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Reinforcement is an important part of the design of all monolithic structures, on which the long-lasting and reliable future of the structure depends. The process involves creating a frame from metal rods. It is placed in formwork and filled with concrete. To create this frame, they resort to knitting or welding. In this case, a correctly calculated overlap for the reinforcement plays an important role in knitting. If it is insufficient, the connection will not be strong enough, and this will affect performance. Therefore, it is important to figure out what kind of overlap to make when knitting.

There are two main methods of fastening reinforcement, according to building regulations and rules (SNiP), namely clause 8.3.26 SP 52-101-2003. It states that the connection of rods can be performed using the following types of joining:

1. Joining of reinforcement bars without welding, overlapping.
   • overlapping using parts with bends at the ends (loops, legs, hooks); for smooth rods, only loops and hooks are used;
   • overlap with straight ends of reinforcing bars of periodic profile;
   • overlapped with straight ends of reinforcing bars with transverse type fixation.
2. Mechanical and welded connection.
   • when using a welding machine;
   • using a professional mechanical unit.

SNiP requirements indicate that concrete base requires the installation of at least two continuous frames made of reinforcement. They are made by fixing the rods overlapping. For private housing construction, this method is used most often. This is due to the fact that it is available and cheap. Even a beginner can start creating a frame, since you need the rods themselves and soft knitting wire. You don't need to be a welder or have expensive equipment. And in industrial production The most common method is welding.

Note! Clause 8.3.27 states that overlapping reinforcement connections without welding are used for rods whose working cross-section does not exceed 40 mm. Places with maximum load should not be overlapped by bonding or welding.

Overlapping of rods by welding is used exclusively with reinforcement grades A400C and. Only these grades are considered weldable. This also affects the cost of products, which is higher than usual. One common class is the . But merging products with them is unacceptable. As the material heats up, it becomes less durable and loses its resistance to corrosion.

In places where there is overlap of reinforcement, welding is prohibited, regardless of the class of the rods. Why? If you believe foreign sources, there is a high probability of the connection breaking if it is subjected to heavy loads. As for Russian rules, the opinion is as follows: using electric arc welding for joining is allowed if the diameter size does not exceed 25 mm.

Important! The length of the weld directly depends on the class of the reinforcing rod and its diameter. For work, electrodes with a cross section of 4 to 5 mm are used. The requirements regulated in GOSTs 14098 and 10922 state that overlaps can be made by welding with a length less than 10 diameters of the reinforcing bars used for the work.

Docking reinforcement using the knitting method

This is the easiest way to ensure reliable design from reinforcing bars. For this work, the most popular class of rods is used, namely A400 AIII. The overlapping reinforcement connection without welding is performed using a binding wire. To do this, two rods are placed next to each other and tied in several places with wire. As mentioned above, according to SNiP, there are 3 options for fixing reinforcing bars with viscous. Fixation with straight ends of a periodic profile, fixation with straight ends of the transverse type, and also using parts with bends at the ends.

It is absolutely impossible to connect reinforcement bars with an overlap. There are a number of requirements for these connections so that they do not become the weak point of the entire structure. And it’s not just about the length of the overlap, but also other points.

Important nuances and requirements for viscous connections

Although the process of connecting rods using wire is simpler than connecting them welding machine, it cannot be called simple. Like any work, the process requires strict adherence to rules and recommendations. Only then can we say that the reinforcement monolithic design done correctly. When connecting reinforcement with an overlap using the knitting method, you should pay attention to the following parameters:

• rod cover length;
• location of the connection point in the structure and its features;
• how the overlaps are located one to the other.

We mentioned that it is impossible to place an overlapping reinforcement joint in an area with the highest degree of load and stress. These areas also include the corners of the building. It turns out that you need to correctly calculate the joints. Their location should be in areas of iron concrete structure, where there is no load, or it is minimal. What to do if it is technically impossible to comply with this requirement? In this case, the size of the overlap of the rods depends on how many diameters the reinforcement has. The formula is as follows: the size of the connection is equal to 90 diameters of the rods used. For example, if Ø20 mm reinforcement is used, then the overlap size in the area with high load is 1800 mm.

However, technical standards clearly regulate the dimensions of such connections. The overlap depends not only on the diameter of the rods, but also on other criteria:

• class of fittings used for work;
• what grade of concrete is used for pouring concrete;
• what is a reinforced concrete base used for?
• degree of load applied.

Overlapping under different conditions

So what is the overlap of the reinforcement when knitting? What is the exact data? Let's start by looking at examples. The first factor on which the overlap depends is the diameter of the rods. The following pattern is observed: the larger the diameter of the reinforcement used, the greater the overlap becomes. For example, if reinforcement with a diameter of 6 mm is used, then the recommended overlap is 250 mm. This does not mean that for rods with a cross section of 10 mm it will be the same. Typically, 30-40 times the reinforcement cross-section is used.

An example of joining 25-diameter reinforcement in a beam using tying. The amount of overlap is 40d=1000 mm.

So, to simplify the task, we use a special table that shows what overlap is used for rods of different diameters.

Diameter of used fittings A400 (mm)	Number of diameters	Estimated overlap (mm)
10	30	300
12	31,6	380
16	30	480
18	32,2	580
22	30,9	680
25	30,4	760
28	30,7	860
32	30	960
36	30,3	1090
40	38	1580

With this data, everyone can do the job correctly. But there is another table that shows overlap when using compressed concrete. It depends on the class of concrete used. Moreover, the higher the class, the smaller the spacing of reinforcement joints.

	B20 (M250)	B25 (M350)	B30 (M400)	B35 (M450)
10	355	305	280	250
12	430	365	355	295
16	570	490	455	395
18	640	550	500	445
22	785	670	560	545
25	890	765	695	615
28	995	855	780	690
32	1140	975	890	790
36	1420	1220	1155	985

As for the stretched concrete zone, in contrast to the compressed zone, the overlap will be even greater. As in the previous case, as the brand of solution increases, the length decreases.

Section of A400 reinforcement used for work (mm)	Length of overlap, depending on concrete grade (mm)
	B20 (M250)	B25 (M350)	B30 (M400)	B35 (M450)
10	475	410	370	330
12	570	490	445	395
16	760	650	595	525
18	855	730	745	590
22	1045	895	895	775
25	1185	1015	930	820
28	1325	1140	1140	920
32	1515	1300	1185	1050
36	1895	1625	1485	1315

If you correctly position the overlap relative to each other and make it required length, then the foundation skeleton will receive significant increases in strength. The connections are evenly distributed throughout the structure.

According to the norms and rules (SNiP), minimum distance There should be 61 cm between connections. Bigger is better. If you do not maintain this distance, the risk that the structure will deform under heavy loads and during operation increases. It remains to follow the recommendations to create high-quality reinforcement.

The simplest and yet truly reliable connection method metal products is the overlap of the reinforcement during tying (SNiP 52–101–2003). This is a 100% guarantee of long-term operation of the foundation or other concrete structure.

Reinforcement overlap when knitting according to SNiP

The sanitary standards and regulations of 2003 indicate all currently existing types of connections for construction. We are talking about mechanical and welded butt joints, as well as non-welded overlap joints. Mechanical ones are produced using threaded or pressed couplings using special units.

Welding is carried out by welding, and overlap joints are classified as follows:

1. Straight rods mounted or welded on the overlap of transverse rods;
2. Straight profile periodic rods;
3. Rods having legs, hooks, loops (bends).

Reinforcement with a diameter of no more than 40 mm is overlapped. According to a similar document of sanitary standards (ACI 318–05), the connection of rods with a cross-section of no more than 36 mm is allowed. This limitation is due to the fact that the reinforcement with a large cross-section has not been tested for reliability. This indicates a lack of supporting data in this regard.

The reinforcement is not connected in the tension zone of the rods and the place where the load on them is concentrated. These manipulations can be performed with or without a knitting wire. In the latter case, wire is used for tying reinforcement. Experts recommend the use of pressed connections or screw couplings when working with rods with a diameter greater than 25 mm for the following reasons:

• increasing the level of safety of the structure (the volume of concrete at the joints is limited);
• reduction financial costs for reinforcement (overlaps usually require a considerable overuse of reinforcement - up to 20-25%).

The distance between overlapping reinforcing bars in the horizontal and vertical directions should be 25 mm or more. If this condition is met, it becomes possible to unhindered penetration of concrete into the “problem” areas of the frame. For reinforcing bars over 25 mm, it is better to select the recommended distance, which is similar to the cross-section of the bars. The largest distance between reinforcement bars along the width of the foundation strip is considered to be up to 8 reinforcement sections.

In cases where tying wire is used, the distance between the rods is often zero due to the height of the protrusions of the profiles. Moreover, the largest distance between the reinforcing elements will be that which is no more than 4 diameters of the reinforcing bars. The distance between butt pairs next to each other when overlapping will be at least 30 mm (less than 2 rod diameters).

Technical features of weldless joint

It is necessary to space adjacent connections apart. Moreover, in such a way as to achieve simultaneous connection in one section of up to 50% (no more) of the reinforcing elements. The design section, which we will determine in order to determine the value of the joining reinforcements, is understood as the area of ​​130% of the total overlap parameter (measured along the bars).

Here it is necessary to understand that when designing, the joints of the rods are considered as lying in the same section, provided that the centers are located exactly in the specified zone. The shortest distance between joints according to SNiP is 610 mm. According to ACI 318–05 and sanitary standards, it is recommended that untied (free) connections of rods be made in structures without prestressing.

This advice is quite logical, because the concrete mixture with such a connection will flood the rods from all sides. And this is a guarantee of ultra-reliable fixation of each rod, which cannot be achieved when pouring an incomplete circle of reinforcement and an adjacent rod tied with binding wire. In addition, the overlap in length cannot be less than 25 cm.

Another important provision of the Sannorm is that in the 1st design section the connection can have no more than 50% of steel rods in the foundation strip. In addition, it is possible to join welded mesh and individual reinforcing elements using the described option without the necessary separation. However, such an assumption will only be valid when using reinforcement for structural reinforcement.

An overlap of 30 cm or more is possible provided that the reinforcement is functioning in compression. By many foreign countries In the construction documentation, the overlap was established at a level of 40 diameters of the connecting reinforcing elements. In the CIS countries, this value is equal to 50 diameters (A400 fittings).

Also, the value of the recommended overlap depends on the grade of concrete for pouring the foundation. For example, for the M300 mixture it has 35 diameters, M250 - 40, M200 - 50. But for reinforcing bars A-II and A-I, the overlap is always selected based on 40 diameters. But it should be borne in mind that all this will be true for the indicators in the calculation. In practice, real (not minimum) overlap values ​​are usually several times larger.

Real values ​​of reinforcement overlap

The length of the overlap of the rods during anchoring is set based on the force acting in the reinforcement structure and the perception of the resistance forces of the steel elements, as well as the adhesion forces of concrete and reinforcing rods along the entire length of the connection. Sanitary standards for overlap of reinforcement when knitting recommend the following overlap lengths (all parameters in mm) overlap/section:

• 1090 / 36;
• 960 / 32;
• 860 / 28;
• 760 / 25;
• 680 / 22;
• 580 / 18;
• 480 / 16;
• 380 / 12;
• 300 / 10.

The SNiP tables also contain the length of the anchor overlap for various brands concrete mixture for reinforcement bars in compression/tension.

There are some other important points of SNiP that were discussed in this publication:

1. V mandatory in the area of ​​overlap anchoring, installation of additional transverse reinforcement is necessary;
2. preventing the anchoring of adjacent rods from being separated by at least 61 cm;
3. cross-shaped overlaps must be connected using plastic clamps or fasteners or annealed ductile wire.

