Abstract:
A gamma ray, an X-ray or an ionizing irradiation penetrates through a steel bar in a reinforced concrete structure. An image of the steel bar is thus projected on a film. Through geometric relationships between the image and the steel bar itself, the size of the steel bar is calculated. The size of the steel bar obtained according to the present invention is reliable and accurate. And the data obtained can be used for structure safety.

Description:
FIELD OF THE INVENTION  
       [0001]    The present invention relates to measuring a steel bar size; more particularly, relates to computing a size of a steel bar in a structure with improved reliability and accuracy as a reference for a structure safety. 
       DESCRIPTION OF THE RELATED ARTS 
       [0002]    To obtain structure safety, examining steel bar in structure with reliability and accuracy is more and more important. However, a reinforced concrete structure having steel bar is an uneven composite material of steel bar, concrete, sand, aggregate, water and admixture, so that examinations done by using stress waves or through electromagnetism principles still face some difficulties. 
         [0003]    Concerning examining steel bar in a structure, electromagnetism principles are usually used; yet their accuracies are so affected by permeability, conductivity, steel bar interval and steel bar construction that difficulties and errancies in examinations increase. 
         [0004]    For example, a steel bar detector using eddy current is developed. A detector having an alternating wire coil is located near a detected steel bar protecting layer to produce a number of eddy-like currents through electromagnetic induction at an alternating magnetic field of the steel bar. And, by the changes in signals of eddy currents, a position and a size of the steel bar are detected. Yet, in places having multiple steel bars or jointing steel bar, interferences to electromagnetic induction occur with the neighboring steel bars and so detection using electromagnetic induction would fail. Thus, a structure safety is not ensured. Hence, the prior arts do not fulfill users&#39; requests on actual use. 
       SUMMARY OF THE INVENTION  
       [0005]    The main purpose of the present invention is to irradiating a gamma ray by a radiation source to project an image of a steel bar, whose position in a structure is acquired in advance, on an imaging device for computing a size of the steel bar through geometric relationships between the image of the steel bar and the steel bar itself. 
         [0006]    Another purpose of the present invention is to compute the size of the steel bar with improved reliability and accuracy as a reference for a structure safety 
         [0007]    To achieve the above purposes, the present invention is a device for measuring a size of a steel bar in a structure and a method thereof, comprising a radiation source, an imaging device and a computing module, where, through a gamma ray irradiated from the radiation source, a steel bar in a structure, whose position is obtained in advance, has its image projected on the imaging device; and a size of the steel bar is thus computed through geometric relationships between the image of the steel bar and the steel bar itself with improved reliability and accuracy as a reference for a structure safety. Accordingly, a novel device for measuring a size of a steel bar in a structure and a method thereof are obtained. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0008]    The present invention will be better understood from the following detailed description of the preferred embodiment according to the present invention, taken in conjunction with the accompanying drawing, in which 
           [0009]      FIG. 1  is the flow view showing the preferred embodiment according to the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0010]    The following description of the preferred embodiment is provided to understand the features and the structures of the present invention. 
         [0011]    Please refer to  FIG.1 , which is a flow view showing a preferred embodiment according to the present invention. As shown in the figure, the present invention is a device for measuring a size of a steel bar in a structure and a method thereof. The device for measuring a size of a steel bar in a structure comprises a radiation source  11 , an imaging device  12  and a computing module (not shown in the figure), where a size of a steel bar  2 , whose position in a reinforced concrete structure  1  is acquired in advance, is computed with improved reliability and accuracy as a reference for a structure safety. 
         [0012]    The radiation source  11  is located outside of the reinforced concrete structure and is a gamma ray, an X-ray or an ionizing radiation source The imaging device  12  is adhered to a horizontal surface of the reinforced concrete structure  1 ; and is located at a place corresponding to the radiation source  11  to receive a projected image of the steel bar by using the radiation source  11 . The imaging device  12  is a film; or a sensor, which is further connected to a display to display the projected image of the steel bar with location data. 
         [0013]    On using the present invention, the radiation source  11  is deposed outside of the reinforced concrete structure  1 . A gamma ray is irradiated by the radiation source  11  to project an image of the steel bar  2  on the imaging device  12 . And, through geometric relationships between the image of the steel bar  2  and the steel bar  2  itself, the size of the steel bar  2  is computed. 
         [0014]    Thus, the computing module computes the steel bar size through the following steps: 
         [0015]    (a) Locations of points are obtained, including a point of the radiation source  11  (X); a point (C) on the horizontal surface of the reinforced concrete structure  1 ; and a first edge point (B′) together with a second edge point (A′) on edge of the image of the steel bar  2  projected on the imaging device  12 , where the X point is perpendicular to the C point on the horizontal surface of the reinforced concrete structure  1  the X point, the B′ point and the A′ point are on the same line; the B′ point is at the same side as the X point; and, the A′ point is a corresponding point to the B′ point at the other side of the image of the steel bar  2 . 
         [0016]    (b) A center of the steel bar  2  (X′) is perpendicular to a point (D) on a line segment (XC)  32  between the X point and the C point; and a length of a line segment (XD)  31  between the X point and the D point is pre-obtained. With the pre-obtained length of the XD line segment  31 , lengths of line segments are measured, including a length of the XC line segment  32 ; a length of a line segment  33  (B′C) between the B′ point and the C point; and a length of a line segment  34  (A′C) between the A′ point and the C point. 
         [0017]    (c) In a triangle having vertex points of X, C and A′, 
         [0000]    
       
