High-strength bolted connection I-shaped straight web steel beam composite beam and construction method

Abstract

The application relates to a high-strength bolt connection I-shaped straight web steel beam composite beam and a construction method, a longitudinal beam I-shaped unit is assembled on a jig frame with a temporary stable adjusting device, and is fixed to a temporary stable adjusting device of a butt joint of a cover beam section; a flat link and a main longitudinal beam are bolted to a construction support and an operation platform; a bridge surface steel bar binding type steel support placing technology, a wing plate cantilever hanging formwork pouring technology and a bridge surface concrete pouring movable operation platform are researched and developed. The application adopts an adjustable assembled jig frame structure, realizes accurate segment adjustment and positioning, improves the composite beam installation precision and the construction efficiency through an adjustable placing support and a bolted connection system, uses a material storage platform steel frame as support, installs a suspender and a channel steel underframe to complete wing plate formwork construction, improves the formwork setting efficiency, and can obtain good technical and economic benefits in practical engineering.

Description

Technical Field

[0001] This invention belongs to the field of composite beam construction, and particularly relates to a high-strength bolt-connected I-shaped straight web steel composite beam and its construction method. Background Technology

[0002] With the rapid development of my country's economy, highway engineering construction has also developed rapidly. Steel-concrete composite structures, which combine steel and concrete or steel and concrete components to form new structures, offer advantages such as steel savings, high rigidity, low cost, convenient construction, and good seismic performance. Among these, steel-concrete composite beam structures in bridges are widely used in my country. However, these structures have some significant drawbacks. For example, the connection between concrete and steel sections has not been adequately addressed, leading to slippage that severely impacts the bridge's service life. Furthermore, the processing and installation control of I-beam straight-web steel beams, as well as flange formwork, are key control points in the construction of steel-concrete composite beams. Therefore, it is necessary to conduct research on the key technical challenges related to steel-concrete composite beams.

[0003] In summary, for the construction of high-strength bolt-connected I-beam straight-web steel composite beams, it is currently very important to find a high-strength bolt-connected I-beam straight-web steel composite beam and its construction method that is fast to construct, simple to operate, and has high reliability in construction quality. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-strength bolt-connected I-shaped straight-web steel beam composite beam and its construction method.

[0005] The construction method for this type of high-strength bolt-connected I-beam straight-web steel composite beam includes the following steps:

[0006] Step 1: Set up an assembly jig with temporary stabilization and adjustment devices, support the T-shaped plate with jacks, and place the longitudinal beam I-beam unit on the top of the T-shaped plate for pre-assembly;

[0007] Step 2: Install temporary stabilizing and adjusting devices for the butt joints at the supports on the cap beam; when hoisting the longitudinal beam I-beam unit, first place it on the upper base, and then adjust the jacks to lower it onto the supports;

[0008] Step 3: The embedded unit-type operating platform is set between the longitudinal beam I-beam unit components and supported on the lower flange plate of the longitudinal beam I-beam unit components by the length of the movable struts;

[0009] Step 4: Splice and fix the longitudinal beam I-beam units together to form an I-shaped straight web steel beam;

[0010] Step five, the I-shaped straight web steel beam above the pouring of concrete mobile operation platform; bridge reinforcement cage after the bridge deck concrete pouring;

[0011] Step six, the I-shaped straight web steel beam outside fixed flange plate cantilever formwork steel support; flange plate cantilever formwork steel support through the boom and double slot steel beam connection, flange plate concrete pouring.

[0012] As preferred, in step one, the temporary stable adjustment device assembled with the jig includes steel plate, longitudinal beam I-shaped unit element, steel backing plate and jack; first set the steel plate support on the bottom, the upper part of the I-shaped steel base and steel pipe column; between the steel pipe column set scissors support, the top set the steel frame; the steel frame is provided with lug plate and screw rod, the upper part of the steel frame is provided with T-shaped plate, the T-shaped plate is provided with reserved hole for screw rod insertion, the lug plate is arranged on the side of the steel frame, the upper part of the lug plate is provided with jack, wherein the jack is placed on the bottom of the T-shaped plate, the T-shaped plate is adjusted to the designed height by adjusting the jack, and the steel backing plate is placed between the T-shaped plate and the steel frame for fixation.

[0013] As preferred, the T-shaped plate is placed on the upper part of the longitudinal beam I-shaped unit element, and pre-assembled, the longitudinal beam I-shaped unit element is provided with anti-falling baffle on both sides, wherein the anti-falling baffle is arranged on the steel frame, the anti-falling baffle is provided with adjusting screw rod, the end of the adjusting screw rod towards the longitudinal beam I-shaped unit element is provided with protective plate, and the longitudinal beam I-shaped unit element is fixed by adjusting the adjusting screw rod.

[0014] As preferred, in step two, the temporary stable adjustment device of the butt joint includes jack, sliding shaft, lower base, upper base and fixed rod; the lower base is arranged on both sides of the bent cap support, the sliding shaft is welded on the lower base, the lower bases are connected through the fixed rod, the jack is placed on the lower base, and the upper base is arranged on the upper part of the jack, wherein the upper base is inserted into the sliding shaft, the upper base moves up and down through the sliding shaft, and the height of the upper base is adjusted by adjusting the jack; when the longitudinal beam I-shaped unit element is hoisted, it is first placed on the upper base to adjust its position, the longitudinal beam I-shaped unit element falls with the upper base by adjusting the jack, and finally falls on the support.

[0015] As preferred, in step three, the embedded unit type operation platform includes adjusting screw hole, steel sleeve, threaded section, unit type steel plate and movable support rod; the unit type steel plate is welded on the square steel framework, the steel sleeve is arranged at both ends of the unit type steel plate, the movable support rod is provided with threaded section at one end and inserted into the steel sleeve, and the movable support rod is provided with adjusting screw hole; the movable support rods at both sides of the embedded unit type operation platform are in the retracted state, the length of the movable support rod is adjusted by adjusting the adjusting screw hole after being hoisted to the installation position, so that it is supported on the lower flange plate.

[0016] As preferred, in step four, the I-beam units are connected and fixed into a whole through the lower chord, upper chord, inner support rod and lower support rod.

[0017] As preferred, in step five, a square steel column is arranged on the upper part of the I-shaped straight web steel beam; an I-beam is arranged on the upper part of the square steel column; a double-spliced channel steel cross beam is arranged on the upper part of the I-beam; and a steel bar is arranged on the double-spliced channel steel cross beam; after the bridge steel bar cage is bound on the I-shaped straight web steel beam, a sliding rail is installed on the double-spliced channel steel cross beam, a concrete pouring movable operation platform is installed on the sliding rail, and a discharge port is arranged on the lower part of the concrete pouring movable operation platform for pouring concrete on the I-shaped straight web steel beam.

[0018] As preferred, in step five, a steel formwork is fixed and spliced on the flange plate cantilever formwork steel support, the flange plate cantilever formwork steel support is hoisted and bolted with the I-shaped straight web steel beam, the upper part of the hoisting rod is connected with the double-spliced channel steel cross beam, and the lower part of the hoisting rod is connected and fixed with the flange plate cantilever formwork steel support, and the formwork construction is completed and the flange plate concrete is poured.

[0019] The high-strength bolt-connected I-shaped straight web steel beam composite beam is obtained by any of the above methods.

[0020] The beneficial effects of the present application are:

[0021] 1) The present application adopts an adjustable assembly jig structure, adjusts the adjusting screw to fix the I-beam unit, and realizes accurate positioning of the segment.

[0022] 2) The present application adjusts the position of the I-beam unit on the upper base through the temporary stable adjusting device of the butt joint, and then makes it fall on the support through the adjusting jack, thereby improving the installation accuracy and construction efficiency of the composite beam.

[0023] 3) The present application connects the upper part of the hoisting rod with the double-spliced channel steel cross beam, and connects and fixes the lower part of the hoisting rod with the flange plate cantilever formwork steel support, thereby completing the flange plate formwork construction and improving the formwork setting efficiency.

[0024] 4) The present application solves the problems of construction quality control and construction efficiency of the I-shaped straight web steel beam composite beam, and has the advantages of shortening the construction period, high construction efficiency, high comprehensive cost saving ratio and the like compared with the traditional construction technology. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a longitudinal I-beam unit with temporary stable adjusting device assembly jig vertical face schematic view;

[0026] Figure 2 is a longitudinal I-beam unit with temporary stable adjusting device assembly jig longitudinal vertical face schematic view;

[0027] Figure 3 is the top plane of the assembly jig with temporary stable adjustment device;

[0028] Figure 4 is the large sample of the temporary stable adjustment device;

[0029] Figure 5 is the installation diagram of the temporary stable adjustment device;

[0030] Figure 6 is the I-shaped straight web steel beam diagram;

[0031] Figure 7 is the end of the I-shaped straight web steel beam diagram;

[0032] Figure 8 is a large sample diagram of the connecting plate (where Figure 8a is the diagram of the lower connecting plate; Figure 8b is the diagram of the upper connecting plate; Figure 8c is the diagram of the end of the lower connecting plate);

[0033] Figure 9 is the plane diagram of the I-shaped straight web steel beam;

[0034] Figure 10 is the large sample diagram of the embedded unit operation platform;

[0035] Figure 11 is the bridge deck construction section diagram.

[0036] In the figure: 1-steel plate, 2-I-beam base, 3-scissors, 4-steel frame, 5-screw, 6-resting T-shaped plate, 7-anti-falling baffle, 8-adjusting screw, 9-longitudinal beam I-beam unit, 10-protective plate, 11-steel backing plate, 12-jack, 13-ear plate, 14-steel pipe column, 15-sliding shaft, 16-lower base, 17-upper base, 18-fixing rod, 19-support, 20-capped beam, 21-pier column, 22-lower flange plate, 23-lower flange plate, 24-bolt, 25-longitudinal rib plate, 26-cross rib plate, 27-lower chord, 28-upper chord, 29-inner support rod, 30-lower support rod, 31-lower connecting plate end, 32-upper connecting plate, 33-lower connecting plate, 34-lower support rod connecting hole, 35-cross rib plate connecting hole, 36-lower chord connecting hole, 37-inner support rod connecting hole, 38-upper chord connecting hole, 39-embedded unit type operation platform, 40-adjusting screw hole, 41-steel sleeve, 42-threaded section, 43-unit type steel plate, 44-movable support rod, 45-concrete pouring movable operation platform, 46-discharge port, 47-I-beam resting longitudinal beam, 48-bridge deck reinforcement cage, 49-resting double-spliced channel steel cross beam, 50-square steel column, 51-steel formwork, 52-flange plate cantilever formwork steel support, 53-I-shaped straight web steel beam, 54-derrick. DETAILED DESCRIPTION

[0037] The application will be further described below in conjunction with examples. The following examples are only used to help understand the application. It should be pointed out that for ordinary people in the technical field, several modifications can be made to the application without departing from the principles of the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

[0038] Example 1

[0039] As an embodiment, the construction method of the high-strength bolted I-shaped straight web steel beam composite beam, the longitudinal beam I-beam unit 9 adopts a temporary stable adjusting device assembled jig, which is fixed to the temporary stable adjusting device of the butt joint of the capped beam section; a flat link and a main longitudinal beam are bolted to construct a support and an operation platform; a bridge deck reinforcement binding type steel support resting technology, a flange plate cantilever hanging formwork pouring technology, and a bridge deck concrete pouring movable operation platform 45 are developed.

[0040] Specifically includes the following steps:

[0041] Step 1, process and transport the relevant components of the high-strength bolted I-shaped straight web steel beam composite beam, construct the site of the bridge hoisting area, and prepare the corresponding mechanical equipment, personnel and construction materials;

[0042] A pre-assembly frame with a temporary stabilizing adjustment device is set up. The T-shaped plate 6 is supported by jack 12, and the longitudinal beam I-beam unit 9 is placed on the top of the T-shaped plate 6 for pre-assembly.

[0043] Step 2: Install a temporary stabilizing and adjusting device for the butt joint at the support 19 on the cap beam 20; when adjusting the T-shaped plate 6 to the design height, place a steel pad at the bottom of the T-shaped plate 6 for fixation; when hoisting the longitudinal beam I-beam unit 9, first place it on the upper base 17, then adjust the jack 12 to lower it onto the support 19; fix the longitudinal beam I-beam unit 9 by adjusting the adjusting screw 8.

[0044] Step 3: The embedded unit-type operating platform 39 is set between the longitudinal beam I-beam unit components 9. During installation, the movable support rods 44 on both sides are in a retracted state. They are hoisted to the installation position, and the length of the movable support rods 44 is adjusted by adjusting the screw holes 40 with a wrench so that they are supported on the lower flange plate 22.

[0045] Step 4: Splice and fix the longitudinal beam I-beam unit 9 together to form an I-shaped straight web steel beam 53;

[0046] Step 5: Erect a mobile concrete pouring platform 45 above the I-shaped straight web steel beam 53; After the bridge deck reinforcement cage 48 is tied, pour the bridge deck concrete.

[0047] Step 6: After the flange plate cantilever formwork steel support 52 and steel formwork 51 are spliced ​​and fixed on the ground, they are hoisted as a whole; the flange plate cantilever formwork steel support 52 is fixed on the outside of the I-shaped straight web steel beam 53; the flange plate cantilever formwork steel support 52 is connected to the double-channel steel beam 49 through the hanger 54, and the flange plate concrete is poured after the formwork is completed.

[0048] Example 2

[0049] As another embodiment, the high-strength bolted I-shaped straight-web steel beam composite beam and its construction system involved in the method of Embodiment 1, such as Figures 1 to 11 As shown.

[0050] The assembly jig with temporary stabilization and adjustment device consists of a steel plate 1, an I-beam base 2, scissor braces 3, a grid-shaped steel frame 4, screws 5, T-shaped support plates 6, anti-fall-off baffles 7, adjusting screws 8, longitudinal beam I-beam units 9, protective plates 10, steel pads 11, jacks 12, ear plates 13, and steel pipe columns 14. The assembly jig with temporary stabilization and adjustment device for longitudinal beam I-beam units 9 is set up near the steel beam hoisting area, starting with the bottom... A steel plate 1 provides support, with an I-beam base 2 bolted to the lower enlarged end of a steel pipe column 14. Scissor braces 3 are installed between the steel pipe columns 14, and a grid-shaped steel frame 4 is installed at the top. Ear plates 13 and screw rods 5 are installed on the grid-shaped steel frame 4. T-shaped plates 6 are mounted on the top of the grid-shaped steel frame 4, with pre-drilled holes for inserting screw rods 5. Jacks 12 are placed on the ear plates 13, with the jacks positioned at the bottom of the T-shaped plates 6. Longitudinal beam I-beam units 9 are pre-assembled on the top of the T-shaped plates 6. Anti-falling baffles 7 are installed on both sides of the longitudinal beam I-beam units 9, with adjusting screw rods 8 mounted on them. To protect the longitudinal beam I-beam units 9, protective plates 10 are installed at the ends of the adjusting screw rods 8 to increase their contact area. The anti-falling baffles 7 are mounted on the grid-shaped steel frame 4.

[0051] The temporary stabilizing and adjusting device for the butt joint of the longitudinal beam I-beam unit 9 on the cap beam consists of a jack 12, a sliding shaft 15, a lower base 16, an upper base 17, and a fixing rod 18. The lower base 16 is set on both sides of the support 19 of the cap beam 20. The sliding shaft 15 is welded on the lower base 16. The lower base 16 is connected in the middle by the fixing rod 18. The jack 12 is placed on the lower base 16. The upper base 17 is set on the upper part of the jack 12. The upper base 17 is inserted into the sliding shaft 15. The upper base 17 can move up and down through the sliding shaft 15. The height of the upper base 17 can be adjusted by adjusting the jack 12.

[0052] The I-beam straight web steel beam 53 is composed of longitudinal beam I-beam unit 9, lower flange plate 22, lower flange plate 23, studs 24, longitudinal rib plate 25, transverse rib plate 26, lower chord 27, upper chord 28, inner strut 29, lower strut 30, lower connecting plate end 31, upper connecting plate 32, lower connecting plate 33, lower strut connecting hole 34, transverse rib plate connecting hole 35, lower chord connecting hole 36, inner strut connecting hole 37, and upper chord connecting hole 38, etc.; the longitudinal beam I-beam unit 9 is provided with lower flange plate 22, lower flange plate 23, studs 24, longitudinal rib plate 25, and transverse rib plate 26; the longitudinal beam I-beam unit 9 is connected by lower chord 27. The upper chord 28, inner support 29, and lower support 30 are connected and fixed as a whole; the lower connecting plate end 31 is provided with a horizontal rib plate connecting hole 35 and an upper chord connecting hole 38; the upper connecting plate 32 is provided with a horizontal rib plate connecting hole 35, an inner support rod connecting hole 37, and an upper chord connecting hole 38; the lower connecting plate 33 is provided with a lower support rod connecting hole 34, a horizontal rib plate connecting hole 35, and a lower chord connecting hole 36; the horizontal rib plate 26, lower chord 27, upper chord 28, inner support 29, and lower support 30 are fixed to the lower support rod connecting hole 34, the horizontal rib plate connecting hole 35, the lower chord connecting hole 36, the inner support rod connecting hole 37, and the upper chord connecting hole 38 respectively by high-strength bolts;

[0053] The embedded unit-type operating platform 39 is composed of adjusting screw holes 40, steel sleeves 41, threaded sections 42, unit-type steel plates 43, movable support rods 44, etc.; the unit-type steel plates 43 are welded on the square steel frame, and steel sleeves 41 are set at both ends, wherein the threaded section of the movable support rod 44 is inserted into the steel sleeves 41.

[0054] The I-shaped straight web steel beam 53 is provided with square steel columns 50 on the upper part; I-beams supporting longitudinal beams 47 are provided on the upper part of the square steel columns 50; double-channel steel crossbeams 49 are provided on the upper part of the I-beams supporting longitudinal beams 47; steel bars are placed on the upper part of the double-channel steel crossbeams 49 for tying the bridge deck steel cage 48; after the bridge deck steel cage 48 is tied, a slide rail is installed on the double-channel steel crossbeams 49, and a concrete pouring mobile operating platform 45 is installed on the slide rail. A discharge port 46 is provided at the lower part of the concrete pouring mobile operating platform 45.

[0055] The flange plate cantilever hanging formwork consists of a steel template 51, a flange plate cantilever template steel bracket 52, and a hanger 54; the I-shaped straight web steel beam 53 is provided with reserved holes and is bolted to the flange plate cantilever template steel bracket 52 for fixation; the upper part of the hanger 54 is connected to the double-channel steel crossbeam 49, and the lower part is connected to the flange plate cantilever template steel bracket 52 for fixation.

[0056] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 1 can be referred to each other, and will not be repeated in this application.

[0057] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

Claims

1. A construction method for a composite beam of I-beams with straight webs connected by high-strength bolts, characterized in that, Includes the following steps: Step 1: Set up an assembly jig with temporary stabilization and adjustment devices, support the T-shaped plate with jacks, and place the longitudinal beam I-beam unit on the top of the T-shaped plate for pre-assembly; Step 2: Install temporary stabilizing and adjusting devices for the butt joints at the supports on the cap beam; when hoisting the longitudinal beam I-beam unit, first place it on the upper base, and then adjust the jacks to lower it onto the supports; Step 3: The embedded unit-type operating platform is set between the longitudinal beam I-beam unit components and supported on the lower flange plate of the longitudinal beam I-beam unit components by the length of the movable struts; Step 4: Splice and fix the longitudinal beam I-beam units together to form an I-shaped straight web steel beam; Step 5: Erect a mobile operating platform for concrete pouring above the I-shaped straight web steel beam; after the bridge deck reinforcement cage is tied, pour the bridge deck concrete. Step 6: Fix the flange plate cantilever formwork steel support to the outside of the I-shaped straight web steel beam; the flange plate cantilever formwork steel support is connected to the double-channel steel crossbeam through the hanger rod, and the flange plate concrete is poured.

2. The construction method for high-strength bolt-connected I-shaped straight-web steel beam composite beam according to claim 1, characterized in that, In step one, the assembly frame with temporary stabilizing and adjusting device includes steel plates, longitudinal beam I-beam units, steel pads, and jacks. First, a steel plate support is set at the bottom, and an I-beam base and steel pipe columns are set on top. Scissor bracing is set between the steel pipe columns, and a grid-shaped steel frame is set at the top. Ear plates and screw rods are set on the grid-shaped steel frame. T-shaped plates are installed on the upper part of the grid-shaped steel frame. The T-shaped plates have reserved holes for screw rod insertion. Ear plates are set on the side of the grid-shaped steel frame, and jacks are placed on the upper part of the ear plates. The jacks are placed at the bottom of the T-shaped plates. When the T-shaped plates are adjusted to the design height by adjusting the jacks, steel pads are placed between the T-shaped plates and the grid-shaped steel frame for fixation.

3. The construction method for high-strength bolt-connected I-shaped straight-web steel beam composite beam according to claim 2, characterized in that, The longitudinal beam I-beam unit is placed on the upper part of the T-shaped plate for pre-assembly. Anti-falling baffles are set on both sides of the longitudinal beam I-beam unit. The anti-falling baffles are set on the grid-shaped steel frame. Adjusting screws are set on the anti-falling baffles. Protective plates are set on the ends of the adjusting screws facing the longitudinal beam I-beam unit. The longitudinal beam I-beam unit is fixed by adjusting the adjusting screws.

4. The construction method for high-strength bolt-connected I-shaped straight-web steel beam composite beam according to claim 1, characterized in that, In step two, the temporary stabilizing and adjusting device for the docking joint includes a jack, a sliding shaft, a lower base, an upper base, and a fixing rod. Lower bases are set on both sides of the cap beam support, and sliding shafts are welded on the lower bases. The lower bases are connected by fixing rods. Jacks are placed on the lower bases, and upper bases are set on top of the jacks. The upper bases are inserted into the sliding shafts, and the upper bases move up and down through the sliding shafts. The height of the upper bases is adjusted by adjusting the jacks. When hoisting the longitudinal beam I-beam unit, it is first placed on the upper base and its position is adjusted. The longitudinal beam I-beam unit is lowered with the upper base by adjusting the jacks and finally lands on the support.

5. The construction method for high-strength bolt-connected I-shaped straight-web steel beam composite beam according to claim 1, characterized in that, In step three, the embedded unit-type operating platform includes adjusting screw holes, steel sleeves, threaded sections, unit-type steel plates, and movable support rods. The unit-type steel plates are welded onto the square steel frame, and steel sleeves are installed at both ends of the unit-type steel plates. One end of the movable support rod is provided with a threaded section and inserted into the steel sleeve. Adjusting screw holes are provided on the movable support rods. The movable support rods on both sides of the embedded unit-type operating platform are in a retracted state. After being hoisted to the installation position, the length of the movable support rods is adjusted by adjusting the adjusting screw holes so that they are supported on the lower flange plate.

6. The construction method for high-strength bolt-connected I-shaped straight-web steel beam composite beam according to claim 1, characterized in that, In step four, the longitudinal beam I-beam units are connected and fixed into a whole by the lower chord, upper chord, inner strut and lower strut.

7. The construction method for high-strength bolt-connected I-shaped straight-web steel beam composite beam according to claim 1, characterized in that, In step five, square steel columns are installed on the upper part of the I-shaped straight web steel beam; I-beam longitudinal beams are installed on the upper part of the square steel columns; double-channel steel crossbeams are installed on the upper part of the I-beam longitudinal beams; reinforcing bars are placed on the upper part of the double-channel steel crossbeams; after the bridge deck reinforcement cage is tied on the I-shaped straight web steel beam, a slide rail is installed on the double-channel steel crossbeam, and a concrete pouring mobile operating platform is installed on the slide rail. The lower part of the concrete pouring mobile operating platform is equipped with a discharge port for pouring concrete onto the I-shaped straight web steel beam.

8. The construction method for high-strength bolt-connected I-shaped straight-web steel beam composite beam according to claim 1, characterized in that, In step five, steel formwork is fixedly spliced ​​on the cantilever formwork steel support of the flange plate. The entire cantilever formwork steel support of the flange plate is hoisted and fixed to the I-shaped straight web steel beam with bolts. The upper part of the hanger is connected to the double-channel steel beam, and the lower part is connected to the cantilever formwork steel support of the flange plate. After the formwork is completed, the flange plate concrete is poured.

9. A composite beam of I-beams with straight webs connected by high-strength bolts, characterized in that, Obtained by the method described in any one of claims 1 to 8.

Images