According to these tables, the shortest overlap length for concrete mix M450 with a cross-section of A400 rod of 6 mm = 20 cm. But for concrete M250 and reinforcement with a cross-section of 40 mm, the length will be already 158 cm.

Good morning!

Today at Unsolicited advice I will continue the topic of working concreting joints and joining reinforcement. More precisely, we have already talked about seams, now let's talk about docking.

It is not always the case that reinforcement of the required length arrives at the construction site; as a result, the question arises that it needs to be joined. As with the issue of concreting joints, many designers try to ignore this problem and leave the decision to the builders. Anyone who does this puts the design at risk.

The builder is not required to know where to join the reinforcement. He will dock it in the most convenient place for him, but at the same time - in the most dangerous place for construction. The “Recommendations for the use of reinforcing bars according to DSTU 3760-98 in the design and manufacture of reinforced concrete structures without prestressing reinforcement” well describes the requirements (see paragraph 2.3.3), I will give a couple of especially important ones here:

1. “Lapped joints of working reinforcement are not recommended to be located in the stretched zone of bending and eccentrically stretched elements in the zone of maximum forces and places full use fittings. Overlapping joints of working reinforcement are not allowed in linear elements whose cross-section is fully stretched.” Let me explain a little. We must clearly convey to the builder where he can join the reinforcement. You cannot join in a tension zone: that is, the lower working reinforcement in a slab, for example, cannot be joined in the middle of the span, and the upper reinforcement above the supports (for multi-span slabs). It is there that the slab is stretched, this is what the moment diagram tells us, and even just an attempt to imagine how the floor will bend during the loading process: which of its surfaces will try to stretch and which will compress. It’s very easy to make a diagram like this:

I gave an example for a floor slab, but similar diagrams can be made for any structure in which the reinforcement is ordered linear meters. Sometimes the designer immediately sets the layout of rods of a certain length, indicating the joint locations. Here there is a risk of drowning in correspondence to coordinate more and more new docking points, because Builders may have reinforcement of completely unpredictable lengths. The values ​​of L/4 and L/3 are taken from a specific calculation and may differ from those given by me.

2. “Joints” welded mesh and frames, as well as stretched rods of knitted frames and lapped meshes should be spaced apart. In this case, the cross-sectional area of ​​the working rods joined in one place or at a distance less than the bypass length l l should be no more than 50% of the total cross-sectional area of ​​the tensile reinforcement.

The rods should be positioned as freely as possible, maximum distance the clearance between the joined rods should not exceed 4d or 50mm.

The clear distance between joints located in different places along the length of the element must be at least 0.5 l l, or at the axes of the joints at least 1.5 l l.

Adjacent lap joints must be spaced at a clear distance of at least 2d and at least 30mm.” How to convey all this to the builder? I advise you to take Figure 6 of the “Recommendations...” as a basis and show the following diagram on the drawing:

Please note that the amount of overlap for working reinforcement in the upper and lower zones of the slab is different (see coefficient from Table 12 of the “Recommendations...”). In the example, I gave a diagram for reinforcement with a diameter of 12 mm.

Always pay attention to the fact that in one section there should be no more than 50% of the joints of tensile reinforcement bars. Sometimes this requirement is very difficult to fulfill, especially in cramped circumstances, and it is necessary to change the diameters of the rods and their number.

In general, I advise you to study the recommendations far and wide before starting to design an overlap in a specific structure.

I also want to write about joining reinforcement in columns. This is a specific topic, the solution to which has not yet been found for me. How before, before the introduction of rolled steel according to DSTU 3760, were reinforcing bars joined according to GOST 5781? Here is a drawing from the “Reinforced Concrete Structure Design Guide”:

It is clear from the figure that half of the outlet rods extend out of the ceiling by the length of the overlap, the second half by two lengths of the overlap. This ensures the spacing of the joints - no more than 50% in one section. But the Gost reinforcement had completely different overlap lengths - several times less (!) than for reinforcement according to DSTU 3760. For example, let’s look: for a rod according to DSTU with a diameter of 20 mm in B25 concrete, the overlap value is 1630 mm (according to the calculation according to the “Recommendations” ..."). Two overlap lengths are already 3260 mm (sometimes this is less than the height of the floor!). What to do about it, the rules are silent. What do designers do about this? Either they release all the rods by the same amount of overlap (I won’t say that this is correct), or they choose the joining method by welding with overlays or the crimping method. But all these options need to be agreed upon with the customer - after all, his money and his capabilities.

