A fiberglass beam having a body ( 1 ) thereof being made of fiberglass. A nailing spot thereof is of a thickness (t 1 ) between two to six millimeters. The fiberglass beam also comprises one or several layers of fiberglass-enforced layer ( 2 ) sleeved on the surface of the body ( 1 ). The fiberglass beam obviates the use of wood, and allows for improved service life and enhanced operability.

FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a kind of beam used in field of civil engineering, and more particularly to fiberglass reinforced plastic beams which could be used to substitute conventional wood beams. 
       BACKGROUND OF THE INVENTION 
       [0002]    In field of civil engineering, beams are normally used to support wood formworks, and thus should satisfy the following two requirements at the same time:
       1. The requirement as to mechanics: the beams should possess excellent strength to enable to support wood formworks filled with concrete.   2. The requirements as to function: the beams could be nailed to enable to fix the position of wood formworks, which could prevent the wood formworks from moving due to impact during filling of concrete into the wood formworks.       
 
         [0005]    Since solid wood could satisfy the above two requirements, most of beams are currently made of solid wood. However, the wooden beams consume a plenty of wood, which incurs adverse impact to the environment. Furthermore, the wooden beams are subject to absorbing water, and then their weight will increase, which makes it inconvenient to use. When they are wet after absorbing water, the wooden beams would deform and rot rapidly, which would shorten the service life of the beams. 
         [0006]    Therefore, beams made of metal are developed to substitute wooden beams. Metal beams have excellent strength to support wood formworks filled with concrete. However, the metal beams are too hard to be nailed, which makes it difficult to fix the wood formworks. Thus, it is necessary to provide wooden sheets onto the surfaces of the metal beams to enable to be nailed. In this connection, each metal beam comprises a main body made of metal and wooden sheets attached the surfaces of the main body. Although such kind of metal beams could satisfy the requirements for use, it is unavoidable to use wood to some extent, and thus the deficiencies of wooden beams still exist. 
       SUMMARY OF THE INVENTION 
       [0007]    To overcome the above-mentioned shortcomings, the present invention aims to provide a fiberglass reinforced plastic beam comprising: a main body made of fiberglass reinforced plastic in which the thickness of spots to be nailed of the main body is 2-6 mm; and one or more fiberglass reinforced layers covering the main body. 
         [0008]    The cross section of the main body is in the shape of the letter “I”, the spots to be nailed are an upper wing and a lower wing of the main body, while the thickness of a center support of the main body is 2-15 mm, 
         [0009]    Each fiberglass reinforced layer may comprise two sections covering the left and right sides of the main body respectively, and overlapping with each other at the external surfaces of the upper and lower wings of the main body. 
         [0010]    Or, each fiberglass reinforced layer may also comprise two sections, one covering the left or right side and upper and lower surface of the main body, while the other covering the other side of the main body, and the two sections overlap each other at the side of the upper and lower wings of the main body. 
         [0011]    Or, each fiberglass reinforced layer may also comprise two sections covering the upper and lower parts of the main body respectively, and overlapping each other at both sides of the center support of the main body. 
         [0012]    Furthermore, the cross section of the main body is in the shape of a hollow quadrangle, the spots to be nailed are an upper wall, a lower wall and sidewalls of the main body, and the thickness of each wall is 2-6 mm. 
         [0013]    Or, the cross section of the main body is in the shape of a hollow quadrangle, the spots to be nailed is an upper wall and a lower wall of the main body, and the thickness of both sidewalls is 2-15 mm. 
         [0014]    Each fiberglass reinforced layer may comprise two sections covering the upper and lower parts of the main body respectively, and overlapping each other at both sides of the center support of the main body. 
         [0015]    Furthermore, the main body may include a U-shaped frame and an accessory provided at an opening of the frame, and a protrusion is provided on an internal wall of the frame near the opening thereof for supporting the accessory. Or, the main body may include a U-shaped frame and an accessory provided at an opening of the frame, and a protrusion is provided on an internal wall of the frame near the opening thereof for supporting the accessory, a reinforcing rib is provided within the U-shaped frame between two sidewalls thereof. 
