Patent Publication Number: US-8117787-B2

Title: Construction support

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Chinese Utility Model Application No. 200820132206.X, filed Aug. 15, 2008, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field 
     Example embodiments relate to a construction support and, more particularly, to a construction support, a length of which can be precisely and easily adjusted to a floor-to-floor height between upper and lower floor slabs, capable of supporting the load of the upper floor slab in a more stable and firm manner and performing dismantlement in a more convenient manner. 
     2. Discussion of Related Art 
     Such a construction support refers to a supporting post (known as a “dongbari” among those skilled in the art in Korea), and is a tool used to support the load of a slab in various buildings. 
     The slab generically refers to a flat concrete mat, and is typically called a floor slab. In ordinary reinforced concrete structures, the slab is surrounded by beams, and the load applied to the slab is distributed among the surrounding beams. Further, in the general case in which a span ranges from 4 m to 5 m, the slab would have a thickness of about 15 cm. 
     Among the slabs, a flat slab is a reinforced concrete slab directly carried on posts without being supported by beams or girders. The flat slab may be arranged by special reinforcing bars, particularly to such a degree that bending strength thereof is maintained at a safe level. 
     For example, as schematically illustrated in  FIG. 1 , many supports  1  are used to support a slab of a building until the slab is poured and then fully cured. 
     These supports have a variety of types from a primitive type such as a wooden support to a length-variable type, and various structures and mechanisms continue to be proposed. Despite being a simple tool, the support is essential to building or civil engineering sites, and is used in a large quantity. As such, the support occupies a part of construction cost, and is a factor that requires much manpower and time for installation and dismantlement. 
       FIG. 2  is an exploded perspective view of a conventional construction support. The conventional support  1  is constructed to connect a lower pipe  10  with an upper pipe  20  using a coupling member  30 . The upper pipe  20  has a relatively smaller diameter than the lower pipe  10 . Thus, the upper pipe  20  may be inserted into the lower pipe  10  to adjust a length of the support. 
     The conventional support  1  of  FIG. 2  has multiple pairs of catch holes  21  spaced apart from each other at regular intervals in an outer circumference of the upper pipe  20  in order to fix the upper pipe  20 . 
     Further, a pair of coupling holes  11  is formed through an outer circumference of one end of the lower pipe  10 . 
     The coupling member  30  is inserted into the coupling holes  11 . 
     The upper pipe  20  is inserted into the lower pipe  10 , and then is pulled to come into contact with a slab. When the catch holes  21  of the upper pipe  20  are aligned with the coupling holes  11  of the lower pipe  10 , the coupling member  30  is inserted into the coupling and catch holes  11  and  21  of the lower and upper pipes  10  and  20 . Thereby, the upper pipe  20  is fixed. 
     Since this conventional support  1  is configured such that the upper pipe  20  is inserted into the lower pipe  10  and the coupling member  30  is inserted and fixed into the aligned coupling and catch holes  11  and  21 , it is substantially difficult to precisely adjust an interval between the slab and the upper pipe  20 . In order to solve this problem, if the interval between the catch holes  21  becomes narrow, the catch hole  21  of the upper pipe  20  has a chance of being damaged by the load of the slab which is applied to the upper pipe  20  in a downward direction. As such, this may compromise safety. 
     Further, since the coupling member  30  is fixed by the insertion whenever the support  1  is installed, the time required for the installation or dismantlement work increases, and thus the accompanied manpower also increases. 
     SUMMARY 
     An example embodiment is directed to provide a construction support, in which an interval between a bottom surface and a slab support surface can be precisely adjusted to support the load of the slab. 
     Another example embodiment is directed to provide a construction support, capable of increasing a supporting force against the load transmitted from a slab to support the load of the slab in a more stable and firm manner when installed. 
     Still another example embodiment is directed to provide a construction support, in which installation and dismantlement can be conveniently performed to reduce work time and accompanied manpower thereof. 
     In example embodiments, a length-adjustable construction support includes: a first pipe; a second pipe having an outer diameter smaller than an inner diameter of the first pipe; an inner stopper coupled to an outer circumference of the second pipe at a predetermined position, and having a plurality of pressure ridges formed on an inner circumference thereof to press and fix the outer circumference of the second pipe, a separation guide flange protruding outward from an outer circumference thereof by a predetermined length, and at least one cutout slot formed in a lengthwise direction thereof; and an outer stopper having a support wall formed on an inner circumference thereof such that the inner stopper is inserted and supported, and a stop step formed at a lower end of the support wall to be supported on the first pipe. 
     The inner stopper may include an inclined surface on an outer circumference thereof such that an outer diameter thereof is gradually reduced in an inserting direction thereof. The support wall of the outer stopper may be inclined corresponding to the inclined surface of the inner stopper. 
     The pressure ridges may be formed in the form of a sawtooth or ratchet. 
     The sawtooth or ratchet form may be inclined in a direction opposite to an inserting direction of the inner stopper. 
     The inner stopper may include a ring retaining groove formed in at least one of upper and lower ends thereof. The ring retaining groove may be fitted with a snap ring. 
     The support may further include an outer cap, an inner circumference of which has a diameter equal to a diameter of an upper outer circumference of the outer stopper to be coupled to the upper outer circumference of the outer stopper, and which has a through-hole in the center thereof to allow the inner stopper inserted into the outer stopper to be inserted. 
     The outer cap may include a threaded part formed on the inner circumference thereof, and the outer stopper may include a first threaded part formed on the upper outer circumference thereof, so that the outer cap is screwed with the outer stopper. 
     The outer cap may include at least one rotating handle formed on the outer circumference thereof at intervals of a predetermined angle. 
     The through-hole may have a diameter smaller than an outer diameter of the separate guide flange. 
     The outer stopper may include at least one keying groove formed in the inner circumference thereof, and the inner stopper may include at least one keying groove formed in the outer circumference thereof to correspond to the keying groove of the outer stopper. The keying grooves may be fitted with an anti-rotation key to prevent the inner stopper from rotating. 
     The anti-rotation key may be integrally formed with the keying groove of the outer stopper. 
     The inner stopper may include a retaining recess that is recessed inward under the separation guide flange with a predetermined width, so that the through-hole of the outer cap is located in the retaining recess to allow the outer cap to move in the retaining recess within the predetermined width. 
     The support may further include: a third threaded part formed on a lower outer circumference of the outer stopper; a precise adjustor having a fourth threaded part formed on an inner circumference thereof to be screwed with the third threaded part, a fifth threaded part formed below the fourth threaded part, and an adjusting knob formed on an outer circumference thereof; and a coupler having a sixth threaded part formed on an outer circumference thereof to be screwed with the fifth threaded part, and coupled to the outer circumference of the first pipe. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail example embodiments thereof with reference to the attached drawings, in which: 
         FIG. 1  is an exploded perspective view of a conventional construction support; 
         FIG. 2  illustrates usage of the conventional construction support; 
         FIG. 3  is an exploded perspective view of a construction support according to an example embodiment of the present invention; 
         FIG. 4  is an exploded cross-sectional view of the construction support according to an example embodiment of the present invention; 
         FIGS. 5(   a ),  5 ( b ) and  5 ( c ) are cross-sectional views for explaining installation and dismantlement of the construction support according to an example embodiment of the present invention; 
         FIG. 6  is an exploded perspective view of a construction support according to another example embodiment of the present invention; 
         FIG. 7  is an exploded perspective view of a construction support according to still another example embodiment of the present invention; and 
         FIG. 8  is a cross-sectional view illustrating installation of the construction support of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     The invention will now be described more fully with reference to the accompanying drawings in which some example embodiments are shown. The invention, however, may be embodied in many alternate forms and should not be construed as limited to only example embodiments set forth herein. Accordingly, it should be understood that there is no intent to limit example embodiments to the particular forms disclosed, but on the contrary, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of the invention. Like numerals, symbols or letters are used to designate like or equivalent elements having the same function throughout the description of the figures. 
     It will be understood that, when referred to as being “connected” or “coupled” to another element, an element may be directly connected or coupled to the other element or indirectly via an intervening element(s). In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there is no intervening element(s) present. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof. 
     Unless otherwise defined herein, all the terms used herein including technical or scientific terms may have the same meaning as terms generally understood by those skilled in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having the same meanings as those in the context of the related art. Unless expressly defined so herein, these terms are not interpreted as ideal or excessively formal meanings. 
     Hereinafter, example embodiments of the invention will be described in greater detail with reference to the accompanying drawings. In the following detailed description, the same reference numeral will be used for the same component or components regardless of the figures in order to facilitate understanding of the example embodiments of the invention. 
       FIG. 3  is an exploded perspective view of a construction support according to an example embodiment of the present invention.  FIG. 4  is an exploded cross-sectional view of the construction support according to an example embodiment of the present invention. 
     Referring to  FIG. 3 , the construction support  100  includes a first pipe  10 , a second pipe  20 , an inner stopper  10 , an outer stopper  120 , and an outer cap  130 . 
     The first pipe  10  has a hollow cylindrical shape and a predetermined length. The first pipe  10  is inserted into the outer stopper  120  at one side thereof, and is located on the ground on the other side thereof. Here, the first pipe  10  may generally be coupled with a jack or a support plate at a lower end thereof. 
     The second pipe  20  has a hollow cylindrical shape and a predetermined length. The second pipe  20  has a smaller outer diameter than an inner diameter of the first pipe  10 . Here, the second pipe  20  may be coupled with a support plate at an upper end thereof to support a structure such as a foam for a slab. 
     Further, the second pipe  20  is located to support the load of the slab poured at one side thereof. Here, a supporting force is generated by pressurization of the inner stopper  110 . 
     Steel pipes having enough strength to be used as a support member of the structure may generally be used for each of the first and second pipes  10  and  20 , but the pipes are not limited to these materials. Further, there is no limitation on the diameters of the first and second pipes  10  and  20 . 
     The inner stopper  110  includes pressure ridges  112 , a separation guide flange  113 , a cutout slot  115 , and a ring retaining groove  114 . 
     The inner stopper  110  is provided with an inclined surface  111 , which is inclined at an outer circumference of the inner stopper  110  at a predetermined angle. Here, the inclined surface  111  is constructed so that an outer diameter of the inner stopper  110  is gradually reduced in an inserting direction thereof, i.e. toward a lower end thereof. 
     The pressure ridges  112  are formed on an entire inner circumference of the inner stopper  110  in a lengthwise direction. Preferably, each pressure ridge  112  may be formed in the form of a sawtooth or ratchet. 
     Each pressure ridge  112  has a predetermined angle of inclination in a direction opposite to that in which the inner stopper  110  is inserted. 
     Here, the ratchet refers to a device that allows linear or rotary motion in only one direction by action of a pawl, while preventing motion in the opposite direction. 
     Further, the pressure ridges  112  serve to press and fix an outer circumference of the second pipe  20  inserted into the inner stopper  110 . 
     The separation guide flange  113  protrudes outward from an upper end of the inner stopper  110  by a predetermined length. 
     The cutout slot  115  is formed in a circumference of the inner stopper  110  in such a manner that the inner stopper  110  is cut out into inner sub-stoppers at intervals of a predetermined central angle. Thus, one or more cutout slots  115  are formed in the lengthwise direction of the inner stopper  110 . 
     The cutout slots  115  may be selectively formed at intervals of 45, 90, 120, or 180 degrees, preferably 90 degrees. 
     The ring retaining groove  114  is formed in at least one of the upper and lower ends of the inner stopper  110 , preferably adjacent to the separation guide flange  113  and spaced from the separate guide flange  113 . Preferably, a snap ring  140  may be fitted into the ring retaining groove  114 . 
     The ring retaining groove  114  and the snap ring  140  integrate the inner sub-stoppers divided from the inner stopper  110  by the cutout slots  115 . The inner stopper  110  integrated by the snap ring  140  has a predetermined resilient force. 
     Further, when the inner stopper  110  is spread outward by the predetermined resilient force, and then the second pipe  20  is inserted into the inner stopper  110  to be surrounded by the pressure ridges  112 , the pressure ridges  112  press the outer circumference of the second pipe  20  due to the snap ring  140 . This pressing force is derived from a predetermined resilient force of the snap ring  140 . Thus, this pressing force is weak, so that the inner stopper  110  can move to a predetermined position by itself or together with the second pipe  20 . 
     The inner stopper  110 , which moves to the predetermined position, is engaged with an inner circumference of the outer stopper  120 . Further, the inner stopper  110  is provided with a retaining recess  118 , which is recessed inward with a predetermined width under the separation guide flange  113 . 
     The outer stopper  120  includes a support wall  121 , a stop step  127 , and a first threaded part  128 . 
     The support wall  121  is formed on an inner circumference of the outer stopper  120 . The support wall  121  is formed to correspond to the inclined surface  111  of the inner stopper  110 , i.e. is constructed so that an inner diameter of the outer stopper  120  is gradually reduced in the inserting direction of the inner stopper  110  at a predetermined angle of inclination. 
     Here, by forming the support wall  121  to correspond to the inclined surface  111  of the inner stopper  110 , the pressure ridges  112  are allowed to press and fix the outer circumference of the second pipe  20  with stronger force as the inner stopper  110  is pressed inward while being inserted into the upper portion of the outer stopper  120 . 
     Further, an average inner diameter of the support wall  121  is equal or similar to an average outer diameter of the inclined surface  111  of the inner stopper  110 . 
     The stop step  127  is formed at a lower end of the support wall  121  such that one end of the first pipe  10  inserted into the outer stopper  120  is caught. 
     Further, the stop step  127  also serves to regulate movement of the inner stopper  110  moving along the support wall  121  above. In detail, the stop step  127  restricts the movement of the inner stopper  110  moving along the support wall  121 , so that a proper pressing force can be applied to the second pipe  20 . 
     Meanwhile, the load of the slab is transmitted to the second pipe  20 . Due to this load, the inner stopper  110  moves along the support wall  121 , so that the pressing force of the pressure ridges  112  of the inner stopper  110  can increase. Thus, unless the outer stopper  120  has the stop step  127 , the second pipe  20  may be damaged by the increased pressing force. 
     In addition, a lower portion of the outer stopper  120  having the stop step  127  has an inner diameter equal or similar to the outer diameter of the first pipe  10 . 
     Here, the first pipe  10  may be forcibly fitted into the outer stopper  120 . 
     The first threaded part  128  is formed on an upper outer circumference of the outer stopper  120 . A thread form of the first threaded part  128  may be selectively applied. 
     The outer cap  130  is provided with a second threaded part  137  on an inner circumference thereof to be screwed with the first threaded part  128 . As with the thread form of the first threaded part  128 , a thread form of the second threaded part  137  may also be selectively applied. 
     Further, the outer cap  130  is provided with a through-hole  138  in the center thereof through which the inner stopper  110  can be inserted. An inner diameter of the through-hole  138  is smaller than an outer diameter of the separation guide flange  113 . 
     In addition, the outer cap  130  is provided with at least one rotating handle  139 , which protrudes from an outer circumference of the outer cap  130 . Preferably, four rotating handles  139  are formed at intervals of 90 degrees. 
     The rotating handles  139  are used to rotate the outer cap  130 . 
     When the outer cap  130  is rotated in the inserting direction of the inner stopper  110 , the inner stopper  110  is further inserted into and fixed in the outer stopper  120  by a rotating force of the outer cap  130 . In contrast, when the outer cap  130  is rotated in the opposite direction, the inner stopper  110  in close contact with the outer stopper  120  is easily separated from the outer stopper  120 . 