Perhaps I will talk about the features of joining reinforcement in columns in the next issue. Happy designing to you!

Sincerely, Irina.

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0 #33 Irina

Overlapping reinforcement is the simplest and most reliable way to connect rods to each other. The overlap guarantees long-term operation of any concrete structure. Despite its simplicity, there are a few things you need to know before getting started. SNiP has separate paragraphs devoted to connecting reinforcement bars, so in this article we will go over the main provisions. It is also worth mentioning other methods of joining rods, which are worth familiarizing yourself with.

Types of docking

The norms and rules for connecting reinforcement bars are described in SNiP; today three types are used: welding, mechanical connections and overlap. Co welding work everything should be clear regarding mechanical options, then in this case the connection of the rods occurs using pressed or threaded couplings. We are interested in the overlap of reinforcement, so we will consider three types of this connection:

• rods with loops, claws or hooks - the easiest type for DIY work;
• fittings with straight ends by welding or installation;
• profile rods.

Overlap is used if the cross-section of the rods does not exceed 40 mm. ACI 318-05 states that the cross-section should be no more than 36 mm. This range was chosen only because there were no registered tests using larger diameters, therefore, there is no confirmation of the safety of the connection in SNiP.

Joint diagram. Shown here is the connection for strip foundation.

Basic provisions of SNiP

Construction rules and regulations prohibit fastening rods in application areas and places where the structure is subject to maximum load. Installation of rods can be carried out both with and without binding wire. As for the reinforcement, the cross-section of which is 25-30 millimeters, here experts recommend using a coupling or pressed connection.

Between the rods that will overlap, there must be a distance of at least 25 millimeters or more, then the concrete can fill the entire frame of the future structure. The overlap can also be made using a knitting wire, in which case the distance between the rods can be equal to 0. The largest distance between the rods must be chosen so that it does not exceed 4 diameters of the reinforcing elements. As for the distance between pairs of joints, with this type of fastening it should be at least 30 millimeters, but also at least two diameters.

Mechanical connection method

Reinforcement diagram where stiffeners are used. Under number “1” is indicated reinforced mesh, numbered “2” – vertical rods.

If the rods are joined using a mechanical connection, then a hydraulic press will be a mandatory requirement. As for materials, this process requires rods, as well as threaded and pressed couplings.

Mechanical connection technology is one of the simplest; installation proceeds as follows:

1. A coupling must be placed on the rod.
2. Next, crimping occurs using a press.
3. For the next reinforcement bar, the work pattern is repeated.

As you can see, the process goes quite quickly. Thick-walled pipes can be used as an alternative to couplings. Couplings with a central partition are also used. A mechanical connection is used for rods of different diameters, since the work involves Hydraulic Press. The main advantage of this method for private construction is that you can handle the installation yourself. You don’t have to hire workers, since even a novice builder can operate the press

Overlapping values

The length of the rods primarily depends on the cross-section of the reinforcement, so the following table, which contains the main dimensions according to SNiP, will help you make your choice:

In SNiP you can also find tables that indicate the length of the anchorage, depending on the brand of concrete mixture. The length may also depend on the type of reinforcement (tensile or compression). For example, for the brand cement mixture M450 length is 20 centimeters. The length for lower quality concrete M250 will be already 158 centimeters.

The photo shows the joining; an overlap is used here. A professional should determine the type of connection for your structure; for example, for heavy structures it is better to use a coupling connection.

