As we all know, the role of traditional supports and hangers in the electromechanical system is load-bearing. The principle is the common sense that gravity acts downward. How does the seismic support and hanger play an anti-seismic role?

　　 Through GB 50981-2014 "Code for Electrical and Mechanical Seismic Design of Buildings", we can know that seismic supports and hangers mainly guarantee the safety of support and hanger systems through the function of resisting horizontal seismic forces.

　　How to understand "resistance to horizontal seismic force"?

　　 1. How does the earthquake work and how does the vibration cause damage to the building?

　　 First, we need to know what an earthquake is. According to the explanation of Baidu Encyclopedia, we can know that earthquakes are vibrations caused by the release of energy in the earth's crust, which affect or even destroy human life through seismic waves.

　　 So what are seismic waves? According to the current level of earthquake research in the world, seismic waves can be divided into three forms: longitudinal waves (P waves), transverse waves (S waves), and surface waves (L waves). Longitudinal waves are propulsion waves, which cause the ground to vibrate up and down, and are relatively weakly destructive. Transverse waves are shear waves, which cause the ground to shake back and forth, which is more destructive. Surface waves are the most destructive mixed waves generated by the excitation of longitudinal waves and transverse waves when they meet on the surface.

　　 In the field of electromechanical seismic resistance, it is widely understood as: the gravity support and hanger play the role of resisting and alleviating the vertical seismic force (ie longitudinal wave). The seismic support and hanger, through its unique diagonal brace structure, greatly resist and relieve the horizontal seismic force (ie, transverse wave).

　　 2. The action mode of the seismic support and hanger, how does the seismic brace resist the horizontal seismic force

　　 As we all know, seismic supports and hangers are reinforced by seismic diagonal braces to resist earthquakes.

It is precisely because of the existence of the seismic brace that the pipeline support and hanger system, which is originally unfettered in the horizontal direction, can be safe and reliable in the event of an earthquake, preventing the pipeline support and hanger system from collapsing and falling, causing serious secondary occurrence disaster.

　　From a simple mechanics point of view, we can do a simple disassembly analysis of anti-seismic brace.

From the figure above, we can clearly see that the seismic brace has an oblique upward pulling force on the overall support. According to the force decomposition principle, this diagonal pulling force can be decomposed into a horizontal force Fx and a vertical force Fy , The horizontal force is the load effect value of horizontal earthquake, and the vertical force is the load effect value of gravity.

When 　　 is applied in practice, the anti-seismic brace has the function of "anti-seismic", also according to the above principle. If there is no seismic brace, the pipeline support and hanger system is not bound in the horizontal direction. Once an earthquake occurs, it is conceivable that the overall support and hanger system will produce disorderly and irregular shaking, gradually taking root or connecting nodes of the structure Fracture and fall off occurred, causing irreparable losses.

　　 3. Whether the anti-seismic effect of diagonal brace is related to the bearing gravity, and whether there is gravity on the diagonal brace

　　 From the second point, we can know that the seismic brace has a certain gravity load effect in mechanics. Of course, the greater the gravity carried by the pipeline support system, the greater the value of the gravity effect on the seismic brace, so the seismic effect of the diagonal brace does have a certain relationship with the bearing gravity.

　　 However, one thing we need to pay attention to is that the functionality of seismic supports and hangers is mainly "seismic resistance" rather than "load bearing". The prerequisite for the installation of seismic supports and hangers is that the gravity supports and hangers must meet the conditions and can meet the gravity action of all the pipelines and media in the vertical direction. That is, the gravity effect on the seismic supports and hangers can also meet the functional requirements. In layman's terms, it can be summarized as: there is gravity on the seismic brace, but we do not consider the gravity effect of the seismic support and hanger when we design and calculate it, that is, the gravity co-support is not considered. (Except for special cases, there may be gravitational co-existence in some narrow spaces.)

