Step 5 – Lateral Capacity Vickars（步骤5 - Vickars横向能力）.pdfVIP

Step 5 – Lateral Capacity Introduction The primary function of a deep foundation is to resist axial loads. In some cases, they will be subjected to horizontal, or lateral loads. Lateral loads may be from wind, seismic events, live loads, water flow, etc. The resistance to lateral loads is in part a function of the near surface soil type and strength, and the effective projected area of the structure bearing against these soils. This section of the design manual presents a summarized description of the methods and procedures available to determine the lateral capacity of helical screw foundations in soil. The analysis of deep foundations under lateral loading is complicated because the soil reaction (resistance) at any point along the shaft is a function of the deflection, which in turn is dependent on the soil resistance. Therefore, solving for the response of a deep foundation under lateral loading is one type of soil-structure- interaction problem best suited for numerical methods on a desktop computer. Lateral Resistance – Methods Used It is obvious that helical screw foundations have slender shafts – which offer limited resistance to lateral loads that are applied perpendicular to its shaft. However, a large number of load tests have validated the concept that vertical pile foundations are capable of resisting lateral loads via shear and bending. Two commonly used methods to analyze the lateral capacity of pile foundations in soil is the finite difference method and the “Broms” method as outlined by Bengt B. Broms (1963). Figure 5.1a Figure 5.1b Figure 5.1c Shaft Resistance Passive Earth Pressure Resistance Battered Piles Enlarged Shaft Grade Beam Pile Cap Battered Piles Section