A force that tends to shear the left portion of the beam upward with respect to the right portion is said to produce a positive shearing force. A force that tends to bend the beam downward is said to produce a positive bending moment. The customary sign conventions for shearing force and bending moment are represented by the figures below. Each geometry item can be auto-meshed to generate a mesh.
The slope of the moment diagram at a given point is the shear at that point.The area of the shear diagram to the left or to the right of the section is equal to the moment at that section.The following are some important properties of shear and moment diagrams: A similar effect occurs when output-station spacing is fairly large for moment-diagram plots.Thus, the rate of change of the shearing force with respect to x is equal to the load or the slope of the shear diagram at a given point equals the load at that point. Influence-line frequently asked questions are listed as follows: Why is the influence line not displayed as a smooth line?Īnswer: Influence lines will appear piecewise linear when discretization is more coarse.
#RISA 3D MODIFY AREA LOAD SERIES#
To use such a vehicle in step-by-step moving-load analysis, the uniform load would need to be approximated and modeled using a series of equivalent point loads. Step-by-step frequently asked questions are listed as follows: Why does step-by-step moving-load analysis not run when the vehicle is defined using a uniform load?Īnswer: Vehicles defined using a uniform load may only be used during influence-based moving-load analysis. Why are zero results generated for a bridge object which is updated as a solid model?Īnswer: Analysis > Bridge Response > Moving Load Case Results Saved > Section Cuts must be selected for solid models, while it is not necessary for frame and shell models. See Deformed shape for moving load analysis. Why does deformed configuration from moving-load analysis not look correct?
How are unit loads distributed from lane-load points to model joints?Īnswer: For response, please see the Influence-based moving-load analysis implementation and Lane-load point connection articles. For additional details, please see the Influence-based moving-load analysis implementation article. Influence-based frequently asked questions are listed as follows: How is the load from each truck axle distributed over shell objects?Īnswer: During influence-based moving-load analysis, an interpolated influence surface determines the effect of loading from each truck axle.
Why are my bridge objects returning zero force during moving-load analysis?Īnswer: The request for saving section forces should be made such that bridge objects return the proper response during moving-load analysis. To obtain Multi-step Static response for a vehicle which may travel in either direction, results from Forward and Backward patterns may be enveloped.For step-by-step moving-load analysis, in which Multi-step Static is specified for load-case type, Forward or Backward vehicle direction may be specified on the Multi-Step Bridge Live Load Pattern Generation form.For influence-based moving-load analysis, in which Moving Load is specified for load-case type, the vehicle automatically moves in two directions.When a vehicle is defined, how are two directions specified for its path of motion?Īnswer: Depending upon analysis type, direction may be defined as follows: How is the speed of a moving truck changed?Īnswer: For step-by-step moving-load analysis, once a load pattern of Bridge Live type is defined, select Modify Bridge Load to access the Multi-Step Bridge Live Load Pattern Generation form in which the speed of a moving truck may be specified. Braking, acceleration and centrifugal horizontal loads can be defined. General frequently asked questions are listed as follows: How are transverse moving loads applied?Īnswer: Transverse (horizontal) moving loads are available since CSiBridge V17.2.0.