　　4. Functional analysis of seismic connectors

　　 Seismic connectors generally have the following forms

　　 From the above, we can know that the seismic connection members basically adopt the form of hinges, which provide a buffer-like function when an earthquake occurs, avoiding the possible breakage caused by a purely rigid connection.

　　 The place where the anti-seismic connecting member is connected to the concrete building structure generally adopts rear-expanded anchor bolts. This kind of anchor bolts have a good anchoring effect and have higher connection strength than conventional expansion bolts.

　　The composition of the building electromechanical anti-seismic system includes riser tube bundles, steel beams and purlin clamps, ring pipe cranes, earthquake-proof diagonal bracing systems, earthquake-proof steel hangers and supports, etc.

　　The surface of the base material in the anchoring zone should be solid and flat, and there should be no defects such as sanding, shelling, honeycomb, pitted surface, oil activity, etc., which affect the anchoring bearing capacity;

　　The concrete strength grade of the stick should reach C30 or above within the range of anchoring depth;

　　 The anchoring operation should meet the design requirements of the anchor bolt, and the steel bar detector should be used to check before drilling to avoid the hole position from encountering hidden objects such as steel bars and line pipes.

　　 Seismic supports and hangers fixed on steel columns and beams should be connected by special clamps.

　　The deviation of the verticality of the fully threaded boom after installation shall not be greater than 4 degrees.

　　 When the connecting nut is connected with the fully threaded boom and anchor bolt, the threaded end is first drawn according to the screwing depth, and the screwing depth should reach 45% of the length of the connecting nut:

　　The distance between the diagonal support and the hanger of the single pipe seismic support and hanger shall not exceed 10cm;

　　 The connection between the pipe clamp and the pipeline should be provided with shockproof insulating rubber pads to prevent electrochemical corrosion at the connection. The connection between the pipe clamp and the pipeline should be stable:

　　 The screw nut should be tightened according to the design torque to prevent loosening.

　　 Seismic support design process:

　　Assembled/finished bracket system is a bracket product that is assembled on site with factory prefabricated parts, using standard connectors and standard channel steel, as shown below:

　　 The acceptance and quality of fabricated/finished stent products and supporting anchor products shall meet (not limited to) the requirements of the following standards and current national standards:

　　 GB50011-2010 "Code for Seismic Design of Buildings"

　　 GB50981-2014 "Code for Seismic Design of Building Mechanical and Electrical Engineering"

　　 GB50242-2002 "Code for Construction Quality Acceptance of Building Water Supply and Drainage and Heating Engineering"

　　 GB50234-2002 "Code for Quality Acceptance of Ventilation and Air Conditioning Engineering"

　　 "Code for Construction and Acceptance of Automatic Sprinkler System" GB50261-2005

　　 "Code for Construction Quality Acceptance of Building Electrical Engineering" GB50303-2002

　　《03S402 Indoor Pipe Bracket and Hanger》

　　Note: The above specification requirements have been updated.

　　 Seismic Support Specifications:

　　GB50011-2010:

　　 Article 1.0.2 The buildings in areas where the seismic fortification intensity is 6 degrees and above must be designed for earthquake resistance.

　　 3.7.1 Non-structural components, including building non-structural components and auxiliary mechanical and electrical equipment of buildings, themselves and their connection with the main body of the structure shall be subjected to seismic design.

　　Chapter 13 Calculation and anti-seismic measures of seismic design of non-structural members.

　　GB50981-2014:

　　 Article 1.0.4 The mechanical and electrical engineering of buildings in areas where the seismic fortification intensity is 6 degrees and above must be designed for earthquake resistance.

　　 Article 5.1.4 The anti-fume exhaust duct, accident ventilation duct and related equipment shall adopt seismic supports and hangers.

　　 Article 7.4.6 The shared antennas installed on the roof of buildings shall adopt safety protection measures to prevent equipment or components from falling and hurting people after being damaged by earthquakes.