Now you know how many diameters the minimum distance is and how long the rods are, depending on the brand of concrete mixture. It remains to go through several important points of SNiP:

• If overlap is used, then additional rods must be used during installation - this is a mandatory requirement of SNiP;

The overlap, where the connection is cross-shaped, should be made using annealed wire or clamps.

Methods for joining reinforcement updated: February 26, 2018 by: zoomfund

When connecting steel rods, reinforcing a strip foundation, many people have a natural question: how to correctly overlap the reinforcement, and what its length should be. After all correct assembly metal load-bearing frame will prevent deformation and destruction of the monolithic concrete structure from the loads acting on it and increase its trouble-free service life. What are technical features performing butt joints, we will consider in this article.

Types of lap reinforcement connections

According to the requirements of SNiP, the concrete foundation must have at least two continuous, unbroken reinforcement contours. Execute this condition in practice, it is possible to overlap the reinforcing rods. In this case, connections at joints can be of several types:

• Lap without welding
• Welded and mechanical connections.

The first connection option is widely used in private housing construction due to its ease of execution, availability and low cost of materials. In this case, the common reinforcement class A400 AIII is used. The joining of overlapping reinforcing bars without the use of welding can be carried out both with and without the use of tying wire. The second option is most often used in industrial housing construction.

According to building codes and regulations, the connection of overlapping reinforcement during tying and welding requires the use of rods with a diameter of up to 40 mm. The American Cement Institute ACI allows the use of rods with a maximum cross-section of 36mm. For reinforcing rods whose diameter exceeds the specified values, the use of overlap joints is not recommended due to the lack of experimental data.

According to construction regulations, it is prohibited to overlap reinforcement when knitting and welding in areas of maximum load concentration and places of maximum stress on metal rods.

Joining overlapping reinforcing bars by welding

For country house construction overlapping reinforcement welding is considered expensive pleasure, due to the high cost of metal rods of the A400C or A500C brand. They belong to the weldable class. Which significantly increases the cost of materials. It is unacceptable to use rods without the “C” index, for example: the common class A400 AIII, since when heated the metal significantly loses its strength and corrosion resistance.

However, if you decide to use weldable class rods (A400C, A500C, B500C), their connections should be welded with electrodes of 4...5 mm diameter. The length of the weld seam and the overlap itself depends on the class of reinforcement used.

Based on the data presented, it can be seen that when using steel rods of class B400C for knitting, the amount of overlap, respectively, weld, will be 10 diameters of the welded reinforcement. If ᴓ12 mm rods are taken for the load-bearing frame of the foundation, then the length of the seam will be 120 mm, which, in fact, will correspond to GOST 14098 and 10922.

According to American codes, reinforcing bar crosses cannot be welded. Effective loads on the foundation can cause possible ruptures, both the rods themselves and the places where they are connected.

Overlapping reinforcement connection when knitting

In cases of using common rods of the A400 AIII brand, in order to transfer the calculated forces from one rod to another, a connection method without welding is used. In this case, the places where the reinforcement overlaps are connected with a special wire. This method has its own characteristics and special requirements are placed on it.

Reinforcement overlap options

In accordance with the current SNiP, non-welding connection of rods during the installation of a reinforced concrete frame can be made using one of the following options:

• Overlay of profile rods with straight ends;
• Overlap of a reinforcing profile with a straight end with welding or installation throughout the entire bypass of transversely located rods;
• With curved ends in the form of hooks, loops and claws.

Such connections can be used to knit profiled reinforcement with a diameter of up to 40 millimeters, although the American standard ACI-318-05 allows the use of rods with a diameter of no more than 36 mm.

The use of bars with a smooth profile requires the use of lap joint options either by welding transverse reinforcement or using bars with hooks and tabs.

Basic requirements for making overlap joints

When performing overlapping reinforcement joints, there are rules defined by construction documentation. They define the following parameters:

• The size of the rod lining;
• Features of the location of the connections themselves in the body of the concreted structure;
• The location of adjacent bypasses relative to each other.

