Multi-storey cast-in-place concrete frame structure, the use of porous bricks, hollow bricks, aerated concrete blocks to do internal and external infill walls is more common. Because some constructors think that the infill wall is a non-load-bearing wall, there are some problems in the construction program, leaving hidden quality problems. Frame structure construction, generally the first pouring concrete frame columns, and then masonry infill walls. In order to ensure the effective connection between the frame column and the brick wall, and to improve the seismic integrity, it is necessary to set the tie reinforcement between the column and the brick wall. 1 way to set the tie reinforcement tie reinforcement set in the actual construction of the main two ways: the first is the use of pre-buried settings, the second is the use of rear-type settings. The use of pre-buried setting is a one-time buried tie reinforcement, is pre-buried in the column reinforcing bars, to be removed after the concrete molding, the tie reinforcement from the column chiseled out. Adoption of post-setting is to wait for the concrete molding and demolding, and then buried tie reinforcement. 2 Comparison of the two types of setting 2.1 Pre-embedded setting Due to the pre-embedded tie reinforcement is not firmly tied, in the column concrete vibration process is very easy to produce tie reinforcement displacement, which may lead to serious rebar slippage; a one-time embedded tie reinforcement, need to be chiseled out from the column reinforcement, the concrete column damage, not conducive to the safety of the structure; the use of the template from the drilling of pre-embedded tie reinforcement, although the solution to the control of tie reinforcement location and chiseling concrete, etc., the use of pre-embedded tie reinforcement, though the control of tie reinforcement and concrete, and the use of the template, to solve the problem. The use of pre-embedded tie bars from the template drilling, although to solve the problem of controlling the location of tie bars and chiseling concrete, but greatly increase the difficulty of demolding and damage to the template; such as the use of short bars, the welding workload is very large, and the quality of its welding is also very difficult to ensure; due to the displacement of tie bars or masonry tare bar size changes, so that the pre-embedded location of tie bars is difficult to set up in the masonry horizontal mortar joints, resulting in the phenomenon of tie bar bends and fictitious phenomena can not be very well play the role of tie, especially for large-sized masonry, the role of tie bars. Especially for the large size of the block wall may be more serious; due to design changes, the original design of the position of the wall may be canceled, and the position of the masonry may increase the wall, which will bring more difficulties to the accurate embedding of the tie reinforcement. 2.2 Adopting post-setting Post-planting tie reinforcement, on the one hand, can avoid the negative impact of chiseling on the concrete structure and the damage to the formwork due to drilling, thus bringing greater convenience to the construction of concrete structure; on the other hand, the post-planting tie reinforcement can be accurately positioned according to the changes in the building wall and masonry material size, avoiding the omission of pre-embedded tie reinforcement, off-set, wrong seams, or arbitrary bending of tie reinforcement caused by the masonry. Avoid omission of pre-buried tie reinforcement, misplacement, wrong seam or arbitrary bending of tie reinforcement during masonry, thus effectively guaranteeing the tie effect between concrete structure and masonry. From the above comparison, the setting of tie reinforcement by rear type can better meet the requirements of tie reinforcement. 3 The practical application of adopting post-setting tie reinforcement The method of post planting tie reinforcement used in the current project is, firstly, fixed by expansion bolts, secondly, welded and fixed by tie reinforcement and column reinforcement, and thirdly, post planting tie reinforcement with cementing material. 3.1 Expansion bolt fixing. Ordinary expansion bolt fixing, due to the construction of a greater impact, such as insertion depth, hole size, nut tightening, etc., its own safety performance is lower. In addition, the screw of the bolt still needs to be connected with the tie bar, often due to the length of the screw is not enough, its welding length with the tie bar does not match, some even use spot welding, can not meet the design requirements. 3.2 Tie reinforcement and column bar welding fixed. Using this method of fixing, first of all, we have to cut off the protective layer of concrete on the frame structure, and then welding, on the one hand, artificially caused by the defects of the column reinforcement, on the other hand, welding is easy to burn the column reinforcement, is not conducive to the structural safety, and the quality of the welding is often not guaranteed during the actual construction, which is not in line with the design requirements, but also in violation of the code provisions. 3.3 Cementing material fixed after planting tie reinforcement. At present, there are two methods of chemical bonding reinforcement, one is the high-performance cementing material planting technology, but the cost is high; the other is the use of cement epoxy resin adhesive, bonding fixed tie reinforcement, due to its low cost, by the contractor's welcome. 4 Frame wall tie reinforcement construction method In the frame project, wall tie reinforcement is essential, but also inseparable from the quality of the project. Its construction method is also a variety of forms, in the past often use rebar buried or buried buried iron and then welded. But the biggest problem is buried up simple, find up difficult. Usually use a large area to save chiseling way to find, not only destroy the appearance of the concrete quality, some due to chiseling depth and method is not correct, leaving the height is not allowed, directly affecting the quality of the project acceptance. I according to many years of construction site operation experience and engineering applications, for different template materials, using the following two methods, for peer reference: 4.1 template using a combination of steel formwork using the site of the edge of the rebar and flat iron made of embedded iron (length according to the thickness of the wall to determine), supporting the mold will be embedded iron welding correction, with resin glue on the surface of the paste a piece of the same size, the thickness of the requirements of than the thickness of the protective layer of 10 ~ 20mm semi-hard. 10 ~ 20mm of semi-hard or soft sponge, and then support the mold correction pouring concrete. Because of the sponge expansion and contraction, can be close to the template, to be dismantled after the template, the sponge are out of the concrete surface, clearly visible, pull off by hand, simple cleaning can be welded tie bars. 4.2 Template using shaped wooden mold or bamboo rubber mold in the production of a good embedded iron on the two holes, according to the seismic atlas or construction quality acceptance specification of the spacing of the tie bar, will be embedded iron back nailed to the template (to ensure that firm). Then support the mold correction pouring concrete. After dismantling the template, the embedded iron can be clearly identified according to the nail head, and the tie bars can be welded by simple cleaning. According to the actual construction of the situation, the above two methods to do both simple and economic, and a large number of savings in the search for buried iron labor. 5 Suggestions on the use of back-planting method of tie reinforcement In order to ensure the quality of the project, the back-planting method of tie reinforcement in the actual construction of the problems, do the following suggestions: 5.1 Ordinary expansion bolts to fix the tie reinforcement, because of its safety performance can not be effectively guaranteed, the quality of construction is difficult to control, the project should not be used. 5.2 Welding fixing of tie reinforcement and column reinforcement, because of its damage to the structure, can not guarantee the quality, should be strictly prohibited from use. 5.3 Chemical bonding fixed after planting tie reinforcement, is a current widely used method of planting reinforcement. However, the depth of the hole, the slag removal in the hole, and the protection of the finished product after planting should be ensured in the planting. In order to effectively control the quality of the project, tests should be carried out according to the requirements for the pull-out force of tie reinforcement based on different chemical bond materials, the depth of insertion of reinforcement bars of different concrete strength grades. If you can determine a quantitative standard, can be like steel, concrete and other tests, to determine the scope and number of field quality sampling, make a specific standard, more to ensure the quality of the project to meet the requirements of the design and specifications
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