How do anchor bolts affect their overall performance in bearing tensile, shear, and bending moments?
Publish Time: 2026-02-19
As key mechanical connectors linking the superstructure steel to the concrete foundation, the performance of anchor bolts directly determines the safety of the entire structural system. Under complex wind loads, seismic action, and dynamic loads from equipment, anchor bolts must simultaneously withstand the combined effects of tensile, shear, and bending moments. Insufficient performance in any single area can lead to connection failure.1. Factors Affecting Tensile PerformanceThe tensile performance of anchor bolts primarily depends on material strength, effective anchorage depth, and the strength of the concrete foundation. Higher steel strength grades result in greater tensile bearing capacity, but this must be matched with the concrete strength to avoid cone-shaped failure of the concrete. Anchorage depth directly affects the tensile force transmission path; insufficient embedment depth leads to pull-out failure, while excessive depth results in material waste. Furthermore, the anchor bolt diameter, thread precision, and preload application method also affect the uniformity of tensile force distribution; insufficient preload reduces connection stiffness, while excessive preload may cause steel yielding.2. Factors Affecting Shear PerformanceShear bearing capacity is closely related to the shear cross-section of anchor bolts, the distance to the concrete edge, and the arrangement of anchor groups. Larger anchor bolt diameters result in larger shear cross-sections, but sufficient concrete edge distance must be considered; otherwise, edge splitting failure is likely. In an anchor group system, insufficient anchor bolt spacing can lead to stress superposition, reducing overall shear capacity. Installation accuracy is also crucial; anchor bolt tilting can cause shear force eccentricity, generating additional bending moments. For post-anchored anchor bolts, the shear performance of the adhesive or mechanical locking key must be considered to ensure effective shear force transfer to the concrete substrate.3. Factors Affecting Bending Moment PerformanceBending moments are typically caused by eccentric loads or structural overturning moments, placing higher demands on anchor bolt connections. Bending moments create tension-compression differences within the anchor bolt group, with one side of the anchor bolts under tension and the other under compression, forming a couple to resist overturning. The arrangement of the anchor bolt group directly affects bending resistance; increasing the anchor bolt spacing increases the lever arm length and enhances bending resistance. The stiffness of the base plate is also crucial; insufficient stiffness can lead to base plate deformation and uneven stress on anchor bolts. Furthermore, anchor bolt preload can enhance joint stiffness, reduce relative displacement under bending moment, and improve overturning stability.4. Synergistic Effect of Comprehensive PerformanceIn actual working conditions, tension, shear, and bending moment often act simultaneously, forming a complex stress state. The comprehensive performance of anchor bolts is not a simple superposition of these three capabilities, but rather a relationship of mutual influence and constraint. Under high tension, the shear capacity of anchor bolts will decrease; under large bending moment, some anchor bolts may prematurely yield. Therefore, interaction formulas must be used during design to verify that there is still sufficient safety margin under complex loads. Appropriate preload application can improve the distribution of the three forces and enhance overall connection performance.The comprehensive performance of anchor bolts in terms of tension, shear, and bending moment is the result of multiple factors acting together, involving the entire life cycle of materials, design, construction, and maintenance. Only through scientific selection and calculation, precise construction control, and rigorous quality testing can anchor bolts achieve "strong anchoring" under complex loads, ensuring that the upper steel structure and concrete foundation form a rigid whole, and providing a solid guarantee for the safety and stability of the entire structural system.
