On the structural column construction quality control

Abstract This paper analyzes the role of reinforced concrete structural columns and structural requirements, the quality of their construction defects elaborated and put forward concrete construction quality control measures, for your reference.

Keywords: shear strength of reinforced concrete structural columns
Setting Department of reinforced concrete structural columns to improve seismic capacity multi-storey brick house a measure, however, the current number of construction units in the construction process of concrete structural columns, pay no attention to the quality of construction so that not only can not serve to strengthen the role of seismic capacity, but also will affect the integrity of the building, bring risks to the building, so we must attach importance to the construction quality of structural columns.

1 The role of structural columns
(1 it can strengthen the connection between vertical and horizontal walls.

(2) it can increase the shear capacity of brick masonry, although the ratio does not improve much, the test showed that: the body can increase the shear capacity of brick about 10 to 30% (increase rate and the wall aspect ratio , vertical pressure stress, open hole conditions and other factors can be bound by the wall cracking, cracks on the limit of its carrying out, play a role.

(3 together with ring beam to increase the overall degree of the building, similar to the frame structure, can be called "weak framework", played a role in binding to the wall, the wall around the two-way dual-pressure state in the wall reduce the lateral deformation and improve the stability of the wall pressure to improve performance of the bearing capacity of the wall.

(2) structural columns in the construction requirements
(A multi-layer brick structural columns should be consistent: the smallest cross-section can be 240 × 180mm, should adopt the 4412 longitudinal reinforcement, stirrups spaced not more than 250mm, and in the appropriate column encryption .7 degrees lower than six, 8 degrees When more than five and nine degrees of longitudinal reinforcement should use 4414, stirrups @ ≯ 200ram, structural columns at the corners of houses may be appropriate to increase the cross-section and reinforcement.

(2 structural columns and walls should be brick horse teeth hew to connect and set up two 500mm intervals along the wall tie bar, each side wall of Nobuhito < (3 structural columns should be connected with each ring beam, set the ring beam of the housing compartment, should be no brick ring beam reinforcement with additional floors, wall corners only set structural columns, the reinforcement with the outer brick wall should be extended had an open Q: In other cases, should be reinforced with brick walls and vertical outer wall of the corresponding cross-connect. reinforcement cross-section of brick with a height of not less than four skin brick, mortar strength of not less than the M5.

(4 construction set according to structural columns, did not need a separate home-based when the base at the top has a ring beam, the structural columns can be anchored in the ring beam foundation.

3 structural column and causes of quality defects
(1 stirrup, then pull tendons lack of specification set
Walls and structural columns should be set up along the wall 50cm high the first two levels then pull steel link, stretching from the walls on each side not less than 1m, structural columns and ring beam at the intersection of the node should be properly encrypted column of the stirrups, encryption range in the ring beam, the next should not be less than one-sixth storey or 45cm, stirrups spaced not more than 10cm, the vertical structural steel columns available banding joints, the joint length lashing 1d, generally 35d, in the lashing gap segment of the stirrups should not exceed 10cm in addition to the above points can still guarantee the wall then pull bar (not entirely spacing 50cm) Others, such as encryption stirrups do almost all the most reason is the construction low level of management, technical quality is poor.

(2 axis of the dislocation of structural columns between floors
Pouring concrete in the steel skeleton is not carefully adjusted, in which the lower layer of the masonry is completed and the masonry before the pay-off, they found that the lower structural column crooked, so at this level gave to the anteroposterior, it caused, the not through the lower, please place the axis of the phenomenon.

(3) structural columns "chaos root" causes
The construction process due to structural column is a layer of masonry finish, after, to set aside the "pillar cavity" in pouring concrete.

As the "pillar cavity" through the entire layer of the masonry of time, generally the root folder with its mortar, brick slag and other debris, and because the concrete is poured into the ring Liang Yiping, finished in lifting the floor, finished masonry wall, the structural columns appear in the roots of 12mm lower than the floor of the "column pit" in "column pit" within the debris is difficult to clean, after pouring the concrete form in here, "rot" phenomenon.