         
           
             
               tan 
                
               
                 ( 
                 
                   
                     θ 
                     1 
                   
                   + 
                   
                     θ 
                     2 
                   
                 
                 ) 
               
             
             = 
             
               
                 
                   
                     A 
                     ′ 
                   
                    
                   C 
                 
                 XC 
               
               . 
             
           
         
       
     
         [0000]    Therein, a first angle  111  (θ 1 ) together with a second angle  112  (θ 2 ) has a tangent value equivalent to the length of the A′C line segment  34  divided by the length of the XC line segment  32 . The value of the θ 1  angle  111  together with the θ 2  angle  111  (θ 1 +θ 2 ) is thus computed through the tangent function, where the θ 1  angle  111  has an angle side of the XC line segment  32  and the other angle side of a line segment (XB′) between the X point and the B′ point; and where the second angle  112  has an angle side of the XB′ line segment and the other angle side of a line segment (XA′ ) between the X point and the A′ point. 
         [0018]    (d) In a triangle having vertex points of X, C and B′, 
         [0000]    
       
         
           
             
               tan 
                
               
                 ( 
                 
                   θ 
                   1 
                 
                 ) 
               
             
             = 
             
               
                 
                   CB 
                   ′ 
                 
                 XC 
               
               . 
             
           
         
       
     
         [0000]    Therein, the θ 1  angle  111  has a tangent value equivalent to the length of the B′C line segment  33  divided by the length of the XC line segment  32 . The value of the θ 1  angle  111  is thus computed through the tangent function; and a value of the θ 2  angle  112  is obtained by deducting the value of the θ 1  angle  111  from the value of the θ 1 +θ 2  angle  111 + 112 . 
         [0019]    (e ) In a triangle having vertex points of X, D and X′, 
         [0000]    
       
         
           
             
               cos 
                
               
                 ( 
                 
                   
                     θ 
                     1 
                   
                   + 
                   
                     
                       θ 
                       2 
                     
                     2 
                   
                 
                 ) 
               
             
             = 
             
               
                 XD 
                 
                   XX 
                   ′ 
                 
               
               . 
             
           
         
       
     
         [0000]    Therein, the θ 1  angle  111  together with an abiding half of the θ 2  angle  112   
         [0000]    
       
         
           
             ( 
             
               
                 θ 
                 1 
               
               + 
               
                 
                   θ 
                   2 
                 
                 2 
               
             
             ) 
           
         
       
     
         [0000]    has a cosine value equivalent to the length of the XD line segment  32  divided by a length of a line segment  35  (XX′) between the X point and the X′ point. The length of the XX′ line segment  35  is thus computed through the cosine function. 
         [0020]    (f) And, in a triangle having vertex points of X, A and X′, 
         [0000]    
       
         
           
             
               sin 
                
               
                 ( 
                 
                   
                     θ 
                     2 
                   
                   2 
                 
                 ) 
               
             
             = 
             
               
                 
                   
                     X 
                     ′ 
                   
                    
                   A 
                 
                 
                   XX 
                   ′ 
                 
               
               . 
             
           
         
       
     
         [0000]    Therein, a point (A) on the XA′ line segment is perpendicularly corresponding to the X′ point; and, the other half of the θ 2  angle 
         [0000]    
       
         
           
             112 
              
             
               ( 
               
                 
                   θ 
                   2 
                 
                 2 
               
               ) 
             
           
         
       
     
         [0000]    has a sine value equivalent to a length of a line segment between the X′ point and the A point divided by the length of the XX′ line segment. A length of the X′A line segment, a semi-diameter of the steel bar  2 , is thus computed through the sine function. Accordingly, a size of the steel bar  2  is obtained by doubling the length of the X′A line segment. 
         [0021]    To sum up, the present invention is a device for measuring a size of a steel bar in a structure and a method thereof, where a size of a steel bar, whose position in a structure is acquired in advance, is computed with improved reliability and accuracy as a reference for a structure safety. 
         [0022]    The preferred embodiment herein disclosed is not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention