Inspection VietSum introduce to customers the process of construction inspection – Quality control of works – Testing of bolt pulling force – tensile load testing of bolt/threaded connection strength at VietSum.
Works: REHABILITATION 110KV ELECTRICAL SUBSTATION – DISTRICT 8
Items: ELECTRICAL CONTROL CENTER BUILDING
Object Test: Bulong M20x250-8.8 (3 test location)
Location: WARD 2, DISTRICT 8, HO CHI MINH CITY
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The 110KV Substation Project has a construction scale of 8.5m x 32.82m; total height 14.7m compared to the roadbed; number of floors with 3 floors and 1 concrete roof; The work has a foundation structure and foundation wall bracing with reinforced concrete poured in the whole block; frame structure of columns, beams and floors made of reinforced concrete poured in place;
At the time of construction inspection – checking bolt/threaded force pulling force, the work is under construction to reinforce the structure during the drilling phase and insert threaded rods into concrete columns to connect reinforced steel beams.
Photo: Construction inspection – tensile load test connection strength
At the time of construction inspection: The position of the bolt to be towed for the strength test is the M20x25 bolt with a durable grade of 8.8, drilled and anchored with high-strength chemicals to the existing 300×600 concrete column, based on the approved structural reinforcement construction design.
Working capacity of a bolt (C20/25): is the tensile strength and stable working shear capacity of a bolt according to the requirements of the approved structural design, not to mention the influencing factors such as bolt distance, edge distance, actual concrete grade…. .
VietSum-accredited construction standards apply:
– Vietnam standard TCVN 1916:1995 on Bolts, screws, studs and nuts – Technical requirements
– National standard TCVN 9490:2012 (ASTM C900 – 06) on Concrete – Determination of tensile strength
Relevant current regulations.
Process of construction inspection – tensile load testing link strength at VietSum:
Step 1: Preparation for load test: Pre-drilling and transplanting the test specimen (at least 3 samples), the threaded rod sample is selected correctly according to the approved design standard parameters, and the quality of the threaded rod is checked (according to TCVN 1916:1995), buried depth of threaded rods and reaching chemical setting time in accordance with specified standards and manufacturer’s instructions (BS 8539: 2012 standard).
Step 2: Preparation of equipment for pulling test loads: Hydraulic jacks with gauges showing needle pressure, test pump cylinders, wedge boxes inserted into internal threaded pipes for different diameters of reinforcement and threaded rod for testing.
Step 3: Slowly load the test piece until the design strength of the drilled steel specimen is reached, hold for about 2 – 5 minutes until the clock hands come to a complete standstill..
Step 4: Note the value shown on the meter. Record the obtained value in the test report, repeat the above test on the remaining test specimens.
Step 5: Make test report: After completing the test of samples, the data must be signed by the witnessing parties. and evaluate the bearing capacity of the bolt connection strength as satisfactory or unsatisfactory compared with the specified strength of the original design.
Pictures at the site of tensile load testing for link strength by VietSum testing:
Photo: Construction inspection – Drilling before the test specimen M20x25 bolt with thread strength of 8.8
Photo: The device that performs the test is a hydraulic jack with the correct number of calibration stamps for the measuring device
Photo: Analog clock test measuring intensity index link
Photo: Carry out the test, install the wedge box into the threaded rod in accordance with the diameter of the chamber
Photo: Slowly load the test specimen until the design strength is reached
Photo: Note the value shown on the meter
Photo: Continue towing bond strength test loads at other locations as required
When you have doubts about the quality of construction works, or when you need to verify the quality of the work, please contact Vietsum Construction Consultancy and Quality Control Joint Stock Company (VCQC).
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Hotline: 090 959 8771 – Mr Nam
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