Case Study Title: Comparative Structural Analysis of Pratt and Howe Truss

Configurations Using RISA$-2$D

Objective: This project involves analyzing and comparing the structural performance of two classic truss designs$-$Pratt and Howe trusses$-$under identical loading conditions using RISA$2$D software. The goal is to identify the most efficient truss configuration based on factors such as material usage, deflection, internal forces, and overall stability, with a focus on the strength$-$to$-$weight ratio.

Background: The configuration of a truss plays a critical role in its structural performance. Compression members are often "reinforced" to prevent buckling. In this assignment, the Pratt and Howe truss designs will be compared to evaluate their performance and efficiency.

Details:

Loading Conditions:

Dead Load $($P$)$: $15$ kips

Live Load $($P$)$: $100$ kips

Material: Steel with a yield stress of $45$ ksi for tension members and critical stress for compression members: $24$ ksi

Tasks: a$.$ Structural Analysis Using RISA$-2$D:

Perform a comprehensive analysis of each truss, including:

Axial force diagrams

Diagrams showing reactions and member forces

Deflected shape of each truss

Use ASCE LRFD load combinations for the analysis.

b$.$ LRFD Axial Force Demand:

Calculate the LRFD axial force demand for each member.

Exclude the truss's self$-$weight from these calculations.

c$.$ Required Cross$-$Sectional Area:

Determine the required cross$-$sectional area for each member, assuming a minimum area of $1i{n}^2.$

$->$ d$.$ Tabulated Results:

Create a table summarizing the following:

Member forces, cross$-$sectional areas, member lengths, and member weights $($with a steