What is the concrete content of how to place the longitudinal prestressing steel bar? Here is your answer.

　　（1）预应力钢筋的净距。先张法预应力钢筋之间的净距离应根据浇注混凝土、施加预应力及钢筋锚固等要求断定。预应力钢筋之间的净距离不该小于其公称直径或等效直径的1.5倍，且应契合下列规则：对热处理钢筋及钢丝，不该小于15mm；对三股钢绞线，不该小于20mm；对七股钢绞线，不该小于25mm。

　　(1) Net distance of prestressing steel bar. The net distance between pre-tensioned tendons should be determined according to the requirements of pouring concrete, applying prestressing force and reinforcing bar anchorage. The net distance between prestressing steel bars should not be less than 1.5 times of their nominal diameter or equivalent diameter, and should conform to the following rules: for heat treated steel bars and steel wires, it should not be less than 15 mm; for three strands, it should not be less than 20 mm; and for seven strands, it should not be less than 25 mm.

　　（2）钢筋、钢丝的锚固。先张法预应力混凝土构件应确保钢筋与混凝土之间有牢靠的粘结力，一般宜选用变形钢筋、刻痕钢丝、钢绞线等类钢材。当选用光面圆钢丝作预应力配筋时，应根据钢丝强度、直径及构件之受力特色选用适当办法，以确保钢丝在混凝土中牢靠地锚固，防止钢丝滑动，并应考虑在预应力传递长度规模内抗裂性较低的晦气影响。

　　(2) Anchorage of steel bar and steel wire. The pre-tensioned pre-stressed concrete members should ensure that there is a strong bonding force between reinforcement and concrete. Generally, deformed steel bars, notched steel wires and steel strands should be selected. When choosing smooth circular steel wire as prestressing reinforcement, appropriate methods should be selected according to the strength, diameter and stress characteristics of steel wire, so as to ensure that steel wire is firmly anchored in concrete and prevent steel wire from sliding, and the obscure effect of low crack resistance in the scale of prestressing transfer length should be considered.

　　（3）后张法预应力钢丝束、钢绞线束的预留孔道应契合下列规则：

　　(3) The reserved passages of post-tensioned prestressing tendons and stranded tendons shall conform to the following rules:

　　①对预制构件，孔道之间的水平净距离不宜小于50mm；孔道构件边际的净距离不宜小于30mm，且不宜小于孔道直径的一半。

　　For prefabricated members, the net horizontal distance between the channels should not be less than 50 mm, and the net distance between the channels and the edge of the components should not be less than 30 mm, and should not be less than half of the diameter of the channels.

　　②在框架梁中，预留孔道在竖直方向的净距离不该小于孔道外径，水平方向的净距离不该小于1.5倍孔道外径；从孔壁算起的混凝土保护层厚度，梁底不宜小于50mm，梁侧不宜小于40mm.

　　(2) In the frame beam, the net distance of the reserved channel in the vertical direction should not be less than the outside diameter of the channel, and the net distance in the horizontal direction should not be less than 1.5 times the outside diameter of the channel; the thickness of the concrete protective layer calculated from the hole wall should not be less than 50 mm at the bottom of the beam and less than 40 mm at the side of the beam.

　　③预留孔道的内径应比预应力钢丝束或钢绞线束外径及需穿过孔道的连接器外径大10mm～15mm。

　　(3) The inner diameter of the reserved channel should be 10 mm to 15 mm larger than the outer diameter of the prestressing steel wire or strand bundle and the outer diameter of the connector that needs to pass through the channel.

　　④在构件两端及跨中应设置灌浆孔或排气孔，其孔距不宜大于12m。

　　(4) Grouting holes or exhaust holes should be installed at both ends and spans of components, and the spacing of holes should not be greater than 12 M.

　　⑤凡制作时需求预先起拱的构件，预留孔道宜随构件一起起拱。

　　Where pre-arched components are required during fabrication, the reserved channel should be arched together with the components.