　　 GB50981-2014 stipulates the setting range of seismic supports and hangers:

　　 Air conditioning units, fans and other equipment with gravity greater than 1.8kN in the suspended pipeline;

　　 Gas pipeline above DN25;

　　 Domestic water supply and fire-fighting pipes above DN65, pipe accessories with a flexible connection of 9kg~25kg, and pipe accessories with a rigid connection of more than 25kg;

　　 Air duct system with rectangular cross-sectional area greater than or equal to 0.38m2 and circular diameter greater than or equal to 0.7m;

　　 For electrical piping with an inner diameter greater than or equal to 60mm and a cable ladder frame, cable trough box and busway with a gravity greater than or equal to 150N/m;

　　All specifications of anti-exhaust air ducts and accident ventilation ducts and their equipment.

　　Pipeline selection:

　　 Water supply and drainage, fire fighting, heating, ventilation, air conditioning, gas, heating, electricity, communications;

　　Select according to different system pipe specifications or weight;

　　 can be set up with a single pipe or with multiple pipes sharing a comprehensive seismic support;

　　 The article on page 41 of the specification explains:

　　 Equipment with gravity greater than 1.8KN in the suspended pipeline;

　　 Domestic water supply and fire fighting piping system above DN65; (for water pipes)

　　 Air duct system with rectangular cross-sectional area greater than or equal to 0.38 square meters and circular diameter greater than or equal to 0.7m;

　　For electrical piping with an inner diameter greater than or equal to 60mm;

　　 Cable ladders, cable trough boxes and bus ducts with a gravity greater than or equal to 150N/m;

　　 Gas pipeline with inner diameter greater than or equal to 25mm;

　　 Bracket layout and related requirements:

　　 The maximum spacing of seismic supports and hangers Table 8.2.3

　　The maximum seismic reinforcement spacing of the reconstruction project is half of the value in the above table;

　　Note: This table is the basic basis for the design of the seismic support plan layout and is also the core content of the seismic support design in the code.

　　 can be interpreted as:

　　 The spacing of seismic supports may not be the maximum spacing of pipeline types;

　　The distance is related to the magnitude of the earthquake action. When αEK is greater than 1.0, the bracket needs to be encrypted;

　　 is related to the angle of the diagonal brace, when the vertical angle of the diagonal brace is less than 45 degrees, the bracket needs to be encrypted;

　　3.4.2 When calculating two electromechanical equipment that are connected together and require different seismic measures, seismic design should be carried out according to higher requirements. When the connection of the building electromechanical equipment is damaged, it shall not cause the failure of the auxiliary electromechanical equipment with higher requirements connected to it.

　　Note: It is better to understand, the comprehensive seismic support is calculated and fortified according to the pipeline of higher standards.

　　 Seismic support and hanger layout principle:

　　8.3.1 Each horizontal straight pipeline shall be provided with lateral seismic supports and hangers at both ends.

　　8.3.2 When the distance between two lateral seismic supports and hangers exceeds the maximum design distance, additional lateral seismic supports and hangers shall be added in the middle.

8.3.3 At least one longitudinal seismic support and hanger shall be installed for each section of horizontal straight pipeline. When the distance between the two longitudinal seismic supports and hangers exceeds the maximum design spacing, longitudinal seismic supports and hangers shall be added in accordance with the spacing required in Article 8.2.3 of this code. frame.

　　 8.3.5 For rigidly connected horizontal pipelines, the allowable longitudinal offset value between two adjacent seismic supports and hangers. The following requirements should be met:

　　1 Water pipes and wire casings shall not exceed 1/16 of the maximum lateral support and hanger spacing;

　　2 Air ducts, cable ladders, cable trays and cable trough boxes must not exceed twice their width.

　　 Example: The maximum offset calculation is 12/16 = 0.75 meters, this condition is very harsh.

8.3.6 Horizontal pipelines should be installed with lateral seismic supports and hangers within 0.6m from the turning point; if diagonal braces directly act on the pipeline, they can be used as the longitudinal seismic supports and hangers of the other side of the pipeline; The distance between hangers should be calculated as follows:

　　 where: L is the distance between the next longitudinal seismic support and hanger (m); L1 is the distance between the longitudinal seismic support and hanger (m); L2 is the lateral seismic support and hanger distance (m).

　　 Example: L1 = 24 meters, L2 = 12, then: calculate L = 18.6 meters

　　 8.3.7 When horizontal pipelines are connected to ground equipment through vertical pipelines, flexible connections are adopted between the pipelines and equipment. Set lateral support within 600mm of the horizontal pipeline from the vertical pipeline. Seismic support should be provided at the bottom of the vertical pipeline greater than 0.15m from the ground.

　　 3.4.4 The calculation method of seismic action of building electrical and mechanical engineering shall meet the following requirements:

　　The seismic force of each member and component should be applied to its center of gravity, and the horizontal seismic force should be along any horizontal direction;

The earthquake action caused by the self-gravity of the building electromechanical engineering can be calculated by the equivalent lateral force method; for the building electromechanical engineering supported on different floors or on both sides of the seismic joint, in addition to the seismic action caused by its own gravity, the earthquake support point should also be calculated at the same time The effect of the relative displacement between the two;

When the self-vibration period of the system of building electromechanical equipment (including brackets) is greater than 0.1s and its gravity exceeds 1% of the floor gravity, or the gravity of the building electromechanical equipment exceeds 10% of the floor gravity, it is advisable to enter the overall structure model for seismic calculation. The floor response spectrum method can also be used for calculation. Among them, the equipment that is inelastically connected to the floor can directly use the equipment and the floor as a mass point to be included in the analysis of the entire structure to obtain the seismic effect of the equipment.

　　It is a simple and feasible method to calculate by equivalent lateral force method.

　　 When the equivalent lateral force method is adopted, the standard value of horizontal seismic action is calculated according to the following formula:

　　F=γηζ1ζ2αmaxG (3.4.5)

　　F: The standard value of horizontal seismic action applied to the center of gravity of electromechanical engineering facilities in the most unfavourable direction;

　　Γ: non-structural component function coefficient, implemented in accordance with 3.4.1 of this code;

　　Η: Non-structural component category coefficient, implemented in accordance with 3.4.1 of this code;

　　Ζ1: state coefficient; 2.0 should be adopted for any equipment and flexible system whose supporting point is lower than the center of mass, and 1.0 for other cases; (here: hangers should all be 1.0)

　　Ζ2: position coefficient, the vertex of the building should be 2.0, the bottom should be 1.0, and it should be linearly distributed along the height; (the basement of the building should be 1.0)

　　Αmax: the maximum value of earthquake influence coefficient; it can be adopted in accordance with the provisions of frequent earthquakes in Article 3.3.5 of this code;

　　G: Sectional pipeline weight: 1) The gravity of the pipeline and its rated load medium shall be included; 2) The weight of the branch shall be included;

　　 Horizontal seismic force comprehensive coefficient: αEk=γηζ1ζ2αmax

　　 Note: The calculated αEk required for seismic supports and hangers is not less than 0.5.

　　3.5.1 The basic combination of seismic action effects (including the effects caused by its own gravity and the effects caused by the relative displacement of the support) and other load effects of the building electromechanical engineering facility engineering should be calculated as follows S=γGSGE+γEhSEhk (3.5.1)

　　S: Design value of internal force combination of mechanical and electrical engineering facilities or components, including combined design value of bending moment, axial force and shear force;

　　ΓG: partial coefficient of gravity load, 1.2 should be adopted in general;

　　ΓEh: is the partial coefficient of horizontal seismic action, which is 1.3;

　　 Senk: The effect of the standard value of horizontal seismic action.

　　Note: Generally, only the horizontal earthquake action needs to be considered in the calculation of seismic support.

　　 10.2.2 In the seismic check calculation of mechanical and electrical engineering facilities, the friction force shall not be used as the resistance to earthquake action; the seismic adjustment coefficient of bearing capacity can be 1.0, and the following requirements should be met: S≤R (R is the design value of component bearing capacity)

　　Note: The bearing capacity of the seismic support is greater than the seismic action of the pipeline.

　　Member force: Two types of rod force states caused by the horizontal force direction.

　　The force of the rod is transmitted to the structure by the connecting parts, the vertical rod and the diagonal brace, and the anchor bolt;

　　The bracket design should ensure the connection (accessories and supports, etc.).

　　 Strength check under seismic force

　　Strength check calculations of diagonal braces and seismic connection members (compression check and fitting strength);

　　 The strength of the boom;

　　The strength check calculations of various anchors, including diagonal bracing anchors, boom anchors, etc.;

　　 The strength of the tube bundle;

　　 Bracket structure regulations:

　　8.3.4 The distance between the diagonal brace of the seismic support and hanger shall not exceed 0.1m;

　　8.3.11 For the diagonal bracing installation of lateral and longitudinal seismic supports and hangers, the vertical angle should be 45° and not less than 30°;

　　 3.1.8 Flexible connections or other effective measures shall be adopted for the pipes of building electrical and mechanical engineering that pass through the seismic isolation layer, and seismic supports shall be installed on both sides of the seismic isolation layer.

　　8.3.13 The pipe laid along the wall can be used as a lateral seismic support and hanger when it is provided with brackets and supports into the wall and the pipe clamp can fasten the circumference of the pipe.

　　8.3.14 The setting of single pipe (pole) seismic supports and hangers shall meet the following requirements:

　　1) The horizontal pipeline connecting the riser should be set with the first seismic hanger within 0.6m of the riser;

　　2) When the length of the riser exceeds 1.8m, four-way seismic supports and hangers shall be installed at the top and bottom of the riser; when the length is greater than 7.6m, seismic supports and hangers shall be added in the middle;

　　3) When the riser passes through the casing to pass through the structure floor, the casing can restrict the horizontal movement of the pipe and can be used as a horizontal four-way seismic support;

　　4) When the mass of the accessories installed in the pipeline exceeds 25kg, lateral and longitudinal seismic supports and hangers should be installed;

　　8.3.12 The installation of the diagonal bracing of the seismic hanger should not deviate from its centerline by 2.5°;

　　 8.3.9 It is not allowed to install anti-seismic supports on non-structure main parts, such as lightweight partition walls;

　　8.3.15 The setting of door-type seismic supports and hangers shall meet the following requirements:

　　1) The door-type seismic support and hanger shall have one lateral seismic support and hanger or two longitudinal seismic supports and hangers;

　　2) For the same load-bearing hanger to hang multi-layer door hangers, the load-bearing hangers shall be separately reinforced and seismic brace shall be provided;

　　3) The lateral and longitudinal diagonal braces of the door-type seismic supports and hangers should be installed at the connection of the upper beam or load-bearing hanger;

　　4) When the mass of the accessories on the pipeline exceeds 25kg and is rigidly connected to the pipeline, or when the mass of the accessories is 9kg to 25kg and is connected to the pipeline in flexible, lateral and longitudinal seismic supports and hangers should be installed;

　　GB-50981-2014 Code for seismic design of building electrical and mechanical engineering

　　 Article 8.1.2 stipulates: All components constituting the seismic supports and hangers should be finished components, and the structure of the connecting fasteners should be easy to install.

　　Article 3.5.2 stipulates: Construction of mechanical and electrical engineering facilities for earthquake resistance checking

　　 Article 3.3.2 of JGJ339-2015 Code for Seismic Design of Non-structural Members