Patent Publication Number: US-2022220677-A1

Title: Installation method of bent cap for mutually restraining adjacent pier studs in prefabricated and assembled bridge

Description:
BACKGROUND 
     Technical Field 
     The disclosure relates to a construction field of prefabricated and assembled bridges, and in particular, relates to an installation and construction method for pier studs and bent caps in a prefabricated and assembled bridge in highway bridge engineering. 
     Description of Related Art 
     At present, fully assembled bridges are becoming the development trend of bridge construction. The pier studs, bent caps, and other components are prefabricated in factory and assembled on site, and in this way, the level of mechanized operation may be significantly improved, and the construction progress is accelerated while improving quality. Further, the improvement of construction efficiency of the fully assembled bridges may greatly reduce the interference to traffic and is beneficial to environmental protection as well. 
     Regarding the installation and construction of prefabricated and assembled pier studs and bent caps in highway bridge engineering, the bent cap construction is carried out after the pier studs are fixed. The accuracy of the spatial position and state of the pier studs are important for the installation quality of the prefabricated bent caps. Regarding the prefabricated pier studs, accurate positioning is required so that the accuracy of spatial position of the pier studs may be ensured. Nevertheless, in the related art, it is difficult to ensure the degree of matching between the pier studs and the bent caps in a construction method in which each single stud of the prefabricated pier studs is individually adjusted and installed one by one. Once installation deviation occurs in the prefabricated pier studs, the bent caps may not be aligned and installed, which may greatly increase the construction costs and delay the construction period due to rework. 
     SUMMARY 
     Summary of Disclosure 
     In order to prevent the problems found in the related art from occurring, the disclosure provides an installation method of a bent cap for mutually restraining adjacent pier studs in a prefabricated and assembled bridge with an aim to improve construction efficiency of bent cap installation and ensure engineering quality. 
     The technical solution adopted by the disclosure includes the following. 
     The disclosure provides an installation method of a bent cap for mutually restraining adjacent pier studs in a prefabricated and assembled bridge. 
     The pier studs are prefabricated pier studs, and a top portion of each of the prefabricated pier studs is provided with pier stud pre-embedded steel bars. The pier stud pre-embedded steel bars are evenly distributed into a circular ring shape on the top portion of each of the prefabricated pier studs and form a pier stud pre-embedded steel bar ring with a radius r. 
     The bent cap is a prefabricated bent cap, and two ends of the prefabricated bent cap are pre-embedded with bent cap pre-embedded sleeves. Vertical grouting ducts are provided on a top portion of the prefabricated bent cap to communicate with the bent cap pre-embedded sleeves. The bent cap pre-embedded sleeves on the two ends of the prefabricated bent cap are evenly distributed into a circular ring shape at each end to form a bent cap pre-embedded sleeve ring with a radius r. 
     The bent cap pre-embedded sleeves in the bent cap pre-embedded sleeve ring correspond to the pier stud pre-embedded steel bars in the pier stud pre-embedded steel bar ring one to one, such that the pier stud pre-embedded steel bars may be inserted into the bent cap pre-embedded sleeves of corresponding positions for anchorage. 
     A bent cap mold base is configured as follows. 
     Limiting steel rings are fixedly arranged at two ends of a rectangular frame, and steel bar sleeves are vertically arranged in the limiting steel rings. The steel bar sleeves are evenly distributed into a circular ring shape in each limiting steel ring and form a steel bar sleeve ring with a radius r. A center-to-center distance of the steel bar sleeve rings at the two ends and a center-to-center distance of the bent cap pre-embedded sleeve rings at the two ends in the prefabricated bent cap are set to be identical. Positions of the steel bar sleeves in the steel bar sleeve ring are set to correspond to positions of the bent cap pre-embedded sleeves in the bent cap pre-embedded sleeve ring of the corresponding end one to one. 
     The installation method of the bent cap is performed in constructed pile top cup bearing platforms through the following steps. 
     In step 1, through hoisting, the prefabricated pier studs are placed in two adjacent pile top cup bearing platforms, and a center distance and a plane position between the two prefabricated pier studs are preliminarily adjusted. 