(4 off of the structural column
As the structural columns within the stirrups, then pull the wall bars, ring beam reinforcement and intertwined, and steel emissions, banding without rules. Ring beams and structural columns at the same time casting process, will hinder the whereabouts of concrete in building construction are sometimes careless in the "column chamber" and the cards fell into a brick within the slag, hinder the filling of concrete, and construction of ring beam structural columns, the stone used in the river are often poor graded sand drain, if there are large stones, but also structural columns will cause "off of" phenomenon. In addition, the entire pillar once cast, if the vibrator not under attack, vibrated ill, there will be a "breaking of" place. Links to free download http://www.hi138.com (5 concrete problems
1) The concrete then rub well. Pouring concrete is not removed before touching the wood, broken bricks, floor dust and other debris, do not use water to clean, so that both before and after the concrete pour can not closely connected to the integrity of structural columns can not be guaranteed.

2) exposed tendons and Pock. Formwork before, there is no banding on the steel skeleton of concrete protective layer pads, protective layer to a thickness of less than steel resulting in the same time, some reinforcing bars are not allowed, resulting in the phenomenon of exposed tendons; concrete before pouring, templates and horse teeth have not been adequately wet rubbing brick, concrete part of the water, was a brick wall and templates to take away the concrete surface and crisp linen surface phenomenon.

3) "run pulp." Horse teeth rub one side of a brick wall on both sides of the surface is not flat, a large gap between the template and the brick wall, on the other hand, not tight patchwork template to form a "run pulp."
4) empty and "fault." Pouring concrete and some do not use plug-in vibrator, blind use of shaking and beating steel skeleton template, instead of vibrating, resulting in serious quality problems: First, concrete is generally not dense, horse teeth rub inside the concrete not in place, with brick walls and structural columns is not close, form removal, the empty and the "gap" phenomenon and the second is a general shortage of steel skeleton "fall apart" and shift.

4. To ensure quality of technology and structural columns
(1 for embedded in the wall of reinforced concrete structural columns, vertical and horizontal walls are generally the first puzzle, puzzle in the wall after the formation of "column chamber," that is reserved for the location of structural columns. Walls and structural columns with the ring beam layered masonry and cast, the sub-column section of the construction order to ensure that the center line of structural columns in the same straight line on a heavy, must be reserved for the "pillar cavity position accurately. Thus, when the masonry reinforcement should always check the structural column The vertical frame, steel frame hanging wall immediately corrected straight tie bar fixed its position and then pouring concrete in the column center line before the lead structural template or ring beam "column chamber," catchy, so that the steel skeleton Center aligned with the center column so as to ensure the correct location of structural columns.

(2 is designed to rub the horse tooth structural columns, each column foot from the start, laying back must be strictly enforced before the first principle of resistance to ensure a large cross-section for the column foot Each horse teeth rub the tooth height is about 30cm (5-layer brick high, the tooth depth is not less than 6cm. When the tooth depth of 12cm, its catchy one layer into 6cm, 12cm and then a layer into the ways in which dead horse teeth rub catchy pouring of concrete to ensure pound dense.

(3 sub-columns with steel frame should be sub-bang bar section of the construction side, lashing points to secure reliable, to avoid dislocation and slip. Vertical length of z generally take the connector 35d. Stirrups structural columns should not be less than the upper and lower ring beam 1 / 6 storeys or height of 45cm, the stirrup spacing of not more than 10cm. 500mm set at intervals along the wall for a 2 06 Rachel reinforcement requirements, must be strict with those who puzzle with the release of masonry, and to ensure release into a fixed level of ash in the dense mortar cracks.

(4 more than the mixing process with the strict implementation of requirements of coarse aggregate median diameter is appropriate to 2cm, the slump should be controlled at 5-7cm. Indwelling accordance with the provisions sub-casting the corresponding test block.

(5 sub-structure is often poured concrete columns, generally as a construction of each segment, the construction section of column height should not be greater than 2m. The bottom of each column reserved for cleaning the mouth, they clean the water before the mortar within the template column , wood, brick ballast and other debris and the new section of concrete columns before pouring on the link at the eradication of the old concrete surface to be loose gravel, and wash with water. and then mix the concrete structural columns in the configuration of the amount of salty sand-lime mortar , shop in the old concrete surface, a thickness of 1 ~ 2cm, combining old and new concrete to ensure a reliable quality.

(6 Zhu vibrator operating structure to be set up specifically responsible. Casting process for casting cylinder segments were set up to observe in order to avoid plasma leakage, excessive vibration, blocked the middle of pouring concrete in place and so on.

Proper use of structural columns, is to improve the seismic performance of masonry structures important measure, it is bound together with a ring beam brick masonry cracking, the cracks will not be further extended, even cracking still will not collapse, so that by the very brittle material composition of the structure to be significant resistance to deformation. Links to free download http://www.hi138.com