1.什么是高强螺栓
1. What is high-strength bolt
高强螺栓，施工中所说的高强螺栓是高强度摩擦预紧螺栓的简称。在日常沟通中，仅仅是简略了“摩擦(Friction)”“预紧(Grip)”两个词，却造成了许多工程技术人员对高强螺栓基本定义的理解，产生了误区。
High strength bolts, referred to in construction as high-strength bolts, are short for high-strength friction pre tensioned bolts. In daily communication, simply abbreviating the words "friction" and "Grip" has caused many engineering and technical personnel to misunderstand the basic definition of high-strength bolts.
高强螺栓.jpg
High strength bolts.jpg
颠覆一：
Disruption 1:
误区：材料等级超过8.8级的螺栓，就是”高强螺栓“。
Misunderstanding: Bolts with a material grade exceeding 8.8 are considered "high-strength bolts".
高强螺栓和普通螺栓的核心区别并不在于使用材料的强度，而是受力的形式。本质是是否施加预紧力，并利用静摩擦力抗剪。(1)*实际上在英标规范，美标规范中提到的高强螺栓(HSFG BOLT)只有8.8级和10.9级两种(BS EN 14399 / ASTM-A325&ASTM-490)，而普通螺栓却有包含有4.6，5.6，8.8，10.9，12.9等(BS 3692 11款表2);由此可见，材料强度高低并不是区别高强螺栓与普通螺栓的关键。
The core difference between high-strength bolts and ordinary bolts is not the strength of the materials used, but the form of force applied. The essence is whether to apply preload and use static friction to resist shear. (1) In fact, in the British standard specifications, the American standard specifications only mention two types of high-strength bolts (HSFG BOLT): grade 8.8 and grade 10.9 (BS EN 14399/ASTM-A325&ASTM-490), while ordinary bolts include 4.6, 5.6, 8.8, 10.9, 12.9, etc. (Table 2 of BS 3692 Clause 11); It can be seen that the strength of the material is not the key to distinguishing high-strength bolts from ordinary bolts.
2.正确理解“高强”，强在何处
2. Correctly understand "high strength" and where it lies
按照GB50017，计算单个普通螺栓(B类)8.8级和高强螺栓8.8级抗拉及抗剪强度。
According to GB50017, calculate the tensile and shear strength of individual ordinary bolts (Class B) with grade 8.8 and high-strength bolts with grade 8.8.
通过计算我们可以看到，相同等级的情况下，普通螺栓的抗拉强度和抗剪强度的设计值都要高于高强螺栓。那么高强螺栓，“强”在哪里?
Through calculation, we can see that under the same grade, the design values of tensile strength and shear strength of ordinary bolts are higher than those of high-strength bolts. So where is the strength of high-strength bolts?
为回答这一个问题，必须从两种螺栓的设计工作状态入手，研究其弹塑性变形的规律，并理解到设计破坏时的极限状态。
To answer this question, it is necessary to start with the design working states of the two types of bolts, study their elastic-plastic deformation laws, and understand the limit state at the time of design failure.
普通螺栓和高强螺栓工作状态下应力应变曲线
Stress-strain curves of ordinary bolts and high-strength bolts under working conditions
设计破坏时的极限状态
Ultimate state at design failure
普通螺栓：螺杆本身发生超过设计允许的塑性变形，螺杆被剪坏。
Ordinary bolt: The screw itself undergoes plastic deformation that exceeds the design tolerance, resulting in the screw being sheared out.
普通螺栓连接，开始承受剪力前连接板间就会发生相对滑移，继而螺栓杆和连接板接触，发生弹塑性形变，承受剪力。
For ordinary bolted connections, relative slip occurs between the connecting plates before they begin to bear shear force, and then the bolt rod contacts the connecting plate, causing elastic-plastic deformation and bearing shear force.
高强螺栓：有效摩擦面间的静摩擦力被攻克，两块钢板发生相对位移，设计考量上即为破坏。
High strength bolt: The static friction force between the effective friction surfaces is overcome, and the two steel plates undergo relative displacement, which is considered as failure in design considerations.
