Distributed load

Definition

A distributed load is a type of loading that spreads over a certain length of a structural element, rather than being concentrated at a single point. This load is typically measured in force per unit length, like pounds per foot or newtons per meter, and it plays a significant role in the behavior of structures by influencing how forces are distributed and how members respond.

5 Must Know Facts For Your Next Test

1. Distributed loads can be uniform, where the load intensity is constant along the length, or varying, where the load intensity changes across the length.
2. When analyzing structures with distributed loads, engineers often convert these loads into equivalent point loads for simpler calculations.
3. Distributed loads affect the internal shear and moment diagrams, impacting how forces are transmitted through structural members.
4. The calculation of reactions at supports due to distributed loads involves integrating the load function over the length of the beam or truss member.
5. In beams, distributed loads can lead to bending moments that vary along the length of the member, requiring careful analysis for safe design.

Review Questions

• How does a distributed load affect the internal force diagrams of a beam compared to a point load?
  • A distributed load creates continuous shear and bending moments along its length, leading to varying internal forces within the beam. In contrast, a point load generates localized effects at its application point, resulting in sudden changes in shear and moment. When analyzing beams under distributed loads, engineers must consider these variations to accurately predict deflection and ensure structural integrity.
• Explain how distributed loads influence the stability and determinacy of truss structures.
  • In truss structures, distributed loads can affect stability by altering the load paths and introducing additional internal forces in members. The presence of distributed loads may lead to redundant members, complicating determinate analyses. Engineers need to account for these effects when classifying trusses and ensuring they meet stability criteria, often requiring methods like joint equilibrium to analyze member forces accurately.
• Evaluate how the presence of distributed loads impacts the deflection calculations for continuous beams compared to simply supported beams.
  • In continuous beams subjected to distributed loads, deflection calculations become more complex due to the interaction between spans and support conditions. The continuous nature allows for redistribution of internal forces and moments, resulting in less deflection than an equivalent simply supported beam under similar loading. Methods such as the moment-area or conjugate beam approaches help engineers analyze these scenarios effectively to ensure compliance with serviceability criteria.

Related terms

point load: A point load is a concentrated force applied at a single location on a structural element, which can cause localized stress and deformation.

load combination: Load combination refers to the practice of considering multiple types of loads acting simultaneously on a structure, which helps ensure safety and performance under various conditions.

shear force: Shear force is the internal force in a structural member that resists sliding or shearing between different sections of the member due to external loads.