Steel structure bearing capacity testing

1. Purpose of testing

• safety assessmentVerify whether the structure meets the design load requirements (such as wind load, snow load, earthquake action).

• fault diagnosisCheck the impact of defects such as rust, deformation, and cracks on the bearing capacity.

• reinforcement and retrofittingProvide data support for expansion and change of use (such as converting factory buildings into commercial ones).

• Accident appraisalAnalyze the causes of accidents such as collapse and deformation.

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2. Testing content and methods

(1) Material performance testing

• Strength and toughness：

• Sampling testCut steel samples for tensile testing (to obtain yield strength, tensile strength, and elongation).

• Surface hardness methodIndirectly calculate the strength using a Leeb hardness tester (such as GB/T 17394.1-2014).

• chemical compositionSpectral analysis (detecting whether elements such as carbon, sulfur, phosphorus, etc. comply with the original design grade).

(2) Geometric dimensions and defects

• cross-sectional dimensionsUltrasonic thickness gauge (residual thickness after corrosion), laser scanning (3D modeling).

• Weld quality：

• Non-destructive testingUltrasonic (UT), radiographic (RT), magnetic particle (MT) testing (GB/T 11345-2013).

• Visual inspectionDefects such as cracks, undercutting, and incomplete welding (rated according to JGJ 81-2002).

(3) Connection node detection

• bolted connectionCheck the pre tightening force with a torque wrench and observe if the bolts are loose or broken.

• Welding nodesSame as weld seam inspection, focus on inspecting stress concentration areas (such as beam column nodes).

(4) Deformation and stability

• Overall deformationTotal station measurement of deflection and tilt (compared to the allowable deviation in GB 50205-2020).

• 局部屈曲Observe the wavy deformation of compression members (such as H-beam flanges).

(5) Load test

• static load testApply loads in stages (such as sandbags, counterweights), monitor strain and deformation.

• dynamic load testSimulate vibration (such as sports car testing) and analyze dynamic response.

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3. Load bearing capacity verification process

1. data collectionIntegrate material strength, cross-sectional dimensions, and defect data obtained from testing.

2. Model establishmentBuild finite element models using software such as SAP2000 and ANSYS.

3. parameter adjustmentAdjust model parameters based on measured defects such as rust and residual stress.

4. Verification analysis：

• Limit state methodVerify strength and stability (GB 50017-2017 Steel Structure Design Standard).

• Reliability assessmentConsider load variation and material degradation (such as GB 50153-2008).

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4. Common problems and solutions

5. Standard specifications

• Testing Standard：

• GB/T 50344-2019 Technical Standard for Building Structure Inspection.

• JGJ/T 152-2019 Technical Standard for On site Inspection of Steel Structures.

• design standards：

• GB 50017-2017 Steel Structure Design Standard.

• GB 51008-2016 "Testing and Identification Standards for Tall and Complex Steel Structures.

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Example report conclusion：

The measured yield strength of a steel beam in a certain factory building is 235 MPa (lower than the original design Q345), and the mid span deflection reaches L/250 (exceeding the limit). It is recommended to use carbon fiber cloth reinforcement or add pillars. '

If a testing plan is needed for specific project types (such as grid structures, steel towers) or special environments (high temperature, corrosion), the requirements can be further refined!