     In step 2: the cap bent mold base is hoisted on the top portions of the two prefabricated pier studs, such that the pier stud pre-embedded steel bars protruding from the top portions of the two prefabricated pier studs are correspondingly inserted into the steel bar sleeves at two ends of the bent cap mold base one by one. If the pier stud pre-embedded steel bars in the two prefabricated pier studs and the steel bar sleeves at the two ends of the bent cap mold base are not aligned due to deviation, the prefabricated pier studs are lifted again by a crane, the center distance and/or the plane position between the two prefabricated pier studs are readjusted until the pier stud pre-embedded steel bars in the two prefabricated pier studs are correspondingly inserted into the vertical steel bar sleeves at the two ends of the bent cap mold base one by one, such that the adjacent two prefabricated pier studs are limited in the bent cap mold base. 
     In step 3, heights and perpendicularity of the adjacent two prefabricated pier studs are adjusted to satisfy design needs, and the prefabricated pier studs are kept in a state which satisfies the design needs. 
     In step 4, anchorage is performed between each of the pile top cup bearing platforms and the corresponding prefabricated pier stud to complete assembly of the prefabricated pier studs. 
     In step 5, the bent cap mold base is removed, the bent cap mold base is replaced with the bent cap, and the pier stud pre-embedded steel bars protruding from the top portions of the prefabricated pier studs are inserted into the bent cap pre-embedded sleeves pre-embedded in the bent cap one by one. 
     In step 6, grouting is performed through the grouting ducts on the bent cap, anchorage is performed between the prefabricated pier studs and the prefabricated bent cap, and assembly of the prefabricated bent cap is completed. 
     The installation method of the bent cap for mutually restraining the adjacent pier studs in the prefabricated and assembled bridge provided by the disclosure further includes the following. 
     In step 3, an auxiliary adjustment mechanism is arranged to adjust the height and perpendicularity of each prefabricated pier stud, and a structure of the auxiliary adjustment mechanism is provided as follows. 
     Top support mechanisms are arranged between a top surface of each pile top cup bearing platform and an outer side wall of each prefabricated pier stud. The top support mechanisms are evenly distributed in at least three groups around the outer side wall of the prefabricated pier stud. Each group of the top support mechanisms may independently adjust a top support height thereof, and adjustment of the height and/or perpendicularity of the pier stud is achieved through adjusting the top support height of the top support mechanisms of one group or plural groups. 
     The installation method of the bent cap for mutually restraining the adjacent pier studs in the prefabricated and assembled bridge provided by the disclosure further includes the following. A structure of each of the top support mechanisms is that: a jack is provided on the top surface of each pile top cup bearing platform. A reaction frame with a horizontal support surface is provided on a corresponding position of the outer side wall of each prefabricated pier stud, and the jack is supported between the top surface of the pile top cup bearing platform and the support surface of the reaction frame. 
     The installation method of the bent cap for mutually restraining the adjacent pier studs in the prefabricated and assembled bridge provided by the disclosure further includes the following. The reaction frame is formed by a vertical universal beam and a horizontal universal beam. The vertical universal beam is attached to the outer side wall of the prefabricated pier stud and is attached to the outer side wall of the prefabricated pier stud through flange slabs separately disposed on two sides of a web of the vertical universal beam. One end of the horizontal universal beam abuts against the web of the vertical universal beam and is fixedly connected to the vertical universal beam, and a bottom surface of a lower flange slab in the horizontal universal beam is the support surface of the reaction frame. 
     The installation method of the bent cap for mutually restraining the adjacent pier studs in the prefabricated and assembled bridge provided by the disclosure further includes the following. A fixed structure of the arranged reaction frame is that: a web reserved hole is provided on the web of the vertical universal beam. Pier stud reserved holes are radially and horizontally arranged in each prefabricated pier stud. One end of a steel rod is inserted into one of the pier stud reserved holes, and the other end of the steel rod penetrates through the web reserved hole in the vertical universal beam and is disposed on a top surface of an upper flange slab of the horizontal universal beam. 
     The installation method of the bent cap for mutually restraining the adjacent pier studs in the prefabricated and assembled bridge provided by the disclosure further includes the following. The fixed structure of the reaction frame is further provided with a lower-layer fixed structure formed by: a lower-layer web reserved hole, lower-layer pier stud reserved holes, and a lower-layer steel rod. The lower-layer fixed structure is located at a position that does not interfere with the horizontal universal beam. One end of the lower-layer steel rod is inserted into one of the lower-layer pier stud reserved holes of the prefabricated pier stud, and the other end of the lower-layer steel rod is directly disposed in the lower-layer web reserved hole in the vertical universal beam. 
     The installation method of the bent cap for mutually restraining the adjacent pier studs in the prefabricated and assembled bridge provided by the disclosure further includes the following. 
     Performing anchorage between each of the pile top cup bearing platforms and the corresponding prefabricated pier stud in step 4 further includes the following steps. 
     A pier stud metal bellow is pre-embedded on an outer circumferential surface of a lower section of the prefabricated pier stud, and a pier stud installation section whose outer circumferential surface is bellow-shaped is formed. 
     In a cup mouth of each pile top cup bearing platform, a cup metal bellow is pre-embedded on a wall surface of a stud chamber, and a socket whose stud chamber wall surface is bellow-shaped is formed. A central steel pad is pre-embedded on a bottom surface of the stud chamber. 
     The pier stud installation section is placed in the socket, an annular grouting chamber is formed between circumferential surfaces of each other, and a bottom plane grouting chamber is formed on a bottom surface. A high-strength grouting material is injected in the annular grouting chamber and the bottom plane grouting chamber to achieve the anchorage between the pile top cup bearing platform and the corresponding prefabricated pier stud. 
     The installation method of the bent cap for mutually restraining the adjacent pier studs in the prefabricated and assembled bridge provided by the disclosure further includes the following. Both the pier stud metal bellow and the cup metal bellow adopt galvanized metal bellows. A thickness of the annular grouting chamber is 50 mm, and a thickness of the bottom plane grouting chamber is 20 mm. 
     Compared to the related art, advantages of the disclosure include the following. 
     1. The bent cap mold base is configured in the form of the bent cap in the disclosure. In the installation process, the cap bent mold base is hoisted on the top portions of the adjacent two prefabricated pier studs, such that the pier stud pre-embedded steel bars protruding from the top portions of the two prefabricated pier studs are correspondingly inserted into the steel bar sleeves at the two ends of the bent cap mold base one by one. The adjacent two prefabricated pier studs are limited in the bent cap mold base, so that the degree of matching between the pier studs and the bent cap is effectively ensured through the form of mutual restraint of adjacent pier studs through the use of the bent cap mold base. The situation that the bent cap may not be aligned and installed is thus prevented from occurring, construction efficiency of bent cap installation is significantly improved, and engineering quality is also ensured. 
     2. The auxiliary adjustment mechanism is provided in the disclosure and is arranged to adjust the height and perpendicularity of each prefabricated pier stud. In this way, the perpendicularity and height of the prefabricated pier stud being placed into the bearing platform cup may be quickly and effectively adjusted. 
     3. A high-strength bonding surface is formed between the pier stud installation section and the socket of the pile top cup bearing platform by using the high-strength grouting material in the disclosure. In this way, consolidation between the pier stud installation section and the socket is achieved, the secondary wet connection of the cast-in-place concrete is avoided, and a quick construction process is provided. 
     4. Consolidation of the high-strength grouting material is implemented between the pier stud installation section whose outer circumferential surface is bellow-shaped and the socket whose stud chamber wall surface is bellow-shaped. In this way, the bonding force between the combined members is significantly improved, and the structure is ensured to be firm and stable. 
     5. The auxiliary adjustment mechanism and the bent cap mold base in the disclosure may be recycled after being removed, which is conducive to resource saving. 
