CN204059178U - A kind of prefabricated T-shaped beam - Google Patents

Abstract

The utility model relates to a kind of prefabricated T-shaped beam, belongs to bridge engineering field.This T-shaped beam is the improved form of conventional prefabricated T-shaped beam, adds bottom flange in end, thus the cross section of end is I shape.There is longitudinal prestressing duct in bottom flange, in the top board of end, also have longitudinal prestressing duct.The bridge of the assembled simple-supported thencontinuous of this prefabricated T-shaped beam can be adopted, at bottom flange stretch-draw longitudinal prestressing, top board stretch-draw hogging moment prestressing force.Pressure zone, bottom applies certain prestressing force, can avoid occurring crackle under the effect of temperature etc.; Bottom flange increases compression area, and under hogging moment effect, pressure zone compressive strain reduces, and the stretching strain of corresponding top also reduces, and can reduce the possibility of bridge floor cracking.Because end cross-sectional becomes I shape, facilitate transport and install, also facilitating by the construction of Simply supported non-uniform beam bridge.

Description

A prefabricated T-beam

technical field

The utility model relates to a prefabricated T-shaped beam, which belongs to the field of bridge engineering. the

Background technique

With the rapid development of high-grade highways in our country, higher requirements are put forward for the quality of bridges. The current status is: for small-span high-grade highway bridges, prefabricated reinforced concrete slab girders are mostly used, and for medium-span bridges, prefabricated prestressed concrete T-shaped (box) girders are used. diameter prestressed concrete continuous girder bridge, the current construction method mainly adopts balanced cantilever pouring method or assembly method. However, because the construction of cast-in-situ continuous beams is complicated, labor-intensive and time-consuming, people adopt the method of "simply supported first and then continuous construction" to combine the mass prefabrication of simply supported beams with the superior performance of continuous beams to realize mass production of beams or slabs. Precast production as a way to speed up the construction of continuous beams. Among the commonly used prefabricated beams, T-beams have the strongest cross-section bending resistance, the highest cross-section efficiency index, and the largest economic span. Using the method of "simply supported first and then continuous construction" can form a continuous beam bridge with a large single-span span . The lower part of the conventional prefabricated T-beam is a "horseshoe", which has poor stability and is inconvenient for transportation and installation. In the continuous system, the top of the beam section in the negative moment area on the top of the pier is under tension and the bottom is under compression, while the corresponding "horseshoe" provides a small compression area, and large creep is prone to occur under high pressure stress, aggravating the negative moment area. The roof is cracked. In addition, although the bottom of the negative bending moment area is a compression area, cracks often appear due to the effect of temperature. the

Utility model content

Conventional T-beam bridges have a small cross-sectional area in the lower part of the negative bending moment zone and a large compressive stress, and the creep deformation increases rapidly with the increase of operation time, which easily causes the curvature of the section in the negative bending moment zone to increase, thereby causing negative bending moment Roof cracking problem. In order to solve this technical problem, the solution adopted by the utility model is: provide a kind of prefabricated T-beam, and its prefabricated T-beam is the improved form of conventional prefabricated T-beam: at the end, the lower horseshoe of conventional T-beam is horizontally Expanding to the lower flange, so that the cross section of the end is I-shaped, there is a longitudinal prestressed channel in the lower flange, and there is also a longitudinal prestressed channel in the upper flange of the end. the

The prestressed tendons in the upper flange of the prefabricated T-beam adopt flat anchors, and corresponding tension grooves are reserved on the upper surface of the prefabricated T-beam. the

The prestressed tendons of the lower flange of the prefabricated T-beam adopt YGM type anchors. the

The upper flange of the prefabricated T-beam is left with protruding steel bars connected with the upper flange of the adjacent prefabricated T-beam in the transverse direction. the

The thickness of the lower flange of the prefabricated T-beam gradually decreases from the end to the mid-span direction, and the lower flange can enter the mid-span range in the longitudinal direction. the

The web thickness of the prefabricated T-beam changes from the one-eighth span from the end. the

The prestressed tendon of the lower flange of the prefabricated T-beam adopts flat anchors and has corresponding anchoring tooth blocks. the

The lower flange of the prefabricated T-beam has protruding steel bars connected with the lower flange of the adjacent prefabricated T-beam in the transverse direction. the

The beneficial effects of the utility model are: because the improved prefabricated T-beam end section is I-shaped, it is convenient for transportation and installation; a certain prestress is applied to the bottom of the negative bending moment area, which can avoid the appearance of the web under the action of temperature, etc. Cracks; compared with the continuous beam assembled by conventional prefabricated T-beams, the lower flange increases the compression area, the compressive strain in the compression area decreases under the action of negative bending moment, and the corresponding internal tensile strain of the bridge deck also decreases , can reduce the possibility of bridge deck cracking. the

Description of drawings

One of Fig. 1 utility model schematic diagram;

Fig. 2 is a schematic cross-sectional view of the end of the utility model;

Fig. 3 is a schematic cross-sectional view of the middle section of the utility model;

Fig. 4 is the second schematic diagram of the utility model.

