Before pouring, the formwork shall be watered and moistened, and after sundries and accumulated water are removed, the wall and column formwork shall be closed to clean the mouth.
The free fall height of concrete falling from the bucket mouth shall not exceed 2m. If it exceeds 2m, measures must be taken to increase the pipe string.
When pouring concrete with vertical structure, if the pouring height exceeds 3m, a string of tubes, conduits, chutes or holes shall be set on the side of the formwork.
When pouring concrete, it should be carried out by sections and layers, and the pouring height of each layer should be determined according to the structural characteristics and steel bar density. Generally, the layering height is 1.25 times of the length of the acting part of the plug-in vibrator, and it is not more than 500mm, and the layering thickness of the flat vibrator is 200mm.
When using plug-in vibrator, plug it in quickly and pull it out slowly. Insertion points should be evenly arranged, moved point by point, and carried out in sequence, without omission, so as to achieve uniform compaction. When vibrating the upper layer, the moving distance should not be greater than 1.5 times the action radius of the vibrator (generally 300~400mm), and it should be inserted into the lower concrete surface by 50mm to eliminate the joint between the two layers. The moving distance of the flat vibrator shall ensure the flat coverage of the vibrator for compaction.
Concrete pouring shall be carried out continuously. If there must be an interval, the interval should be as short as possible. And before the initial setting of the first layer of concrete, the second layer of concrete is poured. The longest downtime should be determined according to all cement varieties and initial setting conditions of concrete, and generally more than 2 hours should be treated as construction joints.
When pouring concrete, assign special personnel to regularly observe whether there is displacement, deformation or blockage of formwork reinforcement, reserved holes, embedded parts and steel dowel. If problems are found, stop pouring immediately, and finish finishing before the initial setting of the poured concrete.
Concrete pouring method for bottom plate
Concrete pouring is mainly transported to the basement by two concrete pumps, and the tower crane cooperates with hoisting, and commercial concrete is supplied.
The method of continuous casting by sections and layers is adopted, and the casting direction of the first, second and third sections of the second floor of the basement is advanced from 7/oA to 1/oA axis; Ⅳ, Ⅴ and Ⅴ segments are poured from 1/oA axis to D axis. The pouring direction of the foundation layer 1, 2 and 3 sections is pushed from 7/oA to 1/oA axis; The pouring direction of Ⅳ, Ⅴ and Ⅴ segments advances from 1/oA axis to U axis ... the pouring directions of the three delivery pumps respectively.
Accurately grasp the weather conditions before concrete pouring, avoid rainy days, and try to arrange the concrete pouring of the bottom plate tube at night to reduce the hydration heat inside the thick concrete. Before pouring concrete, it is necessary to set up horse stools, pedestrian walkways and operating platforms. It is forbidden to directly trample on steel bars. Whoever breaks the passage will tear it down. When pouring concrete, there should be special personnel on duty for formwork, support, reinforcement, embedment and reservation. If there is any displacement or deformation, it should be handled in time to ensure the quality of concrete.
When pouring a concrete slab with a thickness of more than 500, the method of "subsection and layering, inclined plane pouring, one slope, thin layer pouring and tamping, progressive advancement, reaching the top at one time" is adopted, as shown in the attached figure. This pouring method, in which concrete flows naturally to form a slope, avoids the frequent disassembly, washing and extension of the conveying pipe, thus improving the efficiency of pumping concrete and ensuring that the gap time between the upper and lower layers of concrete does not exceed 1.5 hours. According to the actual situation that concrete naturally forms slopes, two vibrators are arranged before and after each post-cast strip, the first one is arranged at the unloading point, which mainly solves the tamping of the upper concrete; The latter is arranged at the foot of the concrete slope to ensure the compactness of the lower concrete. With the advancement of concrete pouring, the vibrator will follow up accordingly to ensure the concrete quality of the whole height.
When pouring concrete in post-cast strip, a layer of cement mortar should be applied to the surface of construction joints. Concrete should be cut directly near the construction joints. When mechanically vibrating, it should be gradually pushed to the construction joints, and the joints of the construction joints should be compacted to make them closely combined.
When pouring mass concrete, the surface exudation is absorbed by vacuum. If excessive bleeding is found on the surface, the water cement ratio should be adjusted in time to eliminate bleeding when concrete is poured to the top.
