How to do on-site load test for dock bollards

How to do on-site load test for dock bollards

Implementation Standards: JT/T 391-2016 "Port Mooring Bollards", JTS 169-2017 "Technical Specifications for Dock Ancillary Facilities", JTS 257 Quality Inspection Standards for Water Transport Engineering

Test Objectives: To verify the overall pull-out/horizontal tensile bearing capacity of the mooring bollard body, anchor bolts, and concrete foundation. The tests are divided into two categories: factory bench tests and on-site acceptance tests after installation at the dock. On-site tests mainly use the static load method with hydraulic jacks.

I. Preparations before the test

1. Core instruments and equipment (all must have valid calibration certificates)

1. Loading System: Large-tonnage hydraulic jacks + electric oil pump (rated loading force ≥ 1.5 times the bollard design tensile force SWL)

2. Force Measuring Device: Standard force sensors (pressure sensors/force gauges), accuracy within 0.5 grade, real-time digital display

3. Displacement Monitoring: Dial gauges/laser rangefinders (for measuring horizontal and vertical deformation at the bollard top)

4. Tooling and Auxiliary Materials: High-strength steel cables, shackles, guide pulleys, reaction supports (concrete counterweights/embedded anchor beams), limit brackets

5. Safety Protection: Warning barriers, sandbags, walkie-talkies, emergency shut-off valves

2.Operating conditions and loading angle (simulating real mooring)

Ship mooring cables are not purely horizontal and need to be loaded at three typical angles:

1. Horizontal 0° (parallel to the front edge of the dock, most commonly used)

2. Depression angle 15° (the ship is pulled down at low water level)

Elevation angle 15° (high water level pull-up)

If there is no special design, priority will be given to the horizontal 0° main working condition acceptance

3.Load values (mandatory national standard)

• Acceptance test load: 1.25 times the rated working tensile force SWL, held for 30 minutes

• Acceptance criteria: No cracks, no slippage, no permanent plastic deformation; residual deformation after unloading ≤ allowable value

4.On-site foundation and reaction force layout

1. Reaction point: At least 3 meters away from the bollard to be measured, using existing pre-embedded anchorages and heavy concrete counterweights at the wharf. Sharing adjacent bollards for reaction force is strictly prohibited (to avoid collateral damage).

2. Tooling connection: Steel cables are secured to the middle of the bollard neck, with soft padding to prevent damage to the cast steel surface; pulleys ensure the tension direction is completely consistent with the design angle.

3. Measuring point arrangement: One dial indicator on each side of the bollard top measures horizontal offset; the side of the base plate measures base plate slippage; concrete cracking is observed on the side of the foundation.

II Mainstream testing method (on-site preferred hydraulic jack static load method)

Method 1: Static load method using hydraulic jacks (standard method for on-site acceptance at the dock)

Step 1: Preloading to eliminate gaps

Gradually load to 50% SWL, stabilize for 5 minutes, then completely unload; repeat twice to eliminate gaps in steel cables, bolts, and foundation, and reset the initial reading of the displacement gauge to zero.

Step 2: Gradual and uniform loading (impact and sudden loading are strictly prohibited)

Gradient loading: 20%→40%→60%→80%→100%→125% SWL. After each loading stage, stabilize the pressure for 5 minutes and record the following simultaneously: real-time tensile force value, horizontal displacement of the column top, slippage of the base plate, and whether there are cracks or abnormal noises on the surface.

Step 3: Full-load observation (critical acceptance test)

Load to 1.25 times the rated tensile force and maintain pressure continuously for 30 minutes;

Record a set of data every 5 minutes, and conduct a visual inspection throughout the process:

• Check for cracks or peeling in the mooring bollard castings/welds

• Check for elongation or loosening of the anchor bolts

• Check for gaps or slippage between the bollard base plate and the concrete

• Check for radial cracks or spalling in the wharf foundation concrete

Step 4: Staged unloading and measurement of residual deformation

Unload in stages: 125% → 100% → 80% → … → 0, with a 3-minute pause at each stage; After completely unloading, let stand for 15 minutes and read the final residual displacement.

Conformity criteria (JT/T391)

1. No breakage, obvious abnormal noise, or visible cracks throughout the entire loading process;

2. No slippage of the base plate and no plastic elongation of the anchor bolts;

3. Residual deformation after unloading is ≤5% of the total loading deformation and not greater than 3mm;

4. No through cracks or spalling in the concrete foundation.

III  Key points of multi-angle loading operation (simulating high and low water levels)

1. Horizontal 0°: The pulley is at the same height as the column center, with pure horizontal tension, and the foundation is subjected to pure horizontal shear force;

2. 15° Downward Angle: The pulley is below the column center, with the tension band exerting a vertical downward component of the force, testing the pull-out resistance of the base plate and the local bearing capacity of the concrete;

3. 15° Upward Angle: The pulley is above the column center, with the tension band exerting a vertical pull-out force, focusing on testing the tensile strength of the anchor bolts and the resistance of the base plate to uplift.

Only when all three angles pass the test is the overall stress of the mooring bollard considered to meet the standard.

IV Safety Management (High-Risk Testing Red Line)

1. The test area shall be completely enclosed and cordoned off. No personnel are allowed to stand within the cable's stress zone. Two buffer walls shall be erected.

2. The test shall be terminated immediately upon the occurrence of any of the following situations during loading:

•The tensile force cannot be stabilized, or the value continues to drop;

•Cracks or abnormal noises appear in the column/foundation;

• The displacement increases rapidly and continuously (plastic slippage);

• Deformation and bulging occur in the steel cable, shackles, and jacks;

3. The oil pump shall be equipped with a remote pressure relief valve. Personnel shall stand in the 90° safety zone to the side of the tensile force and shall not face directly towards the direction of the cable's stress;

4. The test shall be stopped during strong winds, high or low tides, or surges exceeding 0.3m.

V Required content of test report

1. Project Information: Berth number, bollard model, rated SWL, serial number, anchor bolt specifications;

2. Instrument calibration certificate number, loading angle, loading curve record sheet;

3. Displacement records for each load level, observation records for 30 minutes under full load, residual deformation after unloading;

4. Photos of external defects (comparison before loading, under full load, and after unloading);

5. Test conclusions, signatures of testing personnel and supervisor.

VI Common non-compliance phenomena and causes

1. Excessive residual deformation after unloading: Insufficient anchor bolt strength, missing base plate pad, insufficient foundation concrete strength;

2. Base plate slippage: Insufficient pre-embedded anchor bars, hollow areas in secondary grouting;

3. Column casting cracking: Casting defects, load exceeding design value;

4. Foundation cracking: Unreasonable arrangement of reaction support points, insufficient local bearing capacity.