     The snap ring  140  is partially cut out. The snap ring  140  is fitted into the ring retaining groove  114 , and provides a predetermined resilient force to the inner stopper  110 . 
       FIGS. 5(   a ),  5 ( b ) and  5 ( c ) are cross-sectional views for explaining installation and dismantlement of the construction support according to an example embodiment of the present invention. 
     A description will be made regarding installation of the construction support with reference to  FIGS. 5(   a ),  5 ( b ) and  5 ( c ). 
     The first pipe  10  is fitted into the lower portion of the outer stopper  120 . Here, a lower inner circumference of the outer stopper  120  has a diameter equal or similar to the outer diameter of the first pipe  10  to be fitted. The first pipe  10  may be forcibly fitted into the outer stopper  120 . Alternatively, the upper outer circumference of the first pipe  10  and the lower inner circumference of the outer stopper  120  may be threaded and screwed with each other. 
     The inner stopper  110  is inserted into the through-hole  138  of the outer cap  130 . In this case, when the snap ring  140  is fitted into the ring retaining groove  114  of the inner stopper  110  that is divided by the cutout slots  115 , the outer diameter of the inner stopper  110  is reduced, so that the inner stopper  110  can be easily inserted into the through-hole  138 . 
     At this time, the through-hole  138  is located in the retaining recess  118  formed under the separation guide flange  113 , and then the second pipe  20  is inserted into the inner stopper  110 . 
     When the second pipe  20  is inserted into the inner stopper  110 , the inner stopper  110  is spread by elasticity of the snap ring  140  according to the outer diameter of the second pipe  20 . 
     Meanwhile, the second pipe  20  is pulled out to adjust a distance to correspond to the slab, and then the inner stopper  110  is inserted into the outer stopper  120 . 
     At this time, as the inner stopper  110  moves into the outer stopper  120  by the inclined surface  111  of the inter stopper  110  and the support wall  121  of the outer stopper  120 , the pressure ridges  112  of the inner stopper  110  firmly fix the second pipe  20  while pressing the outer circumference of the second pipe  20 . 
     Thus, when the second pipe  20  is fixed, the outer cap  130  held in the retaining recess  118  is brought in the inserting direction of the inner stopper  110 , and then is rotated and fastened using the rotating handle  139  formed on the outer cap  130  such that the first threaded part  128  formed on the outer circumference of the outer stopper  120  is screwed with the second threaded part  137  formed on the inner circumference of the outer cap  130 . Thereby, the second pipe  20  may be prevented from being displaced by the load of the slab, and may provide a firm supporting force (see  FIG. 5(   b )). 
     Afterwards, when the slab is completely cured, the construction support  100  is dismantled. To this end, when rotated in the opposite direction, the outer cap  130  presses the separation guide flange  113  (see  FIG. 5(   c )). 
     Here, a pressing force of the separation guide flange  113  is generated by a rotating force of the outer cap  130 , and the generated pressing force is transmitted to the inner stopper  110 , so that the inner stopper  110  is pushed upward and is separated from the outer stopper  120 . At this time, the pressure ridges  112  of the inner stopper  110  release the force applied to the second pipe  20 . Thus, since only the elasticity of the snap ring  140  is provided to the second pipe  20 , the second pipe  20  is pulled downward with weak force, and thus can be easily separated from the slab. 
       FIG. 6  is an exploded perspective view of a construction support according to another example embodiment of the present invention. The example embodiment of  FIG. 6  is different from that of  FIG. 1  in that a precise adjustor  160  and a coupler  170  are further provided between the outer stopper  120  and the first pipe  10 . Thus, the example embodiment of  FIG. 6  is configured so that the second pipe  20  can more precisely come into close contact with the slab by adjustment of the precise adjustor  160 . 
     For the adjustment of the precise adjustor  160 , a third threaded part  129  is formed on a lower outer circumference of the outer stopper  120 . 
     Further, a fourth threaded part  161  is formed on an upper inner circumference of the precise adjustor  160  to be screwed with the third threaded part  129 . A fifth threaded part  162  is formed on a lower inner circumference of the precise adjustor  160  below the fourth threaded part  161 . Here, the fourth threaded part  161  has threads opposite to those of the fifth threaded part  162 . 
     For example, if the fourth threaded part  161  has left-hand threads tightened by counterclockwise rotation, the fifth threaded part  162  has right-hand threads tightened by clockwise rotation. This configuration is designed to vary a length, because the fourth and fifth threaded parts  161  and  162  are tightened or loosened by rotation in opposite directions. 
     Further, the precise adjustor  160  is provided with at least one adjusting knob  163  on an outer circumference thereof. The adjusting knob  163  facilitates rotation of the precise adjustor  160 , thereby allowing the second pipe  20  to be in close contact with the foam for the slab. 
     The coupler  170  is coupled to the upper outer circumference of the first pipe  10 . The coupler  170  has an inner diameter equal or similar to the outer diameter of the first pipe  10 . At this time, the coupler  170  may be coupled with the first pipe  10  by interference fit or fixing means such as welding. 
     Further, the coupler  170  is provided with a sixth threaded part  171  on an outer circumference thereof. The sixth threaded part  171  is screwed with the fifth threaded part  162 . Thus, the sixth threaded part  171  has threads formed in a direction corresponding to threads of the fifth threaded part  162 . 
     Further, the coupler  170  is provided with a stop rim  172  at an upper end thereof such that the upper end of the first pipe  10  inserted into the coupler  170  is caught. 
       FIG. 7  is an exploded perspective view of a construction support according to still another example embodiment of the present invention.  FIG. 8  is a cross-sectional view illustrating installation of the construction support of  FIG. 7 . 
     Referring to  FIGS. 7 and 8 , the construction support  100  includes a first pipe  10 , a second pipe  20 , an inner stopper  110 , an outer stopper  120 , and an outer cap  130 . 
     The first and second pipes  10  and  20  have the same configuration as those described in  FIG. 3 , and thus a detailed description thereof will be omitted in order to avoid redundancy. 
     The inner stopper  110  is provided with a plurality of pressure ridges  112  on an inner circumference thereof. 
     Further, the inner stopper  110  is provided with at least one cutout slot  115  at a predetermined position. Further, the inner stopper  110  is provided with at least one keying groove  116  on an outer circumference thereof in a lengthwise direction thereof to face the cutout slot  115  in a diametrical direction. 
     Here, the cutout slots  115  may be selectively formed at intervals of 45, 90, 120, or 180 degrees, preferably 120 degrees. 
     Thus, the keying groove  116  may be formed in the middle of each inner sub-stopper, into which the inner stopper  110  is divided by the cutout slots  115 . 
     In order to prevent separation between the inner sub-stoppers into which the inner stopper  110  is divided by the cutout slots  115 , at least one ring retaining groove  114  is formed in at least one of upper and lower outer circumferences of the inner stopper  110 . A snap ring  140  is fitted into the ring retaining groove  114 . 
     Here, the ring retaining groove  114  may be formed in each of the upper and lower outer circumferences of the inner stopper  110 . This is because, if the snap ring  140  is fitted into the ring retaining groove  114  at one side alone, the inner sub-stoppers of the inner stopper  110  may move to be separated from each other at the other side where the snap ring  140  is not fitted. 
     Further, in addition to the function of preventing the separation between the inner sub-stoppers of the inner stopper  110 , the snap ring  140  serves to transmit a predetermined resilient force to the pressure ridges  112  when the second pipe  20  moves upward to allow the second pipe  20  to move upward, so that the pressure ridges  112  press the outer circumference of the second pipe  20  by the resilient force, thereby regulating downward movement of the second pipe  20 . 
     In addition, the snap ring  140  is partially cut out. 
     The outer stopper  120  is provided with a support wall  121  on an upper inner circumference thereof such that the inner stopper  110  is inserted and supported. The upper inner circumference of the outer stopper  120  has an average inner diameter equal or similar to the average outer diameter of an inclined surface  111  of the inner stopper  110 . 
     Further, the outer stopper  120  is provided with a stop step  127  on the inner circumference thereof under the support wall  121 . The stop step  127  is formed so that one end of the first pipe  10  inserted into the outer stopper  120  is caught. 
     The lower portion of the outer stopper  120  into which the first pipe  10  is inserted has an inner diameter equal or similar to an outer diameter of the first pipe  10 . 
     The stop step  127  has an inner diameter equal or similar to the inner diameter of the first pipe  10  and greater than the outer diameter of the second pipe  20 . This is because the second pipe  20  is inserted into the first pipe  10  through the stop step  127 . 
     Further, in order to more effectively press and fix the outer circumference of the second pipe  20 , the outer diameter of the inclined surface  111  of the inner stopper  110  and the inner diameter of the support wall  121  of the outer stopper  120  may be formed to be gradually reduced in the inserting direction of the inner stopper  110  at a predetermined angle of inclination. 
     This is because, when the inner stopper  110  moves along the inclined support wall  121  due to the load that is transmitted from the outside (i.e. the slab) to the inner stopper  110  through the second pipe  20 , the inner stopper  110  is subjected to reduction in diameter, i.e. is contracted in an inward direction, thereby making it possible to more effectively press and fix the outer circumference of the second pipe  20 . 
     Further, the support wall  121  is provided with at least one keying groove  126  at a position that corresponds to the keying groove  116  formed in the inclined surface  111  of the inner stopper  110 . 
     At this time, the keying groove  116  of the inner stopper  110  is aligned with the keying groove  126  of the outer stopper  120 , and then an anti-rotation key  150  is inserted into the aligned keying grooves  116  and  126 . As a result, the inner stopper  110  is prevented from rotating in the outer stopper  120 . 
     Here, the anti-rotation key  150  may be fixed by a fastening member, which is inserted into a through-hole bored through the outer stopper  120  to pass through the keying groove  126 . 
     Further, the anti-rotation key  150  may be integrally formed with the inner circumference of the outer stopper  120 . 
     In addition, the outer cap  130  is coupled with an upper end or an upper end surface of the outer stopper  120  such that the inner stopper  110  placed in the outer stopper  120  does not escape from the outer stopper  120  to the outside. 
     At this time, the outer cap  130  is coupled with the outer stopper  120  by fastening members such as screws or by threads. In the latter case, the outer cap  30  is provided with a second threaded part  137  on an inner circumference thereof, and the outer stopper  120  is provided with a first threaded part  128  on an outer circumference of the upper end thereof. 
     Alternatively, the outer cap  130  may be provided with a hook step to be hooked on the outer circumference of the upper end of the outer stopper  120 . 
     As described above, the construction support has the following effects. 
     First, when a second pipe is precisely adjusted to be in contact with a foam for a slab, and then an inner stopper coupled to the second pipe moves to be coupled inside an outer stopper, pressure ridges formed on the inner stopper press and fix an outer circumference of the second pipe, so that the second pipe is positioned and fixed to the foam for the slab in a more precise manner. Thus, the construction support can more effectively provide a supporting force to the slab. 
     Second, the pressure ridges of the inner stopper are formed in the form of a ratchet, and press and fix the outer circumference of the second pipe, so that the second pipe to which the load transmitted from the slab is applied is not easily moved in the direction in which the load is applied. Thus, the construction support can provide a firm supporting force to the slab and prevent accidents. 
     Third, an outer cap coupled to the outer circumference of the outer stopper is turned, thereby pressing the inner stopper in an inserting direction. Otherwise, the outer cap is turned in the opposite direction, thereby pressing a separation guide flange to easily separate the inner stopper from the outer stopper. Thus, installation and dismantlement of the construction support can be performed in a more convenient manner to contribute to reduction of personnel expenses. 
     While the invention has been shown and described with reference to certain example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.