tests for either interpretation of the range of load cycles. Using the recorded response of the specimens the values of factors m and k (related to interface shear transfer in the composite slab) were determined for the specific steel sheet used in the tests, on the basis of three alternative interpretations of the related EC4 provisions. The test results confirmed the need for a more unambiguous description of the m-k test and its interpretation in a future edition of the Code, as well as for an increase in the load amplitude range to be used in the cyclic loading tests, to make sure that the intended loss of bond between the concrete slab and the steel sheet is actually reached. The study also included the development of a special-purpose software that facilitates design of composite slabs; a parametric investigation of the importance of m-k values in slab design is presented in the last part of the paper.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.635-648
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• 2020

Performance improvement of helical piles in static load tests using hexagon joints that do not require welding or bolting was investigated. Two sites were selected for pile field tests to evaluate their bearing capacity. Static and pull-out load tests were undertaken to assess the method for estimating bearing capacity. The field tests indicated that the bearing capacity of the gravity grout pile was ≥600 kN in the static load test, consistent with the AC 358 Code. The non-grout pile had a bearing capacity of ≤600 kN, suggesting that gravity grouting is required. Field pile load-test results were used to establish the bearing capacity equation, based on a small number of helical pile.

• Journal of the Korean Geotechnical Society
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• v.30 no.3
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• pp.5-16
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• 2014

Soil-nailing has two main resistance factors: skin friction between ground and grouting; and tension load of reinforced material. These two factors will affect the load-displacement curve when performing soil-nailing pullout tests. The purpose of this paper is to figure out the shear behavior between ground and soil-nailing focusing on the net load-displacement behavior during soil-nailing pullout tests. Firstly, the net load-displacement curve between ground and grouting is estimated theoretically. Then, in-situ pullout load tests are performed on various ground conditions to obtain the load-displacement curve occuring between ground and grouting. Since the measured shear displacement includes elongation of the reinforced material (steel nails), the net load-displacement curve can be obtained by subtracting the elongation magnitude of steels from the measured displacement. It was found that the measured net load-displacement curve matches reasonably well with the theoretically estimated curve.

• Journal of the Korean Geotechnical Society
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• v.22 no.7
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• pp.23-35
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• 2006

Shear load transfer characteristics of rock-socketed drilled shafts were analyzed. The constant normal stiffness (CNS) direct shear tests were performed to identify the major influencing factors of shaft resistance, i.e., unconfined compressive strength, borehole roughness, normal stiffness, initial confining stress, and material properties. Based on the CNS tests, shear load transfer function of drilled shafts in rocks is proposed using borehole roughness and the geological strength index (GSI), which indicates discontinuity and surface condition of rock mass in Hoek-Brown criterion (1997). The proposed load-transfer function was verified by the load test results of seven rock-socketed drilled test shafts subjected to axial loads. Through comparisons of the results of load tests, it is found that the load-transfer function by the present study is in good agreement with the general trend observed by in situ measurements, and thus represents a significant improvement in the prediction of load transfer of drilled shafts.

• Journal of the Korean Geotechnical Society
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• v.25 no.8
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• pp.77-93
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• 2009

The load distribution and deformation of rock socketed drilled shafts subjected to axial loads were evaluated by a load transfer approach. The emphasis was laid on quantifying the end bearing load transfer characteristics of rock socketed drilled shafts based on 3D Finite Difference (FD) analysis performed under varying rock strength and rock mass conditions. From the results of FD analysis, it was found that the ultimate unit toe resistance ($q_{max}$) was influenced by both rock strength and rock mass conditions, while the initial tangent of end bearing load transfer curve ($G_{ini}$) was only dependent on rock strength. End bearing load transfer function of drilled shafts socketed in rock was proposed based on the FD analysis and the field loading tests which were performed on weathered rock in South Korea. Through the comparison with the results of the field loading tests, it is found that the load transfer curve by the present study is in good agreement with the general trend observed by field loading tests, and thus represents a significant improvement in the prediction of load transfer behavior of drilled shaft.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.5
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• pp.10-21
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• 2006

For analyze of the bearing capacity, skin friction and settlements of pile on axial compressive loading, both Load transfer tests of pile and pile loading test in field have application to commonly before pile installing. A bearing capacity of pile was affected by the characteristics of surrounding ground of pile. Especially, that is very different because of evaluation of settlement due to each soil conditions of ground depths. The ground characteristics using evaluation of bearing capacity of pile through load transfer analysis depends on N values of SPT, and then a bearing capacity of pile installed soft ground and refilled area may be difficult to rational evaluation. An evaluation of bearing capacity on pile applied axial compressive loading was effected by strength of ground installed pile, unconfined compressive strength at pile tip, pile diameter, rough of excavated surface, confining pressure and deformation modules of rock etc and these are commonly including the unreliability due to slime occurred excavation works. Load transfer characteristics considered ground conditions take charge of load transfer of large diameter pile was investigated through case study applied load transfer tests. To these, matrix analytical technique of load transfer using finite differential equation developed and compared with the results of pile load test.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.691-696
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• 1997

In recent years, stengthening of beam by steel plate, carbon fiber sheets, and carbon fiber laminate is spotlighted in order to repair and rehabilitation of R/C structures. In this study, 3 method of rehabilitation technic are analyzed from the tests. Test parameters are the width of cracks, the method of repair and rehabilitation, the magnitude of existing load. Deflection, failure load, strains of reinforcing bar, strains of sheet and plates are measured during tests. The failure mode and ultimate load are analyzed from these measured data. Test result shows that the width of cracks and the magnitude of existing load do not make any difference of ultimate flexural capacity.