     Summary of Disclosure 
     Technical Problems 
     Solution to Problems 
     Beneficial Effects of Disclosure 
     Brief Description of Drawings 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a structure formed by pier studs and a bent cap in the disclosure. 
         FIG. 2  is a schematic view of  FIG. 1  taken along line A-A. 
         FIG. 3  is a schematic view of a bent cap mold base in the disclosure. 
         FIG. 4  is a schematic front view of an auxiliary adjustment mechanism in the disclosure. 
         FIG. 5  is a schematic top view of the auxiliary adjustment mechanism in the disclosure. 
         FIG. 6  is a schematic view of a structure of a reaction frame in the disclosure. 
         FIG. 7  is a schematic view of a matching structure between a pile top cup bearing platform and a prefabricated pier stud in the disclosure. 
     
    
    
     Reference numerals provided in the drawings include: pile top cup bearing platform  1 , prefabricated pier stud  2 , reaction frame  3 , steel rod  4 , lower-layer steel rod  4   a,  horizontal universal beam  5 , vertical universal beam  6 , web reserved hole  7 , lower-layer web reserved hole  7   a,  jack  8 , consolidation surface  9 , circular pad  10 , pile foundation  11 , rectangular frame  12 , limiting steel ring  13 , central steel pad  14 , pier stud pre-embedded steel bar  15 , steel backing plate  16 , grouting duct  17 , steel bar sleeve  18 , bent cap pre-embedded sleeve  19 , pier stud reserved hole  20 , lower-layer pier stud reserved hole  20   a,  prefabricated bent cap  22 , pier stud metal bellow  23 , and cup metal bellow  24 . 
     DESCRIPTION OF THE EMBODIMENTS 
     Description of the Embodiments 
     With reference to  FIG. 1  and  FIG. 2 , in this embodiment, pier studs are prefabricated pier studs  2 . A top portion of each of the prefabricated pier studs  2  is provided with protruding pier stud pre-embedded steel bars  15 , and the pier stud pre-embedded steel bars  15  are evenly distributed into a circular ring shape on the top portion of each of the prefabricated pier studs  2  and form a pier stud pre-embedded steel bar ring with a radius r. A bent cap is a prefabricated bent cap  22 , and two ends of the prefabricated bent cap  22  are respectively pre-embedded with bent cap pre-embedded sleeves  19 . Steel bellows may be adopted to be used as the bent cap pre-embedded sleeves  19 , and the use of the bellow structure may further enhance bonding and firmness between the pier stud pre-embedded steel bars  15  and the bent cap pre-embedded sleeves  19 . Vertical grouting ducts  17  are provided on a top portion of the prefabricated bent cap  22  to communicate with the steel bar connection sleeves  19 , and the bent cap pre-embedded sleeves  19  on the two ends of the prefabricated bent cap are evenly distributed into a circular ring shape at each end to form a bent cap pre-embedded sleeve ring with a radius r. The bent cap pre-embedded sleeves  19  in the bent cap pre-embedded sleeve ring correspond to the pier stud pre-embedded steel bars  15  in the pier stud pre-embedded steel bar ring one to one, such that the pier stud pre-embedded steel bars  15  may be inserted into the bent cap pre-embedded sleeves  19  of corresponding positions for anchorage. 
     With reference to  FIG. 1 ,  FIG. 2 , and  FIG. 3 , a bent cap mold base in this embodiment is configured as follows. 
     Limiting steel rings  13  are fixedly arranged at two ends of a rectangular frame  12  of a steel structure, and steel bar sleeves  18  are vertically arranged in the limiting steel rings  13 . The steel bar sleeves  18  are evenly distributed into a circular ring shape in each limiting steel ring  13  and form a steel bar sleeve ring with a radius r. A center-to-center distance of the steel bar sleeve rings at the two ends and a center-to-center distance of the bent cap pre-embedded sleeve rings at the two ends in the prefabricated bent cap are set to be identical. Positions of the steel bar sleeves  18  in the steel bar sleeve ring are set to correspond to positions of the bent cap pre-embedded sleeves  19  in the bent cap pre-embedded sleeve ring of the corresponding end one to one. 
     An installation method of a bent cap for mutually restraining adjacent pier studs in a prefabricated and assembled bridge provided by this embodiment is performed in constructed pile top cup bearing platforms  1  through the following steps. 
     In step 1, the pile top cup bearing platforms  1  are formed on pile foundations  11 , the prefabricated pier studs  2  are placed in two adjacent pile top cup bearing platforms  1  through hoisting, and a center distance and a plane position between the two prefabricated pier studs  2  are preliminarily adjusted. 
     In step 2: the cap bent mold base is hoisted on the top portions of the two prefabricated pier studs  2 , such that the pier stud pre-embedded steel bars  15  protruding from the top portions of the two prefabricated pier studs are correspondingly inserted into the steel bar sleeves  18  at two ends of the bent cap mold base one by one. If the pier stud pre-embedded steel bars  15  in the two prefabricated pier studs and the steel bar sleeves  18  at the two ends of the bent cap mold base are not aligned due to deviation, the prefabricated pier studs are lifted again by a crane, the center distance and/or the plane position between the two prefabricated pier studs are readjusted until the pier stud pre-embedded steel bars  15  in the two prefabricated pier studs are correspondingly inserted into the vertical sleeves at the two ends of the bent cap mold base one by one, such that the adjacent two prefabricated pier studs  2  are limited in the bent cap mold base based on design needs. 
     In step 3, heights and perpendicularity of the adjacent two prefabricated pier studs  2  are adjusted to satisfy the design needs, and the prefabricated pier studs  2  are kept in a state which satisfies the design needs. 
     In step 4, anchorage is performed between each of the pile top cup bearing platforms  1  and the corresponding prefabricated pier stud  2  to complete assembly of the prefabricated pier studs  2 . 
     In step 5, the bent cap mold base is removed, the bent cap mold base is replaced with the bent cap, steel backing plates  16  are placed between the top portions of the pier studs and the bent cap, and the pier stud pre-embedded steel bars  15  protruding from the top portions of the prefabricated pier studs are inserted into the bent cap pre-embedded sleeves  19  pre-embedded in the bent cap one by one. 
     In step 6, grouting is performed through the grouting ducts  17  on the bent cap, anchorage is performed between the prefabricated pier studs  2  and the prefabricated bent cap  22 , and assembly of the prefabricated bent cap  22  is thus completed. 
     In specific implementation, step 3 further includes the following step. An auxiliary adjustment mechanism is arranged to adjust the height and perpendicularity of each prefabricated pier stud  2 . 
     A structure of the auxiliary adjustment mechanism shown in  FIG. 4 ,  FIG. 5 , and  FIG. 6  is that: top support mechanisms are arranged between a top surface of each pile top cup bearing platform  1  and an outer side wall of each prefabricated pier stud  2 . The top support mechanisms are evenly distributed in at least three groups around the outer side wall of the prefabricated pier stud  2 . Each group of the top support mechanisms may independently adjust a top support height thereof, and adjustment of the height and/or perpendicularity of the pier stud  2  is achieved through adjusting the top support height of the top support mechanisms of one group or plural groups. In this embodiment, four groups of the top support mechanisms distributed in a cross shape are provided, and the top support mechanisms at four positions may independently adjust their respective top support heights. According to spatial position information of the prefabricated pier stud  2  fed back by a total station, the top support heights of the top support mechanisms at the corresponding positions are adjusted, such that the pier stud may meet the perpendicularity and height requirements, and spatial position of the pier stud may be ensured to be accurate. 
     A structure of each of the top support mechanisms is that a jack  8  is provided on the top surface of each pile top cup bearing platform  1 . A reaction frame  3  having a horizontal support surface is provided on a corresponding position of the outer side wall of the prefabricated pier stud  2 , and the jack  8  is supported between the top surface of the pile top cup bearing platform  1  and the support surface of the reaction frame  3 . 
     As shown in  FIG. 6 , the reaction frame  3  is formed by a vertical universal beam  6  and a horizontal universal beam  5 . The vertical universal beam  6  is attached to the outer side wall of the prefabricated pier stud  2  and is attached to the outer side wall of the prefabricated pier stud  2  through flange slabs separately disposed on two sides of a web of the vertical universal beam  6 . 
