Steel shoring,as an important temporary support component in construction projects,its compression resistance directly determines the safety and stability of the support system.The compression resistance test is to simulate the actual working state of steel shoring under axial pressure,determine its maximum bearing capacity,yield strength and other key indicators,and verify whether it meets the design requirements and construction safety standards.The test needs to follow standardized procedures,and the specific steps are as follows.
The first step is test preparation,which is the basis for ensuring the accuracy of test results.First,select representative steel shoring samples.For Q195 steel shoring,the samples should be consistent with the actual application specifications,including tube diameter,tube thickness,adjustable length and structural design,and there should be no obvious defects such as bending,rust,welding cracks or deformation on the surface of the samples.Generally,3-5 samples are selected for parallel tests to avoid accidental errors affecting the test results.Then,prepare test equipment,mainly including a universal testing machine(with force value accuracy of±0.5%~±1%in line with GB/T 16491 standard),measuring tools such as vernier calipers and micrometers(with accuracy of 0.01mm),and a data recording device.Before the test,the samples need to be processed:the two ends of the shoring are polished to ensure flatness and parallelism(parallelism≤0.02mm),and there are no burrs or oxidation layers,so as to avoid additional bending stress during the loading process affecting the test results.At the same time,measure the key dimensions of the samples,such as the outer diameter,inner diameter and wall thickness of the tube,and the effective length of the shoring,take the average value of multiple measurements,and calculate the original cross-sectional area of the bearing part,which provides a basis for subsequent data calculation.
The second step is equipment debugging and calibration.Start the universal testing machine and preheat it for 30 minutes to ensure the stability of the force sensor and displacement sensor.Then,calibrate the testing machine according to the operating specifications:use standard weights to calibrate the force value,and use standard gauge blocks to calibrate the displacement,so as to ensure that the test accuracy meets the requirements.Adjust the distance between the upper and lower indenters of the testing machine to match the effective length of the steel shoring sample,and adjust the indenters to be perpendicular to the sample end face through the centering device to ensure that the axial pressure is evenly applied to the sample without eccentric loading,which is an important measure to avoid test result deviation.In addition,check the data recording device to ensure that it can accurately record the force-displacement curve and real-time test data during the loading process.
The third step is loading test and data collection,which is the core link of the compression resistance test.Place the processed steel shoring sample stably on the lower indenter of the testing machine,and ensure that the center of the sample is aligned with the center of the indenter to avoid local stress concentration.According to the material properties of the steel shoring(such as Q195 steel with a yield strength of≥195 MPa)and relevant test standards(such as GB/T 7314-2022,ASTM E9-19),set the loading rate:for Q195 steel shoring,the recommended loading rate is 0.005~0.025mm/mm/min(that is,the deformation per minute is 0.5%~2.5%of the sample height),and the loading rate should not be too fast or too slow—too fast will lead to dynamic effects and high measured strength,while too slow will prolong the test time and affect efficiency.Start the loading program,and the testing machine will apply axial pressure to the sample at a uniform speed.During the loading process,closely observe the deformation of the sample,such as whether there is bending,bulging or welding seam cracking,and record the real-time force and displacement data through the data recording device,so as to form a complete force-displacement curve.
The loading process needs to be carried out until the sample reaches the failure state.For Q195 steel shoring with good plasticity,it will not break suddenly,but will continue to undergo plastic deformation.At this time,the loading can be stopped when the sample height is compressed to 50%of the original height,or the test can be terminated according to the specified plastic deformation(such asσ₀.2,that is,the stress corresponding to 0.2%plastic deformation)as required by the standard;for steel shoring with poor plasticity or structural defects,the loading can be stopped when obvious fracture,severe deformation or loss of bearing capacity occurs,and the maximum pressure at the time of failure is recorded.During the test,it is necessary to record the yield point(the pressure when the sample starts to produce plastic deformation)and the maximum bearing pressure in detail,which are the key indicators to evaluate the compression resistance of steel shoring.
The fourth step is data processing and result evaluation.First,calculate the key mechanical indicators according to the test data and the original cross-sectional area of the sample:the compressive strength(σₙ)is equal to the maximum pressure(Fₘₐₓ)at failure divided by the original cross-sectional area(A₀),and the unit is MPa(megapascal).Then,analyze the force-displacement curve to determine the elastic stage,plastic stage and failure characteristics of the steel shoring,such as whether there is a obvious yield platform,and the form of deformation and failure.Compare the calculated compressive strength,yield strength and maximum bearing capacity with the design requirements and relevant standards(such as the mechanical properties requirements of Q195 steel)to evaluate whether the compression resistance of the steel shoring meets the application requirements.If the test results of the parallel samples are quite different(the error exceeds 5%),the test should be re-conducted to check whether there are problems in the sample selection or test operation.
It should be noted that the compression resistance test of steel shoring must follow relevant standards,including Chinese standard GB/T 7314-2022《Metal Materials-Room Temperature Compression Test Method》,international standard ISO 604-2003,American standard ASTM E9-19 and European standard EN 10002-4:1993,so as to ensure the authority and comparability of the test results.In addition,the test environment should be kept at room temperature(23±5℃),and factors such as humidity and vibration should be avoided affecting the test results.For hydraulic steel shoring,additional tests should be carried out according to relevant standards(such as the withdrawn Australian standard AS 5047-2005)to verify the compression resistance of hydraulic components and joint connections.After the test,sort out the test data,and issue a formal test report,which should include sample information,equipment model,test standard,loading rate,original size,maximum pressure,compressive strength,failure form and force-displacement curve,so as to provide a reliable basis for the application and quality control of steel shoring.
References
GB/T 7714 Format
[1]Anonymous.Steel Shoring Compression Resistance Test Procedure[EB/OL].(n.d.).
[2]Anonymous.GB/T 7314-2022 Metal Materials-Room Temperature Compression Test Method[EB/OL].(n.d.).
[3]Anonymous.Q195 Steel Shoring Mechanical Performance Test Guide[EB/OL].(n.d.).
MLA Format
Anonymous."Steel Shoring Compression Resistance Test Procedure."n.d.
Anonymous."GB/T 7314-2022 Metal Materials-Room Temperature Compression Test Method."n.d.
Anonymous."Q195 Steel Shoring Mechanical Performance Test Guide."n.d.
APA Format
Anonymous.(n.d.).Steel shoring compression resistance test procedure.
Anonymous.(n.d.).GB/T 7314-2022 Metal materials-Room temperature compression test method.
Anonymous.(n.d.).Q195 steel shoring mechanical performance test guide.