KR101146825B1 - Prestressed concrete girder and method for tendon profiling to construct thereof - Google Patents

Abstract

PURPOSE: A pre-stressed concrete girder and a tendon profiling method for manufacturing the same are provided to reduce manufacturing costs by minimizing the cross-section of each tendon. CONSTITUTION: A pre-stressed concrete girder(100) comprises upper and lower flanges(120,110), a web(130), and multiple tendons(140) for pre-stressing. The tendons are arranged inside the upper and lower flanges and the web in a line. The lower flange has a specific height so that one of the tendons can be arranged.

Description

Prestressed Concrete Girder and method for tendon profiling to construct

The present invention relates to a prestressed concrete girder, the tendon is arranged in a compound curve shape including a straight section and parabolic section, the height of the lower flange is minimized, the prestressed concrete girder and the tendon profile for manufacturing the same Relates to the ring method.

In general, prestressed concrete is concrete in which the load capacity is raised by artificially determining the distribution and magnitude of the stress in advance so that the stress generated by the external force can be canceled to a predetermined limit. As described above, the stress applied to concrete in advance in order to offset the tensile stress generated in the lower part of the bridge by external force is called prestress, and the work of giving prestress to concrete is called prestressing. Such prestressing is provided for girders used to construct bridges. One type of girders provided with prestressing is a type I girder, which is called a PSC type I girder for short.

The conventional PSC type I girder 10 is, for example, when five tendons 14 are arranged, as shown in FIGS. 1A to 1C, the lower flange 11, the abdomen 12, and the upper flange 13. And Denden 14 was included. Here, the girder 10 is viewed from the front in the a direction, as shown in FIG. 1A, the tendons 14 are arranged in a row in the abdomen 12, and as in FIG. 1C, the tendons 10 are tendon at the center of the girder 10, which is the BB section. (14) is roughly " shape " shaped with one row and one column, and is arranged inclined to the lower flange 11. This is one example of various methods of arranging the tendons 14 in the girder 10. Both ends of the tendons 14 are arranged at equal intervals in one row, but the center is arranged in a combination of one row and one row. To this end, the lower flange 11 has a predetermined height t1, and the inclined surface S having a predetermined angle and height to be connected to the abdomen 12 is also formed to have a predetermined height t2. Further, when the girder 10 is viewed from the front in the a direction, the end portion of the tendon 14 is fixed by a separate fixing device (not shown) to maintain the tension of the tendon 14.

Looking at the arrangement and position of the tendon 14, as shown in Fig. 1d when viewed from the side of the girder 10 in the b direction, the shape of each tendon 14 was one single parabolic. Here, one single parabola refers to a parabolic shape that slowly descends with a constant curvature from one end to the center when viewed from the side and reaches a low point. At this time, it seems that there is a straight section at the central portion where the tendons 14 overlap, but this is strictly a parabola as an optical illusion. In addition, as shown in FIG. 1E, when the girder 10 is viewed in the c direction, that is, in a plane, the first, second and third tendons 14 are linear, and the fourth and fifth tendons 14d and 14e are parametrically symmetrical to each other. It was. The fourth and fifth tendons 14d and 14e appear to have straight sections at both ends visually, but this is an optical illusion that is strictly a parabolic curve.

However, the shape of the conventional tendon 14 tends to be such that the spacing between the sheath pipes is greater than the design allowance while eliminating the interference between the longitudinal reinforcing bars 15 and the tendon 14 installed while manufacturing the girder 10. It was very difficult to install. In addition, the shape of the side and plane of the tendon 14 does not deviate significantly from the parabola, but in order to determine the tendon 14 by hand, the height t2 of the inclined surface S and the height t1 of the lower flange 11 are determined. ) To be formed high, the mechanical efficiency of the girder 10, as well as the manufacturing cost was increased.

Therefore, the present invention has been made to solve the above problems, by arranging the tendon has a compound curve having a parabolic and a straight line on the side and plane, the height of the lower flange is minimized, thereby maximizing the mechanical efficiency The purpose is to provide a rest concrete girder and tendon profiling method for manufacturing the same.

In addition, the prestressed concrete girder and its fabric for reducing the manufacturing cost of the girder by minimizing the cross-sectional area of the tendon by minimizing the angular variation in the longitudinal direction with respect to the composite curve of the tendon on the side to minimize Another purpose is to provide a tendon profiling method.

In addition, to provide a prestressed concrete girder and a tendon profiling method for manufacturing the same to ensure the safety while significantly lowering the risk of girder damage by matching the harmonization curve (Cc) of the girder to the load and the average center line of tendons There is another purpose.

The present invention for achieving the above object, in the prestressed concrete girder comprising a top flange, a bottom flange, the abdomen, and a plurality of tendons arranged for prestressing, the tendons are arranged in a row in the abdomen at the end of the girder It is arranged in a row on the lower flange in the center of the girder, the average center line of the entire tendon is arranged to match the harmonic curve (Cc) for the load of the girder.

The tendon is a compound curve having a straight line and a parabola on the side, and is composed of both sides formed by a parabolic SA section and a central part formed by a straight SL section.

A tendon is a complex curve having a straight line and a parabola on a plane, and is composed of both sides formed by a straight line FL, and a central part formed by a parabola FA.

Here, the length of the straight line SL section varies depending on the angular change amount of each tendon.

The angular change of tendon is calculated by integrating the absolute value of the tendon of the tendon with respect to the longitudinal direction of the tendon.

Parabolic FA is a straight line (FL) section, a parabola (FA1) section which extends to both sides from the straight line (FL) section toward the center, and the parabolic section (FA1) section that opens. It consists of a straight line and a double parabola section of parabolic FA2 which inverts from.

In the section from the end of the girder to the center, the spacing between the highest tendon and the next tendon is greater than the respective spacing between the subtend tendons on the side.

The highest tendon of the tendons is arranged to adjust the mean center line of the whole tendons on the side to match the harmonic curve Cc for the load.

In the case of an odd number of tendons, on a plane, the highest tendon of the tendons is arranged to coincide with the longitudinal center line of the girder, and the next higher sub-tendon tendons are disposed to be divided into two mutually on both sides about the longitudinal center line of the girder.

If the tendons are even, on the plane, the tendons are divided in two on both sides about the longitudinal centerline of the girder.

On the other hand, a tendon profiling method for manufacturing a prestressed concrete girder according to the present invention, the first step (S10) of setting the height (T2) of the inclined surface (S); A second step S20 of setting an initial value of the lower flange height T1; Calculating a profile of the highest tendon among the tendons (S30); A fourth step (S40) of calculating a profile of a tendon 140 of a next lower level or higher after calculating a space between the sheath pipe and the longitudinal reinforcing bar 150 and a clearance between the sheath pipes and the allowable design space between the sheath pipes; A fifth step S50 of calculating a profile of the highest tendon so that the average center line of tendons matches the harmonic curve Cc of the load of the girder, and changing the height T1 of the lower flange; And after determining whether the height T1 of the lower flange converges to a predetermined value as it decreases or increases, if it does not converge, the process returns to step S30 of calculating the profile of the highest tendon, and if converged, ends (S60). ;

In a third step S30, determining whether the number of tendons is an odd number (S31); Calculating the setting of the highest tendon as a parabola on the side surface of the girder since the center line of the longitudinal direction of the girder and the arrangement position of the highest tendon coincide with each other when the number of tendons is an odd number (S32); And calculating the profile of the highest tendon so that interference with the longitudinal reinforcing bars is excluded when the number of tendons is even (S33).

In a fifth step S50, iteratively calculating the profile of the highest tendon so that the average center line of the tendons on the side coincides with the harmonic curve Cc for the load of the girder (S51); Determining whether the profiles of the highest tendon converge to a predetermined value, and if not, returning to step S40 of calculating a profile of the next higher tendon or less (S52); And if it converges, the height of the lower flange T1 is reduced so that the clearance between the sheath pipe and the longitudinal reinforcement and the design allowance between the sheath pipes is close to " 0 ", and then proceeds to step 6 (S60). Step (S53); is made to include.

In the fourth step (S40), iteratively searching for the profiles of the next higher or lower tendon 140 having a positive (+) interval between the sheath pipe and the longitudinal reinforcement and the allowance of the design allowance between the sheath pipes (S41); Determining whether the profiles exist through repetitive searching, and if not, proceeding to changing the height T1 of the lower flange 110 (S53); And calculating a profile in which the angular change in the longitudinal direction of the tendon 140 is minimum among the profiles of the tendon 140 below the next higher order (S43).

On the other hand, in another tendon profiling method for manufacturing the prestressed concrete girder 100 according to the present invention, the first step (S100) of setting the height (T2) of the inclined surface (S); A second step S200 of setting an initial value of the lower flange height T1; Calculating a profile of the highest tendon among the tendons (S300); A fourth step (S400) of calculating a profile of a tendon below the next higher order after calculating the clearance between the sheath pipe and the longitudinal reinforcement and the design allowance between the sheath pipes; A fifth step S500 of calculating a profile of the highest tendon so that the average center line of the tendons coincides with the harmonic curve Cc of the load of the girder, and changing the height T1 of the lower flange; The cross-sectional area of the tendon and the height (T1) of the lower flange are repeatedly calculated so as to be the minimum value, and it is determined whether the height of the lower flange 110 converges to a predetermined value, and if converged, proceeds to the next seventh step (S700). A sixth step S600 of returning to step S300 of calculating a profile of the highest tendon 141 if it does not converge; And a seventh step S700 of terminating when the height T2 of the inclined surface S converges to a predetermined value.

In a third step (S300), determining whether the number of tendons is odd (S310); If the number of tendons is an odd number, the arrangement of the longitudinal centerline and the topmost tendon in the planar direction of the girder coincides with each other, thereby setting and calculating the highest tendon as a parabola on the side (S320); And calculating the profile of the highest tendon so that interference with the longitudinal reinforcing bars is excluded when the number of tendons is an even number (S330).

In a fifth step (S500), the step (S510) of calculating the profile of the highest tendon so that the average center line of the tendons on the side coincides with the harmonic curve (Cc) for the load of the girder; If it is determined that the profiles of the highest tendon converge to a certain value and do not converge, returning to step S40 of calculating a profile of the next higher tendon or less (S520); And when converged, the height T1 of the lower flange is changed so that the clearance between the sheath pipe and the longitudinal reinforcement and the design clearance between the sheath pipes is close to " 0 ", and then proceeds to step 6 (S600). A step (S530); is included.

In the fourth step (S400), the step of repeatedly searching for the profile of the next higher or lower tendon having a positive (+) interval between the sheath pipe and the longitudinal reinforcement and the clearance allowance between the sheath pipe and each other; Determining whether the profiles exist through repetitive searching, and if not, proceeding to changing the height T1 of the lower flange (S530); And calculating a profile having a minimum angular change amount in the tendon longitudinal direction among the profiles of the tendon below the next higher order (S430).

delete

In the seventh step (S700), the step (S710) of changing the height (T2) of the inclined surface (S) to minimize the manufacturing cost of the girder; And if it is determined that the height T2 of the inclined surface S converges to a predetermined value, and if it does not converge, the process returns to step S200 of setting the initial value of the height T1 of the lower flange; ;

As described above, according to the present invention, by arranging the tendons in one row at the end of the girder and arranging the tendons in one row at the center of the girder, the mechanical efficiency of the girder is improved and the interference between the sheath pipe and the longitudinal reinforcing bar is eliminated. .
In addition, since the tendon profile is defined in the form of a compound curve in which a straight line and a parabola are combined, there is an effect that the spacing between the sheath pipes is arranged beyond the design allowable value.
In addition, by minimizing the angular change according to the length of the tendon, by minimizing the height of the lower flange, the mechanical efficiency of the girder is maximized, there is an effect that the manufacturing cost of the girder is reduced.

In addition, the average center line of the entire tendon coincides with the harmonic curve for the load of the girders, thereby minimizing the stress gradient in the longitudinal direction of the girders, maximizing safety, and girder that may occur if the stress variation in the longitudinal direction of the girders is excessive. There is an effect that the reduction of the mechanical efficiency of the is prevented.

1A is a perspective view of a girder in which a tendon is installed as an example of a conventional PSC type I girder.
1B and 1C are sectional views taken along line AA and BB of FIG. 1A.
1D and 1E are side and plan views showing the arrangement state of tendons seen in the b direction and the c direction in FIG. 1A.
Figure 2a is a perspective view showing a PSC type I girder according to a preferred embodiment of the present invention.
2B and 2C are sectional views taken along line CC and DD of FIG. 2A.
2D and 2E are side and plan views showing the arrangement state of tendons seen in the b direction and the c direction in FIG. 2A.
3A is a perspective view of a PSC type I girder of another embodiment of FIG. 2A.
3B and 3C are sectional views taken along lines EE and FF of FIG. 3A.
3D and 3E are side and plan views showing the arrangement of tendons seen in the b direction and the c direction in FIG. 3A.
4A and 4B are block diagrams illustrating a tendon profiling method for fabricating a girder according to the present invention.
5A and 5B are block diagrams illustrating a tendon profiling method according to another embodiment of FIG. 4.

Hereinafter, a PSC type I girder according to the present invention will be described in detail with reference to the accompanying drawings.

<Configuration>

Figure 2a is a perspective view showing a PSC type I girder according to a preferred embodiment of the present invention, Figures 2b and 2c is a cross-sectional view taken along the line CC and DD of Figure 2a, Figures 2d and 2e is a direction b in Figure 2a and The arrangement state of the tendon viewed from the c direction is a side view and a plan view.

PSC I-type girder 100 according to the present invention, according to the arrangement shape of the tendon 140, as shown in Figure 2a to 2c in the direction of the b direction tendon 140 is the abdomen 130 at both ends ) Is arranged in one row, and in the central portion, the tendons 140 are arranged in one row on the lower flange 110.

To describe by configuration, as shown in Figure 2a PSC I-girder 100 is the lower flange 110, the upper flange 120, the lower flange 110 and the abdomen 130 is installed while connecting the upper flange 120 ), A tendon 140, and an inclined surface S to which the lower flange 110 and the abdomen 130 are connected. Hereinafter, the arrangement shape of the tendon 140 and the optimized minimum height of the lower flange 110 and the inclined surface S will be described in detail.

The upper flange 120 is a portion that supports the load of the slab concrete that is cured on the top.

The lower flange 110 is a portion located on the upper surface of the pier (not shown), the height (T1) is an important factor in maximizing the efficiency of the girder 100 and reducing the manufacturing cost, it is minimized by the tendon profiling method described below. In addition, the height T2 of the inclined surface S is also changed so that the manufacturing cost of the girder 100 is minimum.

The tendons 140 are arranged in a row in the abdomen 130 when viewed in the a direction of FIG. 2A, and are made up of five from the highest tendons 141 to the lowest tendons 145. Here, five is shown as an example when the number of tendons 140 is an odd number, and the number of tendons 140 may be changed to an odd number, such as three or seven, depending on the installation environment. Therefore, the case where there are five tendons 140 will be described below, but this is only one example selected to describe when the tendons 140 are odd. Here, the top to bottom tendons 141, 142, 143, 144, and 145 are referred to in order of height when viewed from the end of the girder 100 for convenience. Of course, although located at the same line in the center of the girder 100, it will be easy to understand by referring to the reference numerals given to each tendon.
Here, the tendon 140 is composed of a compound curve having a straight line or parabola for each part on the side and the plane. This is to ensure that interference with the embedded longitudinal reinforcing bars 150 is actively excluded while manufacturing the girder 100, and that the spacing between the sheath pipes into which the tendons 140 are inserted is ensured to be larger than the design allowable value. Here, the sheath tube is a member embedded in the abdomen 130 so that the tendon 140 is inserted.

delete

To describe the arrangement of tendons, first, as shown in FIG. 2A, when the girder 100 is viewed from the front in the a direction, the tendons 140 are arranged in a row at equal intervals on the abdomen 130. At this time, the interval between each tendon 140 is not necessarily equal intervals.

As shown in FIG. 2B, the side cross-section at the CC line position of the girder 100 shows that the tendons 140 have the largest distance between the highest tendon 141 and the next higher tendon 142, and the next higher tendon 142 to the lowest tendon ( Up to 140).

In addition, as shown in the side cross-sectional view of the girder 100 in the D-D line position as shown in Figure 2c, the tendons 140 are arranged in one row on the lower flange (110). At this time, the intervals may be equal intervals or may be different intervals. Here, since the tendons 140 form a complex curve, the tendons are more likely to be different from each other.

Here, the most significant tendon 141 is a mean core line such that the average core line calculated by the combination with the next-order tendon 142, 143, 144, and 145 coincides with the concordant curve to loads (Cc) for the load of the girder 100. Arranged to adjust. Here, the harmonic curve Cc is a parabola having a shape coincident with the next higher tendon 143 at both ends of the girder 100 while being positioned between the second higher tendon 142 and the second higher tendon 143.

Thus, in order to adjust the average center line to match the harmonic curve, the distance between the highest tendon 141 and the next higher tendon 142 in the section from the end to the center of the girder 100 as viewed in the b direction is the second tendon 142, 143, 144, 145 or less. Are spaced greater than the space between each other. In addition, the interval between each of the next lower-order tendons 142, 143, 144, and 145 in the section from the end to the center of the girder 100 in the b direction is the shape of the complex curve of each tendon 140 and the interference between the girder 100 and the girder 100. Considering the degree of eccentricity, interference with the longitudinal reinforcing bars 150, etc. are arranged to gradually decrease. Here, the design allowance of the spacing of each tendon 140 is 40 mm.

On the other hand, the composite curve of the tendon 140 will be described in more detail. As shown in FIG. 2D, the composite curve of the tendon 140 viewed from the side in the b direction of the girder 100 forms a parabolic SA at both ends and a straight line SL at the center. That is, each tendon 140 has a parabolic SA section formed at both ends thereof, and is disposed in a complex curve having a straight line SL section formed at the center thereof. Here, the length of the parabolic SA section and the straight line SL section of each tendon 140 are different from each other. This difference is because the minimum length of the straight line SL in each tendon 140 is calculated differently by applying the minimization of the angular change in the longitudinal direction of the tendon 140 to each tendon 140. The reason why the length of the straight line SL section is shortened is that when the length of the straight line SL section becomes longer, the curvature of the parabolic SA section becomes larger and the friction loss of the tension force increases. Here, the angular change amount is calculated by integrating the absolute curvature of tendon 140. In addition, the smaller the angular change amount of the compound curve, the smaller the cross-sectional area of the tendon 140 giving the same tension, which is a factor to reduce the manufacturing cost of the girder 100.

In addition, the composite curve of the tendon 140 has a straight line (FL) section at both ends and a parabolic section (FA) at the center when viewed in a c-direction plane as shown in FIG. 2E. That is, each tendon 140 is arranged in a complex curve in which a straight line (FL) section is formed at both ends and a parabolic (FA) section is formed at the center portion. Here, the parabolic section FA has a parabolic section FA1 extending from both ends toward the center and a parabolic section FA2 in which the parabolic section FA1 is reversed. Therefore, the parabolic FA section, when viewed from one end to the center, is a straight line FL section, a parabolic FA1 section that opens to both sides from the straight line FL section toward the center portion, and a parabolic FA1 that opens. It consists of a straight line and a double parabola of the parabolic FA2 section inverted from the section. This double parabola has a distinct difference from a single conventional parabola. In addition, the length of the parabolic FA section and the straight line FL section of each tendon 140 are mutually different. This difference is omitted since it is described while explaining FIG. 2D. Here, since the number of tendons 140 is five, that is, the odd numbered tendons 141 are arranged to coincide with the planar longitudinal centerline of the girder 100, and the lower-order tendons 142, 143, 144, and 145 are respectively arranged in the girder 100. Planarly divided into two sides with respect to the longitudinal center line and disposed in mutually opposite positions. At this time, the second or lower tendons 142, 143, 144, and 145 are asymmetrical, and tendons may be symmetrical according to the length of the straight line FL and SL sections. Further, the length of the straight line FL section is calculated to be the minimum, and the reason is the same as in the case of FIG. 2D.

<Examples>

3A is a perspective view showing a PSC type I girder of another embodiment of FIG. 2A, FIGS. 3B and 3C are cross-sectional views taken along lines EE and FF of FIG. 3A, and FIGS. 3D and 3E are directions B and C in FIG. 3A. Side view and plan view of the deployment state of the tendon seen from.

3A to 3E, four tendons 140 are even, i.e., even numbers, the top tendons 141 to the lowest tendons 145 are arranged in one row in the abdomen 130 when viewed from the front in the a direction of FIG. 3A. Is placed. That is, in the embodiment of FIG. 2A, one tendon 144 that is next and lower is excluded, and the spacing of other tendons 141, 142, 143, and 145 is adjusted. Here, four is shown as an example when the number of tendons 1400 is even, and the number of tendons 140 may be changed to an even number, such as two or six, depending on the installation environment. In addition, the highest tendon 141 is arranged in a compound curve while biased to one side about the center line of the planar girder 100 as shown in FIGS. 3D and 3E.

<First production method>

4A and 4B are block diagrams illustrating a tendon profiling method for fabricating a girder according to the present invention.

First, the height T2 of the inclined surface S connecting the lower flange 110 and the abdomen 130 is set (S10).

Next, the initial value of the height T1 of the lower flange 110 is set (S20).

Next, the profile of the highest tendon 141 among the tendons 140 is calculated (S30). In more detail, it is determined whether the number of tendons 140 is an odd number (S31). Here, when the number of tendons 140 is an odd number, since the arrangement of the longitudinal centerline of the girders 100 and the topmost tendons 141 coincide with each other, the top tendons 141 are set as parabolas rather than complex curves on the side surfaces. To calculate (S32). In addition, if the number of tendons 140 is an even number, the profile of the highest tendon 141 is calculated (S33) so that interference with the longitudinal reinforcing bars 150 is excluded. Here, although the initial arrangement of the highest tendon 141 on the side is a parabola, the arrangement of the highest tendon 141 is adjusted so that the mean center line by the combination with the next higher tendon or lower tendons matches the harmonic curve Cc. A compound curve is formed. Of course, the arrangement on the plane of the top tendon 141 is a compound curve. In addition, the sub-higher tendons are arranged in a compound curve on the side and plane, this compound curve comprises a parabolic (FA, SA) and a straight line (FL, SL), a detailed description of the embodiment of Figures 2a and 3a As described in

Next, after calculating the spacing between the sheath pipe and the longitudinal reinforcing bar 150, and the allowable spacing for the design allowance between the sheath pipes, the profiles of the tendons below the next higher order are calculated (S40). In more detail, the spacing between the sheath pipe and the longitudinal reinforcing bar 150 and the clearance between the sheath pipes and the design allowance between the sheath pipes are repeated to search the profiles of the next lower tendons having a positive value (S41). It is determined whether there are profiles obtained through this (S42), and if not present, the process proceeds to step S53 of changing the height T1 of the lower flange 110 described below. In addition, when the profiles exist, a profile having a minimum angular change amount in the longitudinal direction of the tendon 140 among the profiles of the next higher tendons or less is calculated (S43), and the process proceeds to the next step S50. Here, the design allowance between the sheath pipes is 40 mm, and the clearance calculated by subtracting the design allowance from the space between the sheath pipes is measured to determine whether it is positive. In other words, if the distance between the sheath pipes is smaller than the design allowable value, it becomes negative (-) value, and when it is large, it becomes positive (+) value.

Next, the profile of the top tendon 141 is calculated so that the average center line of the tendons 140 on the side coincides with the harmonic curve Cc for the load of the girder 100 on the side, and the thickness of the lower flange 110 is calculated. (T1) is changed (S50). To explain in more detail, after the profile of the highest tendon 141 is repeatedly calculated (S51) so that the average center line of the tendons 140 on the side coincides with the harmonic curve Cc for the load of the girder 100, the highestmost It is determined whether the profiles of the tendon 141 converge to a predetermined value (S52). When converged, the height T1 of the lower flange 110 is changed so that the space between the sheath pipe and the longitudinal reinforcing bar 150 and the clearance between the sheath pipes and the design allowance between the sheath pipes are close to "zero" (S53). Thereafter, the process proceeds to the sixth step S60 described below. If it does not converge, the process returns to step S40 for calculating the profile of the next higher tendon or less. Here, the step S53 of changing the height T1 of the lower flange 110 is also a next step to be performed when it is determined that there is no profile obtained by searching for the profiles of the next lower tendon (S41). That is, when it is determined that there are no profiles in the step S42 of determining whether the profiles exist, the process proceeds to step S53 where the height T1 of the lower flange 110 is changed, whereby the lower flange 110 The height T1 is changed. Of course, the step (S53) of changing the height of the lower flange 110 is a natural progression after the step (S52) of determining the convergence.

Next, when the height T1 of the lower flange 110 decreases or increases, it is determined whether the convergence reaches a predetermined value (S60). If the convergence does not converge, the process returns to step S30 of calculating the profile of the highest tendon 141. Go and converge and you're done. Here, the height T1 of the converged lower flange 110 becomes the minimum value.

The first manufacturing method is a tendon profiling method for manufacturing the girder 100 to minimize the height T1 of the lower flange 110 in a state in which the height T2 of the inclined surface S is fixed in the girder 100. to be.

<Contrast>

First, the conventional girder is compared with the girder of the present invention according to the shape optimization of the tendon according to the present invention.

Conventional girders consist of one single parabola with tendons arranged in one row at the end of the girders in the abdomen and one row and one row at the center. As an example of the conventional girder manufactured to avoid the interference between the tendons and longitudinal rebars arranged in this way, the height T1 of the lower flange 11 is 453 mm, and the weight of the girder 10 is 197 tons.

When the conventional girder manufactured as described above configures the tendons according to the present invention while optimizing the shape of the tendons, the height T1 of the lower flange 110 is minimized, so that the height T1 of the lower flange 110 is 154 mm. And the girder 100 weight is reduced to 159 tons. When it is calculated as a ratio, the reduction ratio of the height (T1) of the lower flange 110 is calculated at the ratio of 1-154 / 453 = 66%, and the reduction ratio of the weight of the girder 100 is 1-159 / 197 = 19.3 It is calculated as a percentage.

Next, the girder of the present invention is arranged in one row and one row at the center of the girder, and the girder of the present invention to which the optimization of the tendon according to the present invention is applied while being arranged in one row.

The former girder is a composite curve of tendons, arranged in one row at the end of the girder and arranged in one row and one row at the center. That is, as the optimization of tendons is applied in accordance with the present invention, the tendons are arranged in a "┴" shape at the center. As an example of such an electronic girder, the height of the girder is 2.679m and the weight is 158.9tonf.

If the girder of the electrons thus produced is arranged in one row in the center according to the present invention and the tendon optimization is applied, the mold height of the girder is reduced to 2.575 m and the weight is reduced to 157.9 tons. When the ratio is calculated, the reduction ratio of the sentence is calculated at the ratio of 1-2.575 / 2.679 = 3.88%, and the reduction ratio of the weight is calculated at the ratio of 1-157.9 / 158.9 = 0.63%. This shows that placing the tendons in a single row in the middle of the girders in a "┴" shape with one row and one column results in a 4% better girder efficiency.

As such, the test against the conventional girder and the present girder is presented based on the tendon profiled by the applicant.

As described above, the tendon is a compound curve of the triple parabola and is arranged in one row at the center of the girder rather than the tendon as a single parabola and has a "┴" shape in one row and one column at the center of the girder. The mechanical efficiency of the girder can be maximized while minimizing the height.

<2nd production method>

5A and 5B are block diagrams illustrating a tendon profiling method according to another embodiment of FIG. 4.

The second production method is a tendon for minimizing the manufacturing cost of the girder 100 by minimizing the height T1 of the lower flange 110 as well as the height T2 of the inclined surface S as compared with the cross-sectional area of the tendon 140. Profiling method. Therefore, the first step (S10) to the fifth step (S50) of the first manufacturing method is overlapped, and each of these steps are referred to as the first step (S100) to the fifth step (S500) briefly only the basic and necessary steps Explain. Of course, the details for each step are the same or similar.

First, the height T2 of the inclined surface S connecting the lower flange 110 and the abdomen 130 is set (S100).

Next, the initial value of the height (T1) of the lower flange 110 is set (S200).

Next, the profile of the highest tendon 141 among the tendons 140 is calculated (S300). In more detail, it is determined whether the number of tendons 140 is an odd number (S310). Here, when the number of the tendons 140 is an odd number, since the arrangement of the center line in the longitudinal direction of the girder 100 and the top tendons 141 coincide with each other, the top tendons 141 may be set as a parabola to be calculated (S320). do. In addition, when the number of tendons 140 is an even number, the profile of the highest tendon 141 is calculated (S330) so that interference with the longitudinal reinforcing bars 150 is excluded. Here, although the initial arrangement of the highest tendon 141 is a parabola on the side, the arrangement of the highest tendon 141 is adjusted so that the average center line by the combination with the next higher tendon or lower tendons matches the harmonic curve Cc. A compound curve is formed. Of course, the arrangement on the plane of the top tendon 141 is a compound curve. In addition, subordinately lower tendons are arranged in a compound curve on the plane and the side, such a compound curve comprises a parabola (FA, SA) and a straight line (FL, SL), a detailed description of the embodiment of Figures 2a and 3a As described in

Next, after calculating the spacing between the sheath pipe and the longitudinal reinforcing bar 150 and the allowable spacing for the design allowances between the sheath pipes, the profile of the tendon below the next higher order is calculated, and the thickness T1 of the lower flange 110 is changed. (S400). In more detail, the space between the sheath pipe and the longitudinal reinforcing bar 150 and the clearance gap for the design allowance between the sheath pipes are repeatedly searched for the profiles of the second lower tendon having a positive value (S410). It is determined whether there are profiles obtained through this (S420), and if present, a profile having a minimum angular change amount in the longitudinal direction of the tendon 140 among the profiles of the next higher tendon or less is calculated (S430). It is determined whether there are profiles obtained through this (S420), and if not present, the process proceeds to step S530 of changing the height T1 of the lower flange 110 described below. In addition, if there are profiles, a profile having a minimum angular change in the longitudinal direction of the tendons 140 among the profiles of the tendons below the next higher order is calculated (S430). Here, the design allowance between the sheath pipes is 40 mm, and the clearance calculated by subtracting the design allowance from the space between the sheath pipes is positive. In other words, if the distance between the sheath pipes is smaller than the design allowable value, it becomes negative (-) value, and when it is large, it becomes positive (+) value.
Next, the profile of the top tendon 141 is calculated so that the average center line of the tendons 140 on the side coincides with the harmonic curve Cc for the load of the girder 100, and the thickness T1 of the lower flange 110 is calculated. ) Is changed (S500). In more detail, after the profile of the highest tendon 141 is repeatedly calculated (S510) such that the average center line of the tendons 140 coincides with the harmonic curve Cc for the load of the girder 100 on the side surface, It is determined whether the profiles of the tendon 141 converge to a predetermined value (S520). When converged, the height T1 of the lower flange 110 is changed so that the space between the sheath pipe and the longitudinal reinforcing bar 150 and the clearance between the sheath pipes and the design allowance between the sheath pipes are close to "zero" (S53). Thereafter, the process proceeds to the sixth step S600 described below. If it does not converge, the process returns to step S400 of calculating a profile of the next higher tendon. Here, the height T1 of the converged lower flange 110 becomes the minimum value. In addition, the cross-sectional area of the tendon 140 is also changed to be the minimum value in relation to the height T1 of the lower flange 110. Therefore, the height T1 of the lower flange 110 and the cross-sectional area of the tendon 140 are compared with each other to become the minimum value. In addition, the step (S530) of changing the height (T1) of the lower flange 110 is the next step to be performed when it is determined that the profile obtained by searching for the profiles of the next lower tendon (S410) does not exist (S420). Do. That is, when it is determined that there are no profiles in the step S420 of determining the existence of the profiles, the step S530 of changing the height T1 of the lower flange 110 is performed to the height of the lower flange 110. (T1) is changed. Here, when the height (T1) of the lower flange 110 is changed, the position of the longitudinal reinforcing bars 150 is changed according to the height (T1) of the lower flange 110, the gap between the sheath tube and the longitudinal reinforcing bars 150 This changes the spacing between the sheath pipes.
Next, the cross-sectional area of the tendon 140 and the height (T1) of the lower flange 110 are repeatedly calculated so as to be the minimum value, and it is determined whether the convergence to a predetermined value while the height of the lower flange 110 is changed (S600). If not converged, the process returns to step S300 of calculating the profile of the highest tendon 141, and if converged, the process proceeds to the next step S700.
Next, the height T2 of the inclined surface S is calculated (S700) so that the manufacturing cost of the girder 100 is minimum. More specifically, when the cross-sectional area of the tendon 140 and the height T1 of the lower flange 110 are determined, the height T2 of the inclined surface S is changed to minimize the manufacturing cost of the girder 100 (S710). Done. Subsequently, it is determined whether the height T2 of the inclined surface S converges to a predetermined value (S720), and when the convergence does not converge, the process returns to the step S200 of setting the initial value of the height T1 of the lower flange 110. When it converges, it ends. Here, the height T2 of the converged inclined surface S has a value in which the manufacturing cost of the girder 100 is minimum.

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In the second manufacturing method, the height of the lower flange and the cross-sectional area of the tendon are contrasted, and the cross-sectional area of the lower flange and the tendon is minimized, and the height of the inclined surface is also minimized, thereby minimizing the manufacturing cost of the girder. Can be reduced.

As described above, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. It is therefore to be understood that the above-described embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

100 ... girder 110 ... lower flange,
120 upper flange 130 ... abdomen,
140 ... Tendon 141 ... top Tendon,
142 The second highest tendon, 143 The second highest tendon,
144 ... lowest tendon 145 ... lowest tendon.

Claims (20)

In the prestressed concrete girder comprising the upper flange 120, the lower flange 110, the abdomen 130, and a plurality of tendons 140 arranged for prestressing,
The tendons 140 are arranged in one row on the abdomen 130 at the end of the girder 100, and are arranged in one row on the lower flange 110 at the center of the girder 100.
Prestressed concrete girder, characterized in that the average center line of the entire tendon 140 is arranged to match the harmonic curve (Cc) for the load of the girder (100). The method of claim 1,
The tendon 140 is a composite curve having a straight line and a parabola on the side surface, and a prestressed concrete girder comprising both sides formed by a parabolic SA section and a central part formed by a straight SL section. The method of claim 1,
The tendon 140 is a composite curve having a straight line and a parabola on a plane, and includes both sides formed by a straight line FL, and a central part formed by a parabola FA. The method according to claim 2 or 3,
Prestressed concrete girder, characterized in that the length of the straight line (SL) is different in length depending on the angular change of each tendon (140). The method of claim 4, wherein
The angular change amount of the tendon 140 is a prestressed concrete girder, characterized in that calculated by integrating the absolute curvature of the tendon 140 with respect to the longitudinal direction of the tendon 140. The method of claim 3,
The parabolic FA has a straight line (FL) section and a parabola (FA1) section that opens to both sides from the straight line (FL) section toward the center when looking at a section from one end to the center of the tendon 140 on a side surface. Prestressed concrete girder, characterized in that consisting of a straight line and a double parabola of the parabolic (FA2) section inverted from the parabolic (FA1) section. The method of claim 1,
In the section from the end to the center of the girder 100, the gap between the highest tendon 141 and the next higher tendon 142 is greater than the respective gap between the next lower tendon than the next tendon 140, characterized in that Concrete girder. The method of claim 1,
Prestressed concrete girder, characterized in that the highest tendon (141) of the tendons (140) is arranged on the side to adjust the average center line of the whole tendons (140) to match the harmonic curve (Cc). The method of claim 1,
When the tendons 140 are odd, in plan view, the highest tendons 141 of the tendons 140 are arranged to coincide with the longitudinal center line of the girder 100, and the lower tendons below the tendons 140 are girders. Prestressed concrete girder, characterized in that divided into two sides on both sides about the longitudinal center line of the (100). The method of claim 1,
When the tendons 140 are even, the tendons 140 are prestressed concrete girders, characterized in that divided into two sides on both sides of the longitudinal center line of the girders (100). In the tendon profiling method for manufacturing the prestressed concrete girder 100 of claim 1,
A first step S10 of setting the height T2 of the inclined surface S;
A second step S20 of setting an initial value of the height of the lower flange 110;
Calculating a profile of the highest tendon 141 among the tendons 140 (S30);
A fourth step (S40) of calculating a profile of a tendon 140 of a next lower level or higher after calculating a space between the sheath pipe and the longitudinal reinforcing bar 150 and a clearance between the sheath pipes and the allowable design space between the sheath pipes;
Computing the profile of the highest tendon 141 so that the average center line of the tendons 140 coincides with the harmonic curve Cc for the load of the girder 100, and changes the height T1 of the lower flange 110. A fifth step (S50); And
After determining whether the height T1 of the lower flange 110 converges to a predetermined value while being decreased or increased, if the convergence does not converge, the process returns to step S30 of calculating the profile of the highest tendon 141, and when the convergence ends, it ends. Tendon profiling method for manufacturing a prestressed concrete girder, characterized in that the sixth step (S60); The method of claim 11,
In the third step (S30),
Determining whether the number of the tendons 140 is an odd number (S31);
When the number of tendons 140 is an odd number, the arrangement of the topmost tendons 141 and the center line of the longitudinal direction of the girder 100 coincide with each other. S32); And
Calculating the profile of the highest tendon 141 so that interference with the longitudinal reinforcing bars 150 is excluded if the number of tendons 140 is an even number (S33); and for producing the prestressed concrete girder Tendon profiling method. The method of claim 11,
In the fifth step S50,
Repeatedly calculating the profile of the highest tendon 141 such that the average center line of the tendons 140 coincides with the harmonic curve Cc for the load of the girder 100 on the side surface (S51);
Determining whether the profiles of the most significant tendons 141 converge to a predetermined value, and if not, returning to calculating the profiles of the next higher tendons 140 (S40); And
When converged, the height T1 of the lower flange 110 is changed so that the clearance between the sheath pipe and the longitudinal reinforcing bar 150 and the allowable spacing between the sheath pipes and each other is close to " 0 &quot;. Proceeding to step S60 (S53); tendon profiling method for producing a prestressed concrete girder, characterized in that it comprises. The method of claim 13,
In the fourth step (S40),
Retrieving profiles of the next lower tendon (140) having a positive (+) interval between the sheath pipe and the longitudinal reinforcing bar (150) and the clearance allowance between the sheath pipes (S41);
Determining whether the profiles exist through repetitive searching, and if not, proceeding to changing the height T1 of the lower flange 110 (S53); And
Calculating the profile having the minimum angular change in the longitudinal direction of the tendon 140 among the profiles of the tendon 140 below the next higher order (S43); and the tendon for manufacturing the prestressed concrete girder, comprising the Profiling method. In the tendon profiling method for manufacturing the prestressed concrete girder 100 of claim 1,
A first step S100 of setting the height T2 of the inclined surface S;
A second step (S200) of setting an initial value of the height (T1) of the lower flange 110;
Calculating a profile of the highest tendon 141 among the tendons 140 (S300);
A fourth step (S400) of calculating a profile of a tendon 140 of a next higher level or less after calculating a spacing between the sheath pipe and the longitudinal reinforcing bar 150 and the allowable spacing of the design allowances between the sheath pipes;
Computing the profile of the highest tendon 141 so that the average center line of the tendons 140 coincides with the harmonic curve Cc for the load of the girder 100, and changes the height T1 of the lower flange 110. A fifth step (S500);
The cross-sectional area of the tendon 140 and the height T1 of the lower flange 110 are repeatedly calculated so as to be the minimum values, and it is determined whether the height of the lower flange 110 converges to a predetermined value. Proceeding to step S700 and returning to step S300 of calculating the profile of the highest tendon 141 if it does not converge (S600); And
A tendon profiling method for manufacturing prestressed concrete girder, comprising: a seventh step (S700) to terminate when the height (T2) of the inclined surface (S) converges to a predetermined value. 16. The method of claim 15,
In the third step (S300),
Determining whether the tendons (140) are odd (S310);
When the number of tendons 140 is an odd number, the arrangement of the topmost tendons 141 and the center line of the longitudinal direction of the girder 100 coincide with each other. S320); And
Calculating the profile of the highest tendon 141 so that the interference with the longitudinal reinforcing bars 150 is excluded if the number of tendons 140 is an even number (S330); Tendon profiling method. 16. The method of claim 15,
In the fifth step (S500),
Repeatedly calculating the profile of the highest tendon 141 such that the average center line of the tendons 140 coincides with the harmonic curve Cc for the load of the girder 100 on the side surface (S510);
If it is determined that the profiles of the highest tendon 141 converge to a predetermined value and do not converge, returning to step S40 of calculating a profile of the next higher tendon 140 (S520); And
When converged, the height T1 of the lower flange 110 is changed so that the clearance between the sheath pipe and the longitudinal reinforcing bar 150 and the allowable spacing between the sheath pipes and each other is close to " 0 &quot;. Proceeding to step S600 (S530); tendon profiling method for producing a prestressed concrete girder, characterized in that it comprises a. The method of claim 17,
In the fourth step (S400),
Retrieving the profiles of the next lower tendon (140) having a positive (+) interval between the sheath pipe and the longitudinal reinforcing bar (150) and the allowable spacing between the sheath pipes (S);
Determining whether the profiles exist through repetitive searching, and if not, proceeding to changing the height T1 of the lower flange 110 (S530); And
If present, a step of calculating a profile in which the angular change in the longitudinal direction of the tendon 140 is the minimum among the profiles of the tendon 140 below the next higher order (S430); the tendon for manufacturing the prestressed concrete girder, comprising the Profiling method. 16. The method of claim 15,
In the seventh step (S700),
Changing the height T2 of the inclined surface S such that the manufacturing cost of the girder 100 is minimized (S710); And
It is determined whether the height T2 of the inclined surface S converges to a predetermined value, and if it does not converge, the process returns to step S200 of setting the initial value of the height T1 of the lower flange 110 and ends when convergence. (S720); tendon profiling method for producing a prestressed concrete girder, characterized in that it comprises. delete

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