Taking these rules into account allows you to create reliable reinforced concrete structures, and increase the period of their trouble-free operation. Now about everything in more detail.

Where to place reinforcement overlap joints when knitting

SNiP does not allow the location of overlapping fittings in areas heaviest load on them. It is not recommended to place joints in places where steel rods experience maximum stress. It is best to place all connecting rod connections in unloaded areas of reinforced concrete, where the structure is not under stress. When pouring a strip foundation, the bypass ends of the reinforcement are placed in places with minimal torque and minimal bending moment.

If it is not technologically possible to fulfill these conditions, the length of the overlap of the reinforcing rods is taken at the rate of 90 diameters of the joined rods.

What is the amount of overlap of reinforcement when knitting?

Since the overlap of the reinforcement is determined by the technical documentation, the length of the joint connections is clearly indicated there. In this case, the values ​​can vary not only from the diameter of the rods used, but also from such indicators as:

• Nature of the load;
• Concrete grade;
• Reinforcing steel class;
• Connection points;
• Purpose of reinforced concrete products (horizontal slabs, beams or vertical columns, pylons and monolithic walls).

In general, the length of the overlap of reinforcement bars during tying is determined by the influence of the forces arising in the rods, the perceived adhesion forces with concrete acting along the entire length of the joint, and the forces that provide resistance in the anchoring of the reinforcing bars.

The fundamental criterion when determining the length of the reinforcement overlap during tying is its diameter.

For the convenience of calculating the overlap of reinforcing bars when knitting a load-bearing frame monolithic foundation We suggest using a table with the indicated diameter values ​​and their overlap. Almost all values ​​are reduced to 30 times the diameter of the rods used.

The amount of reinforcement inlet in diameters
Diameter of reinforcing steel A400, mm	Overlap amount
	in diameters	in mm
10	30	300 mm
12	31,6	380 mm
16	30	480 mm
18	32,2	580 mm
22	30,9	680 mm
25	30,4	760 mm
28	30,7	860 mm
32	30	960 mm
36	30,3	1090 mm

Depending on loads and purpose reinforced concrete products the length of the overlap joints of the steel rod increases:

Depending on the grade of concrete and the nature of the load used for pouring the monolithic foundation strip and other reinforced concrete elements, the minimum recommended values ​​for the bypass of reinforcement during the binding process will be as follows:

For compressed concrete
Diameter of reinforcing steel A400 used in compressed concrete, mm
	M250 (B20)	M350 (B25)	M400 (B30)	M450 (B35)
10	355	305	280	250
12	430	365	335	295
16	570	490	445	395
18	640	550	500	445
22	785	670	560	545
25	890	765	695	615
28	995	855	780	690
32	1140	975	890	790
36	1420	1220	1155	985

For stretched concrete
Diameter of reinforcing steel A400 used in tensile concrete, mm	Length of overlap of reinforcing bars for concrete grades (concrete strength class), in mm
	M250 (B20)	M350 (B25)	M400 (B30)	M450 (B35)
10	475	410	370	330
12	570	490	445	395
16	760	650	595	525
18	855	730	745	590
22	1045	895	895	275
25	1185	1015	930	820
28	1325	1140	1040	920
32	1515	1300	1185	1050
36	1895	1625	1485	1315

How to position reinforcement bypasses relative to each other

To increase the strength of the foundation's load-bearing frame, it is very important to correctly position the overlapping reinforcement relative to each other in both planes of the concrete body. SNiP and ACI recommend spacing connections so that there are no more than 50% bypasses in one section. In this case, the take-off distance, as defined in regulatory documents, must be at least 130% of the length of the connecting connection of the rods.

If the centers of overlap of the knitted reinforcement are within the specified value, then it is considered that the connection of the rods is located in the same section.

According to ACI 318-05 standards mutual arrangement The connecting connections must be at least 61 centimeters apart. If the distance is not maintained, then the likelihood of deformation of the concrete monolithic base from the loads exerted on it during the construction of the building and its subsequent operation increases.