❶ 先张法：像拉皮筋一样造桥
适用场景：简支板桥（跨径小、梁高矮）
Pre-tensioning method: building bridges like stretching a leather band
Applicable scenario: Simply supported slab bridge (small span, short beam height)
核心逻辑：先拉钢筋，再浇混凝土，靠“黏结力”传递预应力！
Core logic: first pull the reinforcement, then pour the concrete, and rely on the “bond” to transmit the prestressing force!
施工三步曲：
1️⃣搭台拉筋：在预制厂用专用台座固定钢筋，像拉皮筋一样提前张拉；
2️⃣批量生产：一次支模多块桥板，绑钢筋、浇混凝土，效率超高；
3️⃣松手发力：等混凝土硬到75%强度，剪断钢筋，靠回弹力压紧桥板！
Construction three steps:
1️⃣Tabling and stretching: fix the reinforcement in the prefabrication plant with a special pedestal, and tension it in advance like pulling a leather band;
2️⃣Mass production: support the mold of many bridge plates at a time, tie the reinforcement and pour the concrete, the efficiency is super high;
3️⃣ Loosening force: wait for the concrete to harden to 75% strength, cut the rebar, and rely on the rebound force to press the bridge plate!
技术细节：
✔️ 钢筋必须带螺纹，增强与混凝土的“亲密接触”；
✔️ 粗钢筋端部要加钢筋网，防止“内力暴走”撑裂混凝土。
优点：工厂流水线作业，省钱省时！适合标准化小跨径板桥~
Technical details:
✔️ Reinforcing bars must be threaded to enhance “intimate contact” with the concrete;
✔️ The ends of thick reinforcement bars should be reinforced with steel mesh to prevent the “internal force from running out” and cracking the concrete.
Advantages: Factory assembly line operation, saving money and time! Suitable for standardized small-span slab bridges