     One end of the horizontal universal beam  5  abuts against the web of the vertical universal beam  6  and is fixedly connected to the vertical universal beam  6 , and a bottom surface of a lower flange slab in the horizontal universal beam  5  is the support surface of the reaction frame  5 . 
     A fixed structure of the arranged reaction frame  3  is that: a web reserved hole  7  is provided on the web of the vertical universal beam  6 . As shown in  FIG. 7 , pier stud reserved holes  20  are radially and horizontally arranged in the prefabricated pier stud  2 . One end of a steel rod  4  is inserted into one of the pier stud reserved holes  20 , and the other end of the steel rod  4  penetrates through the web reserved hole  7  in the vertical universal beam  6  and is disposed on a top surface of an upper flange slab of the horizontal universal beam  5 . 
     In specific implementation, in order to provide structural stability, the fixed structure of the reaction frame  3  is further provided with a lower-layer fixed structure formed by: a lower-layer web reserved hole  7   a,  lower-layer pier stud reserved holes  20   a,  and a lower-layer steel rod  4   a.  The lower-layer fixed structure is located at a position that does not interfere with the horizontal universal beam  5 . One end of the lower-layer steel rod  4   a  is inserted into one of the lower-layer pier stud reserved holes  20   a  of the prefabricated pier stud, and the other end of the lower-layer steel rod  4   a  is directly disposed in the lower-layer web reserved hole  7   a  in the vertical universal beam  6 . 
     In addition, a center of the jack  8  should be as close as possible to the prefabricated pier stud  2  when operating conditions are met, so as to reduce concrete damage when the steel rod is inserted into a mouth portion. A circular pad  10  with a larger area than that of a bottom portion of the jack  8  may be placed on the bottom portion of the jack  8 , so that a force may be evenly received. 
     In this embodiment, the step of performing anchorage between each of the pile top cup bearing platforms  1  and the corresponding prefabricated pier stud  2  in step 4 further includes the following steps. 
     As shown in  FIG. 6 , a pier stud metal bellow  23  is pre-embedded on an outer circumferential surface of a lower section of the prefabricated pier stud  2 , and a pier stud installation section whose outer circumferential surface is bellow-shaped is formed. In a cup mouth of each pile top cup bearing platform  1 , a cup metal bellow  24  is pre-embedded on a wall surface of a stud chamber, and a socket whose stud chamber wall surface is bellow-shaped. A central steel pad  14  with a protruding thickness of 20 mm is pre-embedded on a bottom surface of the stud chamber. The pier stud installation section is placed in the socket, an annular grouting chamber is formed between circumferential surfaces of each other, and a bottom plane grouting chamber is formed on a bottom surface. A high-strength grouting material is injected in the annular grouting chamber and the bottom plane grouting chamber to form a consolidation surface  9  to achieve the anchorage between the pile top cup bearing platform  1  and the corresponding prefabricated pier stud  2 . Both the pier stud metal bellow and the cup metal bellow adopt galvanized metal bellows. A thickness of the annular grouting chamber is 50 mm, and a thickness of the bottom plane grouting chamber is 20 mm. The high-strength grouting material is CGM-2 high-strength non-shrinkage grouting material, and a water-to-material ratio is 12% during mixing. 
     The installation method of the bent cap for mutually restraining the adjacent pier studs in the prefabricated and assembled bridge provided by the disclosure is verified in the assembly construction of the assembly-type pier studs and bent caps of the reconstruction and expansion project of the Tai&#39;an to Zaozhuang (Lu-Sujie) section of the Jingtai Expressway. The success rate of one-time assembly construction of pier studs and bent caps reaches 100%, and the construction efficiency is significantly improved. Construction difficulty of difficult construction matching and low accuracy found in assembly construction of prefabricated circular pier studs and prefabricated bent caps is effectively prevented, and a good application prospect is provided in the same type of assembly construction.