Marked in the figure: 1. Upper flange, 2. Web plate, 3. Horseshoe, 4. Lower flange, 5. Longitudinal connecting rib tooth block of lower flange, 6. Negative moment tendon tension groove, 7. Lower wing Edge prestressed channel, 8. Negative moment tendon channel, 9. Upper flange transverse connecting bar, 10. Upper flange longitudinal connecting bar, 11. Web connecting bar. the

Detailed ways

The first embodiment of the utility model is a prefabricated T-beam as shown in Fig. 1 . The T-beam is an improved form of a conventional prefabricated T-beam. Within one-eighth of the span at the end of each end, a lower flange (4) with variable thickness is added, and the thickness of the lower flange (4) starts from the end gradually decreases towards the mid-span direction. Therefore, the cross-section of the end is I-shaped as shown in Figure 2, and there is a lower flange prestressed channel (7) in the lower flange (4), using fine-rolled threaded steel bars and corresponding YGM anchors. There are negative moment tendon tunnels (8) in the top plate at the end, flat anchors are used for prestressed tendons, and corresponding negative moment tendon tension grooves (6) are reserved on the upper surface of the prefabricated beams. On the upper flange, there is a protruding steel bar connected to the upper flange of the adjacent prefabricated T-beam in the transverse direction, that is, the upper flange transverse connecting rib (9). The construction method that adopts this prefabricated T-beam to assemble continuous girder bridge comprises the following steps:

Step 1. According to the design parameters such as bridge grade, span, and bridge deck width, carry out structural analysis of simply supported variable continuous bridges, calculate and determine the cross-sectional dimensions of T-beams, ordinary steel bars and longitudinal prestressed steel bars, which are partial to safety considerations, and can also be directly Calculate and analyze according to the constant section T-beam;

Step 2, prefabricating the prefabricated T-beam;

Step 3. Place temporary supports on the completed pier and platform. Corresponding to each T-shaped beam, there are two temporary supports at one end, which are symmetrically arranged under the lower flanges (4) on both sides of the web, and erect the prefabricated T beam;

Step 4: Connect the connecting steel bar of the transverse diaphragm, the horizontal connecting steel bar of the upper flange (1), connect the longitudinal connecting bar (10) of the upper flange corresponding to the position of the pier in the same joint, and connect the prestressed tendon channel at this place, install the formwork, Place the permanent support under the transverse diaphragm on the top of the pier, and place one corresponding to the center line of each T-beam web;

Step 5, pouring the connecting concrete of the central transverse diaphragm of the simply supported span;

Step 6. One-time pouring of the upper flange connection concrete and bridge deck pavement concrete within three quarters of the span length of the middle part of the simply supported span;

Step 7. Pouring the anti-collision guardrail within three-quarters of the span length in the middle of the simply supported span;

Step 8, pouring the lower flange (4) to connect the concrete, and pouring the concrete of the continuous section joint (including the pier top beam);

Step 9, apply the prestress in the upper flange of the negative bending moment section, and apply the prestress in the lower flange;

Step 10. Remove the temporary support, pour the remaining anti-collision barrier near the top of the pier, and complete other ancillary works.

The second embodiment of the present utility model is a modification to the first embodiment, and the prefabricated T-beam is shown in Fig. 4 . There is a longitudinal lower prestressed channel (7) in the lower flange (4), steel strands are used as prestressed tendons, flat anchors are used correspondingly, and corresponding anchoring tooth blocks are provided. the

The third embodiment of the present utility model is a modification of the first embodiment. The lower flange of the prefabricated T-beam enters the range of the mid-span section in the longitudinal direction, and the lower flange leaves a gap between the lower flange and the adjacent prefabricated T-beam in the transverse direction. The protruding reinforcement of the flange connection. the

Claims (9)

1. a prefabricated T-shaped beam, is characterized in that: be bottom flange by the lower water chestnut of conventional T beam in horizontal expansion in end, thus the cross section of end is I-shaped, has longitudinal prestressing duct in bottom flange, also has longitudinal prestressing duct in top flange, end.

2. a kind of prefabricated T-shaped beam as claimed in claim 1, is characterized in that: the presstressed reinforcing steel in top flange, end adopts flat anchor, and precast beam upper surface is reserved with corresponding stretch-draw groove.

3. a kind of prefabricated T-shaped beam as claimed in claim 1, is characterized in that: the presstressed reinforcing steel of prefabricated T-shaped lower flange of girder edge adopts YGM type ground tackle.

4. a kind of prefabricated T-shaped beam as claimed in claim 2, is characterized in that: top flange laterally leave be connected with contiguous prefabricated T-shaped beam top flange stretch out reinforcing bar.

5. a kind of prefabricated T-shaped beam as claimed in claim 3, is characterized in that: the thickness of bottom flange reduces gradually from end to span centre direction.

6. a kind of prefabricated T-shaped beam as claimed in claim 3, is characterized in that: prefabricated T-shaped lower flange of girder edge longitudinally can enter span centre uniform section segment limit.

7. a kind of prefabricated T-shaped beam as claimed in claim 1, is characterized in that: from this T-shaped beam from apart from the cross-location of end 1/8th, web thickness changes.

8. a kind of prefabricated T-shaped beam as claimed in claim 1, is characterized in that: the presstressed reinforcing steel of bottom flange adopts flat anchor, and has corresponding anchoring tooth block.

9. a kind of prefabricated T-shaped beam as claimed in claim 3, is characterized in that: bottom flange laterally leave be connected with contiguous prefabricated T-shaped lower flange of girder edge stretch out reinforcing bar.