         [0016]    The spots to be nailed are upper and lower plates of the accessory, and the thickness of the upper and lower plates is 2-6 mm. 
         [0017]    Preferably, one or more additional fiberglass reinforced layers could be provided on the surface of the spots to be nailed. 
         [0018]    In the present invention, the fiberglass reinforced layers may be made of fiberglass chopped strand mat, and the main body is manufactured by pultruding matrix together with reinforcement, the matrix is unsaturated polyester, epoxy resin or phenolic resin, while the reinforcement is threads of fiberglass. 
         [0019]    The height of the fiberglass reinforced plastic beam is 50-350 mm, while the width thereof is 30-150 mm. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The present invention will be described in details with reference to the accompanying drawings, which are for illustration purposes only and are not drawn to scale, in which: 
           [0021]      FIG. 1  is a schematic view illustrating a first embodiment of the fiberglass reinforced plastic beam according to the present invention; 
           [0022]      FIG. 2  is a schematic view illustrating the size of a main body of the fiberglass reinforced plastic beam in the first embodiment; 
           [0023]      FIGS. 3-7  are schematic views illustrating the variants of the first embodiment; 
           [0024]      FIG. 8  is a schematic view illustrating a second embodiment of the fiberglass reinforced plastic beam according to the present invention; 
           [0025]      FIG. 9  is a schematic view illustrating the size of a main body of the fiberglass reinforced plastic beam in the second embodiment; 
           [0026]      FIGS. 10-12  are schematic views illustrating the variants of the second embodiment; 
           [0027]      FIGS. 13   a ,  13   b  and  14  are schematic views illustrating a third embodiment of the fiberglass reinforced plastic beam according to the present invention; and 
           [0028]      FIGS. 15   a  and  15   b  are schematic views illustrating a fourth embodiment of the fiberglass reinforced plastic beam according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    Fiberglass reinforced plastic is a kind of well-known material, which is also called glass-reinforced plastic. It is a fiber reinforced polymer made of a matrix reinforced by fiberglass by means of composite technology, in which the plastic matrix could be unsaturated polyester, epoxy resin or phenolic resin. The fiberglass reinforced plastic is so called because of its rigidity. Although it is very rigid, fiberglass reinforced plastic has never been used to manufacture beams, since it is too hard to be nailed. If a part made of fiberglass reinforced plastic needs to be nailed, the thickness of the part should be very thin. However, the thin thickness of the part would deteriorate its load bearing capability. In addition, upon being nailed, the part made of fiberglass reinforced plastic would crack. Thus, fiberglass reinforced plastic is seldom used to manufacture beams in field of civil engineering. In another word, to enable to use fiberglass reinforced plastic to manufacture beams, the part made of fiberglass reinforced plastic should have a thin thickness, and should possess excellent load bearing capability at the same time. Furthermore, the part should prevent from cracking upon being nailed. 
         [0030]      FIG. 1  shows the first embodiment of the fiberglass reinforced plastic beam according to the present invention, which is made of fiberglass reinforced plastic, and the cross section thereof is in the shape of the letter “I”. The fiberglass reinforced plastic beam of the present invention comprises a main body  1  and one or more fiberglass reinforced layers  2  covering the main body  1 . 
         [0031]    As shown in  FIG. 2 , upper and lower wings of the I-shaped main body  1  are used as spots to be nailed, and the thickness t 1  thereof is controlled within a range of 2-6 mm. When the thickness of the part made of fiberglass reinforced plastic is controlled within the aforesaid range, the part is possible to be nailed. Furthermore, the thickness t 2  of a center support of the main body  1  may be 2-15 mm. The height H of the main body of the fiberglass reinforced plastic beam could be 50-350 mm, while the width W thereof may be 30-150 mm. 
