Non-destructive anchor bolt pull out load capacity testing system

Patent metadata

Field	Value
Publication number	US-11293845-B2
Application number	US-202117197178-A
Country	US
Kind code	B2
Filing date	Mar 10, 2021
Priority date	Dec 12, 2017
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

A tester for evaluating pullout load capacity and bond quality of anchor bolts embedded in concrete includes a Schmidt hammer for measuring a rebound number and an ultrasonic pulse velocity tester for measuring the transit time of a pulse transmitted through concrete surrounding an anchor bolt. The rebound number and the transit time are combined and matched against a database record which identifies the pullout load capacity and the bond quality. The transit time is matched to thresholds of transit times associated with porosity, internal cracking, air voids, and water pockets located around the embedded anchor bolt. The Schmidt hammer is further modified by the incorporation of a digital level for measuring the vertical and horizontal angles of inclination of the plunger with the concrete surface, a guide tube for supporting the plunger, and by using a convex plunger tip for improved registration with anchor bolt head.

First claim

The invention claimed is:

1. An anchor bolt pull out load capacity testing system, comprising:
a Schmidt hammer including a plunger having a convex distal tip, wherein the Schmidt hammer is configured to impart an impact force on an anchor bolt embedded in concrete in registration with the convex distal tip and to record a rebound distance travelled by an impact mass,
data analysis circuitry configured to determine a rebound number based on the rebound distance travelled by the impact mass;
an ultrasonic pulse velocity tester having a transmitting transducer and a receiving transducer, wherein the transmitting transducer is configured to contact the concrete at a first location surrounding the anchor bolt and the receiving transducer is configured to contact the concrete at a second location surrounding the anchor bolt and spaced from the first location;
circuitry configured to drive the transmitting transducer to send an ultrasonic pulse through the concrete at a first time, the circuitry further configured to receive an electrical signal generated by the receiving transducer based on the ultrasonic pulse at a second time, the circuitry including first processing circuitry configured to determine the transit time of the ultrasonic pulse through the concrete based on the difference between first time and the second time;
a controller in communication with the Schmidt hammer, the data analysis circuitry and the ultrasonic pulse velocity tester, the controller having second processing circuitry configured to correlate a Schmidt hammer rebound number with the ultrasonic pulse transit time within the concrete to determine a pullout load capacity and the bond quality of the embedded anchor bolt;
a digital level connected to the Schmidt hammer and including a magnet and a plurality of Hall effect sensors, wherein the Hall effect sensors generate signals based on the gravitational magnetic field and the magnetic field of the magnet, and
a data analysis module including circuitry configured to receive the Hall effect signals from the digital level, calculate vertical and horizontal angles of inclination of the Schmidt hammer based on the Hall effect signals, and correct the rebound number based on the vertical and horizontal angles of inclination, and display the vertical and horizontal angles of inclination and the corrected rebound number on the display of the Schmidt hammer body.

2. The testing device of claim 1 , wherein the Schmidt hammer body further comprises a guide tube having a distal end configured to contact the concrete surface, the guide tube further configured to support alignment of the plunger with the anchor bolt in order to alleviate slippage of the distal tip on the anchor bolt.

3. The system of claim 1 , wherein the Schmidt hammer has a body having a central axis, a proximal end and a distal end coaxially located with the central axis; the Schmidt hammer further comprising:
the impact mass disposed coaxial with and displaceable along the central axis from the proximal end towards the distal end to impact against the plunger;
a drive mechanism for driving the impact mass along the central axis;
a rebound detector to measure the rebound distance;
a display;
a transmitter; and
a data acquisition module to receive the rebound distance,
wherein the plunger is coaxially located along the axis, the plunger having a proximal end for receiving the impact from the impact mass.

4. The system of claim 3 , wherein the data analysis has circuitry configured to display the rebound number and transmit the rebound number to the controller.

5. The system of claim 4 , wherein the data analysis module including circuitry configured to display the vertical and horizontal angles of inclination and the corrected rebound number on the display of the Schmidt hammer body.

6. A non-destructive testing method for evaluating the pullout load capacity and bond quality for anchor bolts embedded in concrete, comprising:
measuring a rebound number of an anchor bolt embedded in concrete by using a Schmidt hammer;
transmitting the rebound number to a controller connected to the Schmidt hammer;
measuring an ultrasonic pulse transit time in the concrete surrounding the anchor bolt by using an ultrasonic pulse velocity tester;
measuring an angle of inclination of the plunger with a digital level connected to Schmidt hammer;
correcting the rebound number based on the angle of inclination of the plunger;
transmitting the corrected rebound number to the controller;
estimating the pull out load carrying capacity of the installed anchor bolt by correlating the rebound number with the ultrasonic transit time; and
evaluating the bond quality of the embedded anchor bolt with the concrete.

7. The non-destructive testing method of claim 6 , wherein measuring a rebound number further comprises
contacting, with a distal end of a guide tube, the concrete structure;
contacting the embedded anchor bolt with the convex distal tip of the plunger;
driving an impact mass along a central axis of the Schmidt hammer to impact the plunger;
impacting the anchor bolt with the convex distal tip of the plunger;
measuring the rebound distance of the mass; and
generating a rebound number based on the rebound distance.

8. The non-destructive testing method of claim 6 , wherein measuring an ultrasonic pulse transit time comprises
contacting the concrete at a first location surrounding the anchor bolt with a transmitting transducer;
contacting the concrete at a second location surrounding the anchor bolt and spaced from the first location with a receiving transducer;
generating an ultrasonic pulse with the transmitting transducer at a first time;
receiving the ultrasonic pulse with the receiving transducer at a second time later than the first time, the receiving transducer generating an electrical signal in response to receiving the ultrasonic pulse;
calculating the ultrasonic pulse transit time by subtracting the first time from the second time;
recording the ultrasonic pulse transit time in a memory of the ultrasonic pulse velocity tester; and
displaying the ultrasonic pulse transit time on a display of the ultrasonic pulse velocity tester.

9. The non-destructive testing method of claim 8 , further comprising
transmitting the ultrasonic pulse transit time to a controller connected to the ultrasonic pulse velocity tester, wherein the controller is at least one of connected wirelessly to the ultrasonic pulse velocity tester and connected by wiring to the ultrasonic pulse velocity tester.

10. The non-destructive testing method of claim 9 , wherein estimating the pull out load capacity of the embedded anchor bolt further comprises
receiving the Schmidt hammer rebound number at the controller, wherein the controller includes a database, a memory, a processor, a transceiver and a receiver;
retrieving, from data stored in the database, an embedment length, an anchor bolt diameter and a concrete strength;
combining the Schmidt hammer rebound number, R, with the embedment length, Ld, anchor bolt diameter, Bd, and concrete strength, Cs, to generate a vector x, where x={R, Le, Bd, Cs};
receiving the transit time, TT, from the ultrasonic pulse velocity tester at the controller;
combining the transit time with the with the vector x to generate a vector y, where y={R, Le, Bd, Cs, TT};
matching the vector y with a record from a look up table stored in the database, wherein the lookup table record relates the vector y to a pull out load capacity.

11. The non-destructive testing method of claim 9 , wherein evaluating the bond quality of the embedded anchor bolt with the concrete structure comprises
receiving

Assignees

• Univ Imam Abdulrahman Bin Faisal

Inventors

• Saleem Muhammad

Classifications

• G01N33/383 Primary

  Concrete or cement · CPC title

• G01N2203/0039

  Hammer or pendulum · CPC title

• G01M1/00

  Testing static or dynamic balance of machines or structures · CPC title

• G01N2291/0232

  Glass, ceramics, concrete or stone · CPC title

• G01N29/07

  by measuring propagation velocity or propagation time of acoustic waves · CPC title