English：

The Lancang River Grand Bridge is a top-bearing steel box arch bridge with a main span of300 meters. To study its load-bearing capacity under operational conditions and structural performanceunder the most unfavorable working conditions, load tests were conducted on the completed bridge.Control sections were selected based on the bridge’ s most unfavorable stress states, and deflection andstrain measurements were taken at these sections under static loading. Parameters such as naturalfrequency, damping ratio, impact factor, and dynamic response were tested through pulse tests,vehicletraffic tests, and moving load tests. The experimental data was then compared and analyzed againsttheoretical calculations. The results indicate that under static loading, the deflection and strainverification coefficients of the structure across all working conditions, as well as relative residualdeformation and strain, meet the requirements of the specifications. The relative residual strain anddeformation at the control measurement points exhibit significant surplus. During dynamic load tests, theimpact factor ranged between 0.02 and 0.03, the measured natural frequency exceeded the calculatedvalue, and the damping ratio was less than 5%. The bridge’ s working condition falls within the elasticrange, and its actual strength, stiffness, and load-bearing capacity complywith design and relevant coderequirements.