Hot-rolled Stirrup

Updated: 2026-07-19

Overview

Hot-rolled national standard stirrups are cold-bent steel bars used as transverse reinforcement in concrete structures. Manufactured under China's GB/T 1499.2-2018 standard, they play a critical role in earthquake-resistant construction by providing ductility and shear capacity. These stirrups are typically produced from low-carbon or low-alloy steel through controlled hot-rolling processes followed by precise bending to specified geometries. The standardized production ensures consistent mechanical properties and dimensional accuracy, making them preferred over site-fabricated alternatives in large-scale construction projects. Their use significantly improves construction efficiency while maintaining structural safety margins.

Structure and Working Principle

Standard stirrups feature closed rectangular or polygonal shapes with precise bend angles (usually 135° hooks) to effectively confine longitudinal rebars. The hot-rolling process creates a natural ribbed surface that enhances bonding with concrete. When subjected to seismic or shear forces, the stirrup's geometry prevents buckling of vertical bars while resisting diagonal tension cracks. Material selection follows strict yield strength requirements (335MPa or 400MPa grades) to ensure plastic deformation occurs only after concrete cracking, allowing controlled energy dissipation. The continuous production process eliminates weak points at welding joints, unlike fabricated alternatives.

Key Features

These stirrups exhibit superior dimensional consistency with tolerances within ±1mm for critical dimensions. The hot-rolled surface texture provides 20-30% better bond strength compared to smooth bars. Standardized bending radii (≥2.5d for HRB335, ≥3d for HRB400) prevent stress concentrations that could cause premature failure. Quality assurance includes mandatory stress-relief treatment after bending to maintain mechanical properties. Batch testing verifies elongation (≥16% for HRB335, ≥14% for HRB400) and cold bending performance. Anti-rust coatings (optional) extend shelf life at construction sites.

Application Areas

Primarily used in cast-in-place concrete structures for high-rise buildings, bridges, and underground works where seismic performance is critical. Standard stirrups are specified in beam-column joints, shear walls, and foundation tie beams. Their pre-formed geometry is particularly valuable in prefabricated construction for rapid assembly. Special applications include nuclear facilities and offshore structures where consistent quality is paramount. Modified versions with increased leg length serve as lateral ties in large cross-section columns. The construction industry increasingly adopts these components for BIM-compatible standardized detailing.

Maintenance and Precautions

Store stirrups on elevated platforms with waterproof covers to prevent rust formation. Surface rust (if occurring) must be removed by wire brushing before concrete pouring. Avoid impact damage during handling that could create microcracks at bend points. Regular inspection should verify absence of surface cracks, especially after long storage periods. For seismic zones, conduct additional sampling tests if storage exceeds 6 months. Construction teams must follow spacing requirements strictly—typically 100-200mm in critical zones per GB 50011 seismic code.

B2B Procurement Guide

Source from mills with GB/T 19001 certification and valid production licenses. Require mill test certificates showing chemical composition (C≤0.25%, S/P≤0.045%) and mechanical properties. For large projects, conduct factory audits assessing bending equipment calibration and quality control processes. Order quantities should account for 3-5% cutting waste during construction. Consider regional logistics—stirrups are typically shipped in bundled packs (2-3 tons per bundle) with plastic strapping. Negotiate pricing based on annual volume commitments, with tiered discounts above 500-ton thresholds. Just-in-time delivery requires 15-30 days lead time during peak seasons.