Multi-connected cast-in-situ prestressed concrete box girder

Abstract

The application provides a multi-connection cast-in-situ prestressed concrete box girder, and relates to the technical field of box girders. The multi-connection cast-in-situ prestressed concrete box girder comprises independent box girders. Expansion joints are arranged between the independent box girders and the next independent box girders, and the end of the independent box girder close to the expansion joint is provided with an anchor seal for sealing the tension end and the fixed end of the prestressed tendon. The independent box girder comprises a pier and abutments arranged at the two ends of the pier. The distance between the support center line and the expansion joint is L1, and the thickness of the anchor seal is L2, and the following conditions are met: L2 >= 1 / 2L1, and L2 >= 50 cm. The multi-connection cast-in-situ prestressed concrete box girder can directly adopt conventional double-end tensioning during construction. The bridge structure does not need to be adjusted, and the engineering quantity is not increased. Compared with the segmented tensioning form, the construction period is shorter, and the process cost and the machine leasing cost are lower. The prestressed steel tendon also does not need to be anchored on the top plate, the construction difficulty is not increased, and the overall structure is more reliable.

Description

Technical Field

[0001] This application relates to the field of box girder technology, and more specifically, to a multi-span cast-in-place prestressed concrete box girder. Background Technology

[0002] In the design of highway and municipal interchanges, due to the complex alignment and frequent lane changes, multi-span prestressed concrete box girder bridges are a common bridge structure. Since the effective length of prestress transmission along the steel strands is generally 70 to 80 meters, double-end tensioning is a simple construction method for conventional multi-span prestressed concrete box girders, maximizing the prestressing effect. However, in multi-span prestressed concrete box girder bridges, the completion of any span reduces the tensioning working surface of adjacent spans, making conventional double-end tensioning unsuitable for adjacent spans.

[0003] In related technologies, there are three solutions to the above problems. The first is to adjust the bridge structure by adding a single span of ordinary reinforced concrete box girder between the two spans. However, this can easily lead to an unreasonable overall bridge design, poor span-to-height ratio, and increased substructure work. The second is to keep the bridge structure unchanged, dividing one span into several construction sections, tensioning each section separately, and connecting the steel strands of each section with connectors. However, this solution only allows for unidirectional construction, resulting in a longer construction period, increased process costs, reduced turnover efficiency of supports and formwork, and increased equipment rental costs. The third is to use a special double-end tensioning method, anchoring the steel strand at the end without a working surface to the top slab. However, this can easily lead to cracking at the top slab anchorage, increasing construction difficulty. Utility Model Content

[0004] In order to at least address some of the shortcomings mentioned in the related technologies, this application provides a multi-section cast-in-place prestressed concrete box girder.

[0005] To achieve the above objectives, a multi-span cast-in-place prestressed concrete box girder includes independent box girders. An expansion joint is provided between each independent box girder and the next span of independent box girder. An anchor is provided on the end of each independent box girder near the expansion joint to seal the tensioning and fixing ends of the prestressing tendons. Each independent box girder includes piers and abutments, with the abutments located at both ends of the piers. The geometric center line of the abutments is defined as the support centerline. The distance between the support centerline and the expansion joint is L1, and the thickness of the anchor is L2, satisfying: L2 ≥ 1 / 2L1, and L2 ≥ 50 cm.

[0006] Furthermore, the width of the expansion joint is L3, which satisfies: L3≥16cm.

[0007] Furthermore, at least two piers are provided inside the independent box girder, and multiple piers are arranged side by side in the horizontal direction.

[0008] Furthermore, prestressed steel strands are installed inside the independent box girder, and the ends of the prestressed steel strands abut against the sealing anchor. Each prestressed steel strand includes at least two steel strands, and a fixing member is provided between adjacent steel strands.

[0009] Furthermore, the steel strands are positioned close to the bridge pier during their extension, and are parallel to the edge of the bridge pier. Adjacent steel strands are positioned parallel to each other near the fixing member.

[0010] Furthermore, prestressed steel strands are provided at the edges of the piers within the independent box girder. Prestressed steel strands are also provided between the two piers within the independent box girder.

[0011] Furthermore, the prestressed steel strands at the edges of the piers within the independent box girder are spaced 35cm apart. The prestressed steel strands between the two piers within the independent box girder are spaced 35cm or 65cm apart.

[0012] Furthermore, a step is provided on the surface of the sealing anchor near the expansion joint, and the steps in the adjacent independent box girders are provided accordingly.

[0013] Furthermore, tensioning members are installed between adjacent independent box girders for tensioning the steel strands. These tensioning members are internal locking jacks.

[0014] Furthermore, the construction process of the independent box girder is as follows: Reserve the end beam stirrups; bend the top slab main reinforcement upwards at a 90-degree angle along the vertical direction. Complete the tensioning of the steel strands and complete the anchoring. Place the reserved section beam skeleton reinforcement; restore the reserved end beam stirrups; restore the top slab main reinforcement. Use micro-expansion fiber reinforced concrete to complete the pouring of the independent box girder.

[0015] Through the above technical solution, the thickness of the anchorage in each independent box girder is at least 50cm. Before the anchorage is sealed, the distance between two adjacent independent box girders is the sum of the two anchorage sections and the expansion joint, which is at least 100cm. Compared with the distance of about 50cm in the prior art, this application leaves more space, which is sufficient to place the equipment for tensioning prestressed steel strands between two adjacent independent box girders. In other words, conventional double-end tensioning can be used to tension the prestressed steel strands.

[0016] This application's multi-span cast-in-place prestressed concrete box girder adjusts the thickness of the anchorage and the position of the support centerline, allowing for direct conventional double-end tensioning during construction. No adjustments to the bridge structure are required, and the workload is not increased. Compared to segmented tensioning, the construction period is shorter, and process and equipment rental costs are lower. Furthermore, the prestressed steel strands do not need to be anchored to the top slab, reducing construction difficulty and resulting in a more reliable overall structure.

[0017] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A structural schematic diagram of a multi-section cast-in-place prestressed concrete box girder provided in an embodiment of this application; Figure 2 This is a structural schematic diagram of a multi-span cast-in-place prestressed concrete box girder provided in an embodiment of this application.

[0020] icon: 100 - Independent box girder; 110 - Pier; 120 - Abutment; 130 - Anchorage; 140 - Support centerline; 200 - Expansion joint; 300 - Prestressed steel strand; 310 - Steel strand; 320 - Fixture. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] This embodiment provides a multi-span cast-in-place prestressed concrete box girder to solve the problems in related technologies, such as the inability to use conventional double-end tensioning between adjacent spans, which leads to increased workload, long construction period, high construction cost, and high construction difficulty.

[0025] Please see Figure 1 , Figure 2 A multi-span cast-in-place prestressed concrete box girder includes independent box girders 100. Expansion joints 200 are provided between each independent box girder 100 and the next independent box girder 100. An anchorage 130 is provided on the end of each independent box girder 100 near the expansion joint 200 to seal the tensioning and fixing ends of the prestressing tendons. Each independent box girder 100 includes piers 110 and abutments 120, with abutments 120 located at both ends of the piers 110. The geometric center line of the abutments 120 is designated as the support centerline 140. The distance between the support centerline 140 and the expansion joint 200 is L1, and the thickness of the anchorage 130 is L2, satisfying: L2 ≥ 1 / 2 L1, and L2 ≥ 50 cm.

[0026] Specifically, when constructing the multi-span cast-in-place prestressed concrete box girder according to this embodiment, the thickness of the anchorage 130 is at least 50cm, and the distance between the support centerline 140 and the expansion joint 200 is at least 100cm. Thus, during construction, before the anchorage 130, the distance between two adjacent independent box girders 100 is the sum of the distance between the two anchorage sections 130 and the width of the expansion joint 200, which is at least 100cm plus the width of the expansion joint 200. The larger space between adjacent sections allows for the placement of equipment for tensioning the prestressed steel strands 300 between the two independent box girders 100, enabling the conventional double-end tensioning method to be used to tension the prestressed steel strands 300 during construction.

[0027] Compared to other solutions in related technologies, this embodiment requires no adjustments to the bridge structure and does not increase the amount of substructure work. It also eliminates the need for tensioning specific sections, thus avoiding unidirectional construction and resulting in higher overall construction efficiency without extending the construction period. Furthermore, it avoids increasing process costs and equipment rental costs, while improving the turnover efficiency of supports and formwork. Moreover, this embodiment eliminates the need to anchor the prestressed steel strands 300mm to the top slab during construction, preserving the slab's strength and reducing construction difficulty. Overall, this embodiment is more rational and practical.

[0028] It should be noted that the distance between the support centerline 140 and the end of the independent box girder 100 should be considered in conjunction with the thickness of the anchorage 130 and the support dimensions of the abutment 120. In this embodiment, taking a conventional 27m wide roadbed as an example, the commonly used expansion joint supports for multi-span cast-in-place prestressed concrete box girders are shown in the table below:

[0029] Therefore, the distance between the support centerline 140 and the end of the independent box girder 100 is designed to be 100cm. Even after removing the 50cm thickness of the sealing anchor 130, the placement of the support can still be guaranteed.

[0030] Furthermore, regarding the stress analysis at the ends of the independent box girder, since the distance between the support centerline and the end of the independent box girder is typically 80cm, in this embodiment, the distance between the support centerline 140 and the end of the independent box girder 100 is 100cm. This results in a smaller calculated span for the side beams and a smaller mid-span bending moment. However, the cantilever section outside the expansion joint abutment 120 becomes longer, leading to a slightly larger bending moment at the top of the box girder at the support compared to conventional schemes. Taking a 13m wide box girder as an example, the diameter of the top slab main reinforcement is 25mm, the main reinforcement spacing is 15cm, and the main reinforcement at the cantilever is not considered. Live load is calculated using vehicle loads, and the cracks at the top of the box girder at the support are calculated. The calculation results are shown in the table below.

[0031] In this embodiment, the thickness of the anchor 130 is at least 50cm, and the thickness of the anchor 130 is at least half the distance from the support centerline 140 to the end of the independent box girder 100. That is to say, only about 50cm of the end of the independent box girder 100 is a reinforced concrete component. Therefore, by using fiber concrete with good crack resistance for pouring, the actual crack width should be less than the calculated value. In other words, this embodiment can meet the stress requirements of the end of the independent box girder 100.

[0032] In one embodiment, exemplarily, such as Figure 1 , Figure 2 As shown, the width of expansion joint 200 is L3, which satisfies: L3≥16cm. During use, bridges will experience longitudinal deformation due to factors such as temperature changes, concrete shrinkage, and creep. Setting a sufficiently wide expansion joint 200 provides adequate space for this deformation, meeting the expansion and contraction requirements caused by temperature deformation and shrinkage / creep of the bridge structure, and preventing problems such as cracking at the box girder ends and damage to supports due to restricted deformation.

[0033] In this embodiment, the thickness of the anchor 130 is at least 50cm, and the distance from the support centerline 140 to the end of the independent box girder 100 is at least 100cm. The reserved space between two adjacent sections is at least 116cm, providing sufficient operating space for placing the tensioning equipment when tensioning the prestressed steel strands 300, thereby supporting the conventional double-end tensioning process and improving construction efficiency and quality.

[0034] Expansion joint 200 with a width less than 16cm is insufficient to meet the expansion and contraction requirements of long-span bridges and is also detrimental to the arrangement of tensioning equipment and sealing. Expansion joint 200 with a width much greater than 16cm, while further improving deformation adaptability, leads to increased costs, construction difficulty, and maintenance costs. In summary, the width of expansion joint 200 in this embodiment satisfies the expansion and contraction requirements of most common bridges while also considering economy, construction feasibility, and structural safety.

[0035] In one embodiment, exemplarily, such as Figure 1 , Figure 2 As shown, at least two piers 110 are provided within the independent box girder 100, and multiple piers 110 are arranged side by side in the horizontal direction. The side-by-side arrangement of multiple piers 110 can distribute the loads borne by the box girder, such as vehicle loads, wind loads, and seismic forces, more evenly across each pier 110. This distributed load-bearing method effectively reduces the stress concentration problem of individual piers 110, enhancing the load-bearing capacity and deformation resistance of the entire bridge system.

[0036] For bridges with large spans or those carrying heavy vehicles, using multiple piers arranged side-by-side (110mm each) helps reduce the main girder span, bending moment, and shear force effects. This not only helps control beam deflection but also reduces the main girder section height and reinforcement requirements, improving economic efficiency.

[0037] In one embodiment, exemplarily, such as Figure 1 , Figure 2 As shown, the end of the prestressed steel strand 300 abuts against the anchorage 130. The prestressed steel strand 300 includes at least two steel strands 310, and a fixing member 320 is provided between adjacent steel strands 310. The prestressed steel strand 300 is composed of multiple steel strands 310. If there is no constraint between the steel strands 310 during tensioning, they are prone to displacement, entanglement, or uneven stress. The fixing member 320 can maintain the relative position stability between the steel strands 310, improving the overall stiffness and positioning accuracy of the steel strand.

[0038] When multiple steel strands 310 are tensioned as a whole, if the individual steel strands 310 are not effectively fixed together, it may cause asynchronous tensioning, uneven stress, or even slippage or breakage of individual steel strands 310. The fixing element 320 helps to ensure that each steel strand 310 is subjected to consistent stress during tensioning, thereby improving the accuracy and safety of prestressing application.

[0039] The ends of the prestressed steel strands 300 abut against the sealing anchor 130, which is the key part for the transfer of prestress to the concrete. Multiple steel strands 310 form a stable bundle structure through the fixing member 320, which facilitates the uniform clamping of the steel strands 310 by the anchor clamps and avoids anchorage failure or slippage caused by loose steel strands 310. It also helps the concrete or sealing material of the sealing anchor 130 to better encapsulate the steel strands 310, improving the density and corrosion resistance of the sealing anchor 130 area.

[0040] The fastener 320 can be any existing component or equipment that can meet the fixing requirements of the steel strand 310 in this embodiment, as long as it can meet the actual needs.

[0041] In one embodiment, exemplarily, such as Figure 1 , Figure 2 As shown, the steel strands 310 are positioned close to the pier 110 during their extension, and are parallel to the edge of the pier 110. Adjacent steel strands 310 are positioned parallel to each other near the fixing member 320. The parallel arrangement of the steel strands 310 to the edge of the pier 110 helps to distribute the prestress more evenly to the area near the pier 110. This avoids localized stress concentration caused by the steel strands 310 crossing or bending obliquely, reducing the risk of concrete cracking and improving structural safety.

[0042] The steel strands 310, arranged parallel to the edge of the pier 110, can better match the longitudinal stress trend of the bridge and form a more reasonable prestressing field. Especially in the area near the support centerline 140, they enhance the shear resistance and bending stiffness of this part, thereby improving the overall load-bearing capacity of the box girder.

[0043] In one embodiment, exemplarily, such as Figure 1 , Figure 2 As shown, prestressed steel strands 300 are installed at the edges of the piers 110 within the independent box girder 100. Prestressed steel strands 300 are also installed between the two piers 110 within the independent box girder 100. The piers 110 are key support points in the box girder structure, bearing significant bending moments and shear forces in their edge regions. The placement of prestressed steel strands 300 at the edges of the piers 110 effectively counteracts the tensile stress generated by the load in this area, preventing concrete cracking and improving the structure's crack resistance and durability.

[0044] The prestressed steel strands 300 pass through the area near pier 110, especially the top slab and web, which strengthens the mechanical connection between the main girder and pier 110. This "through-pier" or "around-pier" arrangement helps to achieve good synergistic stress distribution between the main girder and the substructure, improving the stiffness and stability of the overall structure.

[0045] The placement of prestressed steel strands 300 between the two piers 110 is primarily to resist the tensile stress in the mid-span bending moment and negative bending moment zone. Especially in continuous beam structures, where there is a significant negative bending moment above the supports, the proper arrangement of steel strands can effectively control crack development and improve the structural bearing capacity and fatigue life.

[0046] In one embodiment, exemplarily, such as Figure 1 , Figure 2 As shown, the prestressed steel strands 300 at the edge of the pier 110 within the independent box girder 100 have a spacing of 35 cm between their strands 310. The prestressed steel strands 300 between the two piers 110 within the independent box girder 100 have a spacing of either 35 cm or 65 cm between their strands 310. The edge area of ​​the pier 110 is a high-stress concentration zone, bearing significant negative bending moments and shear forces. The smaller spacing of the strands 310 allows for a denser arrangement of prestressing tendons, improving local tensile strength and effectively preventing crack propagation. It also helps enhance the cooperative load-bearing performance between the main girder and the pier 110.

[0047] The area at mid-span and between the two piers mainly bears positive bending moment, but the stress is relatively uniform. When the stress is small, using a larger spacing can reduce the number of steel strands 310, thus lowering the cost. When the stress is large or the span is long, a smaller spacing can still be used to ensure sufficient prestress reserve.

[0048] Smaller spacing is suitable for localized reinforcement areas, such as near pier 110, to ensure sufficient prestress density near the tensioning anchor points. Larger spacing is suitable for areas with gentler stress distribution, reducing steel reinforcement congestion, facilitating concrete pouring and vibration, and avoiding quality defects such as honeycomb and voids.

[0049] In one embodiment, exemplarily, such as Figure 1 , Figure 2 As shown, a step is provided on the surface of the anchor 130 near the expansion joint 200, and corresponding steps are provided in the adjacent independent box girders 100. The presence of the step increases the contact area and interlocking effect between the anchor 130 concrete and the main beam. When relative displacement occurs between two adjacent box girders, such as expansion and contraction caused by temperature changes, the step can effectively transfer part of the shear force, improving the overall stability and anti-slip capability of the anchor 130 area.

[0050] The anchoring concrete 130 is usually poured later and has a construction joint with the main beam. Setting a step can create a mechanical interlocking interface, enhance the bonding performance between the anchoring concrete 130 and the main beam structure, and prevent the anchoring concrete 130 from falling off or cracking due to shrinkage, temperature difference, or vibration.

[0051] In one embodiment, exemplarily, such as Figure 1 , Figure 2 As shown, tensioning members are installed between adjacent independent box girders 100 for tensioning the steel strands 310. The tensioning members are internal clamping jacks. In this embodiment, the distance from the support centerline 140 to the end of the box girder is 100cm, the anchorage 130 thickness is ≥50cm, and the expansion joint 200 width is ≥16cm, providing ample operating space for the tensioning equipment. The working space required for the internal clamping jack, i.e., the structural length of the tool, is approximately 80cm to 110cm. The internal clamping jack is small in size and lightweight, making it more suitable for tensioning operations in such limited spaces, thus improving construction feasibility.

[0052] The internal clamping jack can simultaneously tension both ends of the 310mm steel strand, achieving true double-end synchronous tensioning. Compared to single-end tensioning, double-end tensioning effectively reduces friction loss, improves the uniformity and accuracy of prestress application, and ensures a more rational structural stress distribution. Furthermore, the internal clamping jack is compact, easy to operate, and suitable for rapid on-site installation and disassembly. Due to its excellent self-anchoring performance, no additional anchoring device is required to complete the tensioning operation, thus simplifying the construction process and improving work efficiency.

[0053] It should be noted that in actual construction, other jacks or other equipment can be selected for the tensioning components according to the actual situation, as long as they can meet the requirements of this embodiment.

[0054] In one embodiment, the exemplary construction process of the independent box girder 100 is as follows: Reserve the end beam stirrups; bend the top slab main reinforcement upwards by 90 degrees. Complete the tensioning of the steel strands 310 and the anchorage sealing 130. Place the reserved section beam skeleton reinforcement; restore the reserved end beam stirrups; restore the top slab main reinforcement. Complete the pouring of the independent box girder 100 using micro-expansion fiber concrete.

[0055] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0056] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A multi-span cast-in-place prestressed concrete box girder, characterized in that, include: An independent box girder (100) is provided with an expansion joint (200) between the independent box girder (100) and the next independent box girder (100). An anchor (130) is provided at the end of the independent box girder (100) near the expansion joint (200) to seal the tensioning end and the fixed end of the prestressing tendon. The independent box girder (100) includes a pier (110) and an abutment (120), with the abutment (120) located at both ends of the pier (110); the geometric center line of the abutment (120) is set as the support center line (140). The distance between the support centerline (140) and the expansion joint (200) is L1, and the thickness of the sealing anchor (130) is L2, satisfying: L2≥1 / 2L1, and L2≥50cm.

2. The multi-section cast-in-place prestressed concrete box girder according to claim 1, characterized in that, The width of the expansion joint (200) is L3, which satisfies: L3≥16cm.

3. The multi-section cast-in-place prestressed concrete box girder according to claim 1, characterized in that, The independent box girder (100) is provided with at least two of the bridge piers (110), and the multiple bridge piers (110) are arranged side by side in the horizontal direction.

4. The multi-section cast-in-place prestressed concrete box girder according to claim 3, characterized in that, The independent box girder (100) is provided with prestressed steel strands (300), and the ends of the prestressed steel strands (300) abut against the sealing anchor (130); The prestressed steel strand (300) includes at least two steel strands (310), and a fastener (320) is provided between adjacent steel strands (310).

5. The multi-section cast-in-place prestressed concrete box girder according to claim 4, characterized in that, The steel strand (310) is positioned close to the pier (110) during its extension, and the steel strand (310) is positioned parallel to the edge of the pier (110); The adjacent steel strands (310) are arranged parallel to each other near the fixing member (320).

6. The multi-section cast-in-place prestressed concrete box girder according to claim 3, characterized in that, Prestressed steel strands (300) are provided at the edge of the pier (110) inside the independent box girder (100). Prestressed steel strands (300) are also provided between the two piers (110) within the independent box girder (100).

7. The multi-section cast-in-place prestressed concrete box girder according to claim 6, characterized in that, The prestressed steel strands (300) at the edge of the pier (110) within the independent box girder (100) are spaced 35cm apart. The prestressed steel strands (300) between the two piers (110) within the independent box girder (100) are spaced 35cm or 65cm apart.

8. The multi-section cast-in-place prestressed concrete box girder according to claim 1, characterized in that, The surface of the anchor (130) near the expansion joint (200) is provided with a step, and the steps in the adjacent independent box girders (100) are provided accordingly.

9. The multi-section cast-in-place prestressed concrete box girder according to claim 1, characterized in that, Tensioning members are provided between adjacent independent box girders (100) for tensioning steel strands (310). The tensioning component is configured as an internal clamping jack.

10. The multi-section cast-in-place prestressed concrete box girder according to claim 1, characterized in that, The construction process of the independent box girder (100) is as follows: Reserved end beam stirrups; top slab main reinforcement is bent upwards at 90 degrees along the vertical direction; Complete the tensioning of the steel strand (310) and complete the anchor sealing (130); Place the pre-reserved section of the crossbeam reinforcement; restore the pre-reserved end crossbeam stirrups; restore the top slab main reinforcement; The independent box girder (100) was cast using micro-expansion fiber concrete.

Images