The cement slurry on the surface of mass concrete is thick. After concrete pouring, it should be handled carefully. After about 2~4 hours, it should be leveled with a long scraper according to the elevation. Before initial setting, it shall be rolled several times with an iron roller, and then leveled and compacted with a wooden trowel, so as to close the water-collecting cracks. After about 12 hours, cover it with plastic sheets and sacks, and fully water and wet it for maintenance.
Concrete pouring of columns and walls
Before pouring columns and walls, or at the junction of newly poured concrete and lower concrete, 50mm thick cement mortar with the same proportion as concrete should be evenly poured on the bottom surface. Mortar should be put into the mold with a shovel and poured directly into the mold without a funnel.
The concrete of column wall should be cast in layers, and the thickness of each layer should be controlled at about 500mm. Concrete blanking points should be distributed and pushed in a circulating and continuous way.
When pouring the hole in the wall, the concrete height on both sides of the hole should be roughly the same. Concrete vibrating should be uniform and dense, especially for the parts with small wall thickness and dense structural steel bars and the places where the doors and windows are connected with wrong steel bars, φ 25 vibrators should be used, and φ 50 vibrators should be used for other wall beams. Considering that the concrete under the wall and window cannot be vibrated directly after sealing, the lower opening of the window can be reserved in advance, and the sealing reinforcement can be carried out after the concrete is poured to this position and vibrated tightly. When vibrating, the vibrator should be more than 300mm away from the hole edge and vibrate at the same time from both sides to prevent the hole from being deformed. The template at the lower part of the big hole should be opened and vibrated.
The constructional column concrete shall be poured in layers, and the thickness of each layer shall not exceed 300mm.
When pouring beam and slab concrete, the joint of wall and column shall be constructed according to high strength grade concrete, and the interface shall be 500 places near the wall column.
Beam slab concrete pouring
The beam and slab of ribbed floor slab should be poured at the same time, and the pouring method is "grouting method" from one end. The beam should be poured into a step shape in layers first, and then poured together with the concrete of the slab when it reaches the floor position.
The virtual paving thickness of floor slab casting should be slightly greater than the slab thickness, and the slab vibrator should be used to vibrate back and forth along the vertical casting direction. Pay attention to constantly check with moving signs or inserting rods to control the thickness of concrete slabs. After vibration, smooth the surface with a scraper or mop.
When pouring beams and slabs integrated with columns and walls, stop 1~ 1.5 hours after pouring columns and walls, so as to make them settle initially, and then continue pouring.
Construction joint setting: the floor slab shall be poured along the direction of the secondary beam, and the construction joint shall be retained within the span of the secondary beam 1/3, and the surface of the construction joint shall be perpendicular to the axis or surface of the secondary beam. The construction joint of one-way slab is left at any position parallel to the short side of slab.
Construction joints shall be fixed with wooden boards and steel wire mesh.
Construction joints shall not be continuously poured until the compressive strength of the poured concrete is not less than 1.2MPa.
Before continuing to pour concrete at the construction joint, the surface of concrete construction joint should be chiseled, the cement film and loose stones should be removed, and it should be rinsed with water. After the accumulated water is removed, first pour a layer of cement slurry or cement mortar with the same composition as the concrete, and then continue pouring concrete.
Stair concrete pouring
The concrete in the stair section is poured from bottom to top. Because the stair step adopts closed formwork, the door opening is opened on the step surface. The floor concrete is poured together with the step concrete, and it is continuously pushed upwards.
Stair concrete should be poured continuously.
Location of construction joint: according to the structural situation, it can be left in the middle of stair platform or in the range of 1/3 of stair section.
Analysis of application points of plane rules and structures
The foundation beam and stirrup are connected, and the beam is the support of the column. There is a longitudinal steel bar connection.
Stirrups are big hoops and small hoops, so repeated reinforcement is minimal. For example, two hoops of the same size can be used in earthquake and non-earthquake situations, but the reverse button cannot. The reverse buckle is only related to the outermost stirrup.
It is best to add connecting ribs to the big hoop.
The construction joint of the column is 50 to 100 at the bottom of the beam, regardless of the seismic problem, it is whole or in the middle of the column abroad. This problem must be solved.
If the foundation beam is smaller than the column, there is the problem of adding liquid beam, that is, wrapping the column. Realize the foundation beam as a support.
If the column is anchored in the foundation beam, if it is less than 500 and not less than two rectangular closed stirrups (which must be tightened), it is mainly to prevent the steel bar from deviating. The minimum bending of the column in the foundation should be greater than 150.
The densification of the overlapping area in the middle of the column is to increase the bond of concrete. Both ends of the column are for earthquake resistance, mainly strong columns and weak beams.
The plate spacing is 65438+ 0/2 based on the edge of the first rib of the foundation plate.
The foundation secondary beam is supported by the foundation main beam, and the stirrup of the secondary beam is 50 mm from the edge of the main beam.
Where the bearing column is the main beam of the foundation, the secondary beam is not connected with the column, and some secondary beams are as high as the main beam.
Matters needing attention in floor slab
The floor slab is inserted from the main reinforcement of the beam, and the lower reinforcement of the slab enters the beam for more than 5 days, but at least to the center line of the beam. The reinforcement parallel to the beam on the upper part of the plate is 1/2, and the spacing of the plate reinforcement is beam angle steel.
The reinforcement at the bottom of floor slab and non-frame beam must be compressed at the bearing.
Non-contact lap joint: the distance between two steel bars should be greater than or equal to 30+d, less than the minimum value of 0.2Ll and 150, and the distance between two circles should be greater than 0.3 ll. The bending degree of the two steel bars is 1: 12.
The negative reinforcement of the plate is reinforced at the corner of the beam.
The cantilever plate will be folded back for 5 days. It's not straight. Mainly renovation. The cantilever plate is together with the fence, and it is also 5d in the fence.
Radial reinforcement problem: the stirrup of the beam can be placed obliquely within the radial reinforcement range. So that that insertion of the radial rib can be completed.
In order to solve the problem of steel bar fighting between two cantilever plates, the relationship between steel bars is constructed in the floor.
The structure of the flat floor, sometimes the lower ribs sometimes reach the upper part. When overlapping, the overlapping place will be bent upwards, and it should be greater than 0.3 LL.
At home, the result is important, and abroad, the process is important. Reinforcement should pay attention to the process, and it is useless not to control the concrete to play particularly well in the middle. There is no result in philosophy, only process. The beginning of a process mainly depends on whether it is strong enough to start a new process. If you don't do something, you want results. Run every process well, and the results will naturally come out.
It is not advisable to pry the steel bars of beams and columns when fighting.
Problems needing attention
Let's talk about beams first, then plates, and finally columns, mainly beams. There are two equations and three unknowns in concrete structure.
There are many problems with columns, some are eccentric and some are eccentric.
The plane method considers the hierarchy, mainly that the foundation, column, beam and plate have their own subsystems. There is a connection between them. The front of foundation, column, beam and slab is a rear bearing, and the stairs are special slabs. There is a relatively complete whole, and the order of foundation, column, beam and slab is consistent with the construction.
Flat plate method, first talk about columns, then talk about beams, and then talk about plates.
The problem of light beam
How many empty nodes are constructed and how to get the maximum of several dimensions.
The steel bar at the upper part of the beam extends outside the column (inside the longitudinal steel bar of the column) and is greater than or equal to 0.4Lae. Looking at the picture, besides the text, it depends on the graphics.
The bending anchor can be bent when it is more than 0.4Lae after crossing the center line for 5 days, and whether the upper and lower ribs can be bent at the same position is not seismic. As long as the curve is greater than Lae. It is wrong that the bending anchor is still larger than Lae, and the steel bar cannot be completely broken when bending. The length of bending reinforcement is 15D, but it must be straight.
Ln is the net span length of the maximum span. Taking Ln/3 is empirical.
The lower part is anchored at the support, and the steel bar is very long. Can you pass it on? Later, the timing of repair could not be standardized. First, the beam's catch-up avoids encryption. Second, the stress is small, so it is difficult to determine whether the stress is small or not. In order to save the connection between the reinforcement and the outside of the bearing, a new article is added on page 54 of 03g101-/kloc-0. You can use a first-class mechanical connection, and you can connect anywhere you like.
The mechanical connection of columns is economical, which can save overlapping and reinforcing steel bars. Taper threads can only be used for columns, not beams.
Non-seismic connection can be made outside the support.
The atlas does not solve the problem of three rows of reinforcement, which needs to be told by the designer. If the first row is full-length, the second row is a non-full-length rib of the first row.
When there are long steel bars on the upper part of the beam, the overlapping length of vertical steel bars is 150. 150 is mainly to make at least one stirrup in the overlapping area.
Structural concept, reinforcement is divided into three grades, one is stress reinforcement, and it is also main reinforcement, and the anchorage of stress reinforcement is particularly strict. Mainly consider tension. The second is structural reinforcement: frame reinforcement and edge reinforcement, which is basically a structural requirement. You don't usually need to hook it back. A distribution bar is a vertical bar of the wall, which should be a stress bar, not a structural bar.
Reinforcement of the upper end of the top beam.
It is not necessary for the lower reinforcement of the beam to fully extend into the bearing, and the bending distance of the bearing is less than the mid-span. You can take a shortcut outside the beam support and adjust it to be greater than 0. 1Ln 1. Only two rows of steel bars in the atlas are continuously reinforced.
There are generally no two rows of ribs when adding liquid.
When the cross section of the beam is variable, it is considered as 100% anchorage. In order to lengthen the ribs, you must enter the column 50 before bending. The lower reinforcement does not enter 50 when passing through, but it can enter the column 50 at a high place.
Hanging bar, hanging bar can not put encryption bar, secondary beam can not be wrapped.
Side reinforcement: why the bigger the match, the more cracked the beam. One analysis is that there is less reinforcement. In fact, cracks are mainly caused by water-cement ratio. The second issue is stability.
Specification management program, other drawing management program.
Specification When the beam is greater than or equal to 450, it is necessary to set side bars, but the spacing should not be greater than 200.
Problems with cantilever beams:
The lower reinforcement of non-frame beam does not enter 50, because it is compressed.
The first row of ribs, one part of which is greater than 12D when bending outward, and the other part of the first row is inclined downward. Diagonal reinforcement helps stirrups resist shear. Second row of straight anchors.
Some people say that the anchor La is not safe in the column. It can be lengthened, but the code can't. This shows that La is not reliable. The probability of considering oneself is 99.97%, and the probability of failure is 0.03%. You can't improve this concept by extending it by 1 .5. Lengthening is ok, and it is bigger than the number itself. If you are not satisfied with the node in the specification, you can change it. If you change your responsibility, you will be responsible. If the responsibility is not changed, who will be responsible? This is a gray area. But personal responsibility can be reduced.
Nodes of beams and columns
Center column: Non-shearing cannot overlap, so several indexes should be large.
The optimal overlap position is in the column,
If it is the main connection, it can be in the encrypted area, but not in the support area.
Welding is unreliable. Electroslag pressure welding can only be used for columns, not beams.
When the number of steel bars in upper and lower columns is different, steel dowel shall be added. Must be 1.2Lae.
Node at the top of the column:
Outward or inward is 12D.
Columns should be supported by beams, and a complete reinforcement cage should be formed.
If the beam is particularly high, just Lae is enough, which is actually wrong. It must be complete, and the column gets to the top of the beam. There are two wrong ways: one is that the straight anchor is enough, and the other is that the bend 12d is enough.
A pillar that rises from a cross beam, which is the support of the pillar.
The straight part of the beam top must be greater than 0.5Lae, sometimes it should not be limited.
The end column should be treated strictly, and the center column should be loose. Stigma is particularly complicated.
Problems in the implementation of norms:
There are two kinds of joints, one is column to beam anchorage, A, B and C, and the other is beam to column anchorage. When the beam is too high, the reinforcement in the column is1.5AE without bending or beam top, which is not less than 65% of the reinforcement outside the column. 35% extends to the inner edge of the column and bends downward. It is difficult to count the roots.
Secondly, if the beam is particularly high, the steel bars in the beam can't reach the bottom of the beam. In my opinion, it doesn't matter whether it is 1.5 or 1.7, just follow two principles. First, in any case, the reinforcement of the column must reach the top of the beam, bending 12D, but it must be greater than1.5lae. There are three levels of earthquake resistance, which are not bad in small earthquakes, repairable in medium earthquakes and unable to collapse in large earthquakes. It should be magnitude 2, and there should be no moderate earthquake that can be repaired. In fact, it can't be repaired. Earthquakes are not nodes. There is also the biggest problem, the node can not be realized at all, how to insert the steel bar of the column, otherwise it will become a steel plate, and the steel bar of the beam and column will fight. In fact, there is no construction on the site, and you can't see the concrete after it is finished. One way now is to raise the column a little, 30 plus the diameter of the steel bar.
I believe that after the above introduction, everyone has a certain understanding of concrete pouring construction, the use of vibrators and the overall strategy. Welcome to Zhong Da for more information.
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