         [0032]    The main body of the fiberglass reinforced plastic beam of the present invention could be manufactured by pultruding matrix such as unsaturated polyester, epoxy resin or phenolic resin, together with reinforcement such as threads of fiberglass. 
         [0033]    To prevent the fiberglass reinforced plastic beam from cracking upon being nailed, one or more fiberglass reinforced layers  2  could be covered onto the surface of the main body  1  of the fiberglass reinforced plastic beam. The fiberglass reinforced layers could be fiberglass chopped strand mat or other fiberglass reinforcement. 
         [0034]    As shown in  FIG. 1 , in the first embodiment of the fiberglass reinforced plastic beam, each fiberglass reinforced layer comprises two sections covering the left and right sides of the main body respectively, and overlapping with each other at the external surfaces of the upper and lower wings of the main body. Since reinforced by the fiberglass reinforced layers, the main body of the fiberglass reinforced plastic beam possess better strength, and thus would not crack upon being nailed. 
         [0035]    The fiberglass reinforced plastic beams of the present invention not only could support heavy wood formworks, but also could be nailed to fix the latter. Therefore, it could substitute wooden beams or metal beams completely. Comparing to the conventional wooden beams or metal beams, the fiberglass reinforced plastic beams of the present invention have the following advantages:
       1. Since the fiberglass reinforced plastic beams of the present invention do not need wood, the adverse impact to the environment by cutting a plenty of trees could be avoided.   2. Fiberglass reinforced plastic is waterproof, and thus its service life would not be shorten since it would not absorb water like wooden beams or wooden sheets of metal beams.   3. The weight of such kind of fiberglass reinforced plastic beams is only one third of solid wooden beams or metal beams, and thus fiberglass reinforced plastic beams are lighter and more portable than the latters.   4. Comparing to the cube-shaped solid wooden beams, the configuration of the I-shaped fiberglass reinforced plastic beam is more suitable for hands which make it more convenient for moving manually.       
 
         [0040]      FIG. 3  illustrates a variant of the first embodiment. In this variant, each fiberglass reinforced layer also comprises two sections covering the upper and lower parts of the main body respectively, and overlapping each other at both sides of the center support of the main body. 
         [0041]      FIGS. 5-7  illustrate variants of the fiberglass reinforced plastic beams shown in  FIGS. 1 ,  3  and  4  respectively. Different from the fiberglass reinforced plastic beams shown in  FIGS. 1 ,  3  and  4 , the upper and lower surfaces of fiberglass reinforced plastic beams of  FIGS. 5-7  are covered by one or more additional fiberglass reinforced layers  3 . Therefore, the strength of the spots to be nailed could be enhanced, which could prevent the main bodies of the fiberglass reinforced plastic beams from cracking upon being nailed. 
         [0042]      FIG. 8  illustrates the second embodiment of the fiberglass reinforced plastic beam according to the present invention, which is made of fiberglass reinforced plastic, and the cross section thereof is in the shape of a hollow quadrangle. The fiberglass reinforced plastic beam of the present invention comprises a main body  11  and one or more fiberglass reinforced layer  12  covering the main body  11 . 
         [0043]    As shown in  FIG. 9 , spots to be nailed are upper and lower surfaces of the main body  11  of the hollow-quadrangle-shaped fiberglass reinforced plastic beam whose thickness t 1  is controlled within a range of 2-6 mm. When the thickness of the part made of fiberglass reinforced plastic is controlled within the aforesaid range, the part is possible to be nailed. Furthermore, the thickness t 2  of both sidewalls of the main body  11  may be 2-15 mm. However, to enable the sidewalls to be used as spots to be nailed, the thickness thereof should be controlled within a range of 2-6 mm. The height H of the main body of the fiberglass reinforced plastic beam could be 50-350 mm, while the width W thereof may be 30-150 mm. 
         [0044]      FIG. 10  illustrates a variant of the second embodiment. In this variant, each fiberglass reinforced layer comprises two sections covering upper and lower parts of the main body respectively, and overlapping each other on the surfaces of the sidewalls of the main body. 
         [0045]      FIGS. 11-12  illustrate variants of the fiberglass reinforced plastic beams shown in  FIGS. 8 and 10  respectively. Different from the fiberglass reinforced plastic beams shown in  FIGS. 8 and 10 , upper and lower surfaces of fiberglass reinforced plastic beams of  FIGS. 11-12  are covered by one or more additional fiberglass reinforced layers  13 . Therefore, the strength of the spot to be nailed could be enhanced, which could prevent the main body of the fiberglass reinforced plastic beam from cracking upon being nailed. 
         [0046]      FIGS. 13   a ,  13   b  and  14  illustrate the third embodiment of the fiberglass reinforced plastic beam according to the present invention, which comprises a main body  4  made of fiberglass reinforced plastic and one or more fiberglass reinforced layers  22  and  32  covering the main body  4 . As shown in  FIG. 13   a , the main body  4  includes a U-shaped frame  21  and an accessory  31  provided at the opening of the frame. A protrusion  23  is provided on an internal wall of the frame  21  near the opening thereof, to enable to support the accessory  31 . As shown in  FIG. 13   b , the frame  21  and accessory  31  are covered by the fiberglass reinforced layers  22  and  32  respectively, to enhance the strength of the fiberglass reinforced plastic beam. 
         [0047]    As shown in  FIG. 14 , in the third embodiment, the frame  21  is mainly used to support the accessory, and thus the thickness t 1  of its sidewalls may be 2-15 mm, while the thickness t 2  of its bottom may be 2-15 mm. The height H 1  of the frame  21  could be 30-350 mm, while the width W 1  thereof could be 30-150 mm. Spots to be nailed are upper and lower plates of the accessory  31 . Therefore, the thickness t 6  is controlled within a range of 2-6 mm. The thickness t 7  of the sidewalls and the center support of the accessory  31  may be 2-15 mm. The height H 2  and thickness W 2  of the accessory  31  may be 10-20 mm and 20-146 mm respectively. 
         [0048]    The advantage of the present embodiment is in that when the spots to be nailed should be replaced since the fiberglass reinforced plastic beam is damaged after being nailed for many times, it is only necessary to substitute the accessory rather than the frame. Therefore, the building rubbish could be further reduced, and thus it would be of environment friendly. 
         [0049]      FIGS. 15   a  and  15   b  illustrate the fourth embodiment of the fiberglass reinforced plastic beam according to the present invention. Similar to the third embodiment, the fourth embodiment comprises a main body  5  made of fiberglass reinforced plastic and one or more fiberglass reinforced layers  42  and  52  covering the main body  5 . As shown in  FIG. 15   a , the main body  5  comprises a U-shaped frame  41  and an accessory  51  provided at the opening of the frame. A protrusion  43  is provided on an internal wall of the frame  41  near the opening thereof, to enable to support the accessory  51 . As shown in  FIG. 15   b , the frame  41  and accessory  51  are covered by the fiberglass reinforced layers  42  and  42  respectively, to enhance the strength of the fiberglass reinforced plastic beam. 
         [0050]    Different from the third embodiment, in the fourth embodiment, a reinforcing rib  44  is provided within the U-shaped frame between the two sidewalls thereof, to enhance the strength of the frame  41 . The sizes of the other components of the fourth embodiment are the same as those of the third embodiment, while the thickness of the reinforcing rib  44  may be 2-15 mm. 
         [0051]    The advantage of the present embodiment is in that when the portions to be nailed should be replaced since the fiberglass reinforced plastic beam is damaged after being nailed for many times, it is only necessary to substitute the accessory rather than the frame. Therefore, the building rubbish could be further reduced, and thus it would be of environment friendly. 
         [0052]    Although some embodiments of the present invention have been shown and described with reference to the accompanying drawings, those skilled in the art should understand that various changes and modifications can be made to the embodiments without departing the principles and spirits of the present invention and they still fall into the scope of claims and the equivalent thereof.