　　（4）预应力混凝土构件端部安置钢筋应尽或许均匀安置，一起还应留意以下要求：

　　(4) Reinforcement bars should be placed evenly at the end of the pre-stressed concrete members. Together, the following requirements should be noted:

　　①宜将一部分预应力钢筋在接近支座处弯起，弯起的预应力钢筋宜沿构件端部均匀安置。

　　It is advisable to bend a part of the prestressing steel bar near the support, and the bending prestressing steel bar should be evenly placed along the end of the member.

　　②当构件端部预应力钢筋需会集安置在截面下部或会集安置在上部和下部时，应在构件端部0.2h（h为构件端部截面高度）规模内设置附加竖向焊接钢筋网、封闭式箍筋或其他方式的结构钢筋。

　　(2) When the pre-stressed steel bars at the end of a member need to be assembled at the lower part of the section or at the upper and lower parts, additional vertical welded steel nets, closed stirrups or other structural steel bars should be installed within the scale of 0.2h (h is the height of the section at the end of the member).

　　（5）对先张法预应力混凝土构件，预应力钢筋端部周围的混凝土应采取下列加强办法：

　　(5) For pre-tensioned pre-stressed concrete members, the concrete around the end of the pre-stressed steel bar should adopt the following strengthening methods:

　　①对单根配置的预应力钢筋，其端部宜设置长度不小于150mm且不少于4圈的螺旋筋；当有牢靠经验时，亦可利用支座垫板上的插筋代替螺旋筋，但插筋数量不该少于4根，其长度不宜小于120mm.

　　For a single pre-stressed steel bar, it is advisable to install spiral bars with length not less than 150 mm and no less than 4 circles at the end; when there is solid experience, the insertion bars on the support cushion plate can also be used to replace the spiral bars, but the number of insertions should not be less than 4, and the length should not be less than 120 mm.

　　②对分散安置的多根预应力钢筋，在构件端部10d（d为预应力钢筋的公称直径）规模内应设置3片～5片与预应力钢筋笔直的钢筋网。

　　(2) Three to five pieces of steel mesh with straight prestressing bars should be set at the end of the member for 10 days (d is the nominal diameter of the prestressing bars).

　　③对选用预应力钢丝配筋的薄板，在板端100mm规模内应适当加密横向钢筋。

　　(3) The transverse reinforcing bar should be properly encrypted in the 100mm scale of the plate end for the thin plate with prestressing steel wire reinforcement.

　　④对槽形板类构件，应在构件端部100mm规模内沿构件板面设置附加横向钢筋，其数量不该少于两根。

　　(4) For grooved slab members, additional transverse reinforcement should be installed along the slab surface of the member within the 100 mm scale at the end of the member, and the number of reinforcement should not be less than two.

　　⑤对预制肋形板，宜设置加强其整体性和横向刚度的横肋。端横肋的受力钢筋应弯入纵肋内。当选用先张长线法出产有端横肋的预应力混凝土肋形板时，应在设计和制作上采取防止放张预应力时端横肋产生裂缝的有用办法。

　　_For prefabricated ribbed slabs, transverse ribs should be set to strengthen their integrity and transverse stiffness. The reinforced bar of the end transverse rib should bend into the longitudinal rib. When the pre-tensioned long-line method is used to produce the prestressed concrete ribbed slabs with end transverse ribs, a useful method to prevent cracks in end transverse ribs should be adopted in design and fabrication.

　　（6）后张法预应力混凝土构件中，曲线预应力钢丝束、钢绞线束的曲率半径不宜小于4m；对折线配筋的构件，在预应力钢筋弯折处的曲率半径可适当减小。在后张法预应力混凝土构件的预拉区和预压区中，应设置纵向非预应力结构钢筋；在预应力钢筋弯折处，应加密箍筋或沿弯折处内侧设置钢筋网片。

　　(6) Curvature radius of curved prestressing steel wire bundle and strand bundle should not be less than 4m in post-tensioned prestressed concrete members, and the curvature radius of folded-wire reinforced components can be reduced appropriately at the bending point of prestressing steel bar. In the pre-tension zone and pre-compression zone of post-tensioned pre-stressed concrete members, longitudinal non-pre-stressed structural steel bars should be installed; in the bending zone of pre-stressed steel bars, stirrups should be tightened or steel meshes should be installed along the inside of the bending zone.