高强螺栓连接，摩擦力承受剪力，当荷载增大到摩擦力不足以抵抗剪力，静摩擦力被攻克，连接板发生相对滑移(极限状态)。但此时虽然破坏，但螺栓杆与连接板发生接触，依然可以利用其本身的弹塑性形变，承受剪力。
In high-strength bolt connections, the frictional force first bears the shear force. When the load increases to a point where the frictional force is insufficient to resist the shear force, the static frictional force is overcome, and the connecting plate undergoes relative slip (ultimate state). But although it is damaged at this time, the bolt rod can still use its own elastic-plastic deformation to withstand shear force when in contact with the connecting plate.
(3)颠覆二：
(3) Subversion 2:
误区：高强螺栓的承载能力高于普通螺栓，是为”高强“。
Myth: High strength bolts have a higher load-bearing capacity than ordinary bolts and are considered "high strength".
由单个螺栓的计算可知，高强螺栓抗拉和抗剪的设计强度均低于普通螺栓。其高强实质是：正常工作时，节点不允许发生任何相对滑移，即：弹塑性变形小，节点刚度大。
According to the calculation of a single bolt, the design strength of high-strength bolts in terms of tensile and shear strength is lower than that of ordinary bolts. The essence of its high strength is that during normal operation, nodes are not allowed to experience any relative slip, that is, small elastic-plastic deformation and high node stiffness.
可见：在给定设计节点荷载的情况下，用高强螺栓设计的节点并不一定能节省螺栓使用数量，但是其变形小，刚度大，储备高。适合用主梁，等要求节点刚度较大的位置，符合“强节点，弱杆件”的基本抗震设计原理。
It can be seen that under a given design node load, nodes designed with high-strength bolts may not necessarily save on the number of bolts used, but they have small deformation, high stiffness, and high safety reserves. Suitable for using main beams and other locations that require high node stiffness, in accordance with the basic seismic design principle of "strong nodes, weak members".
高强螺栓之强，并非在于其本身的承载能力设计值，而是表现于其设计节点的刚度大，性能高，抗破坏的能力强。
The strength of high-strength bolts is not determined by their designed load-bearing capacity, but by the high stiffness, high safety performance, and strong resistance to failure of the designed nodes.
3.高强螺栓的对比
3. Comparison of high-strength bolts
普通螺栓和高强螺栓由于其设计的受力原理不同，其在施工检验方法上有极大的区别。
Ordinary bolts and high-strength bolts have significant differences in construction inspection methods due to their different design stress principles.
同等级普通螺栓各项机械性能要求均比高强螺栓略高，但高强螺栓较普通螺栓多一项冲击功的验收要求。
The mechanical performance requirements of ordinary bolts of the same grade are slightly higher than those of high-strength bolts, but high-strength bolts have an additional acceptance requirement for impact energy compared to ordinary bolts.
标识样式对比
Comparison of logo styles
普通螺栓和高强螺栓的标示是对同等级螺栓现场识别的基本方法。由于英美标准中对于高强螺栓扭矩值计算的取值并不相同，所以识别两种标准的螺栓也有必要。
The identification of ordinary bolts and high-strength bolts is the basic method for on-site identification of bolts of the same grade. Due to the different values for calculating the torque value of high-strength bolts in British and American standards, it is also necessary to identify bolts from both standards.
对比
Price comparison
高强螺栓：(M24，L60，8.8级)
High strength bolts: (M24, L60, Grade 8.8)
普通螺栓：(M24，L60，8.8级)
Ordinary bolt: (M24, L60, Grade 8.8)
可见普通螺栓大约为高强螺栓的70%，结合其验收要求的对比，可以得出，其溢价部分就应该是为了保证材料的冲击功(韧性)性能。
It can be seen that ordinary bolts are about 70% of the price of high-strength bolts. Based on the comparison of their acceptance requirements, it can be concluded that the premium part should be to ensure the impact energy (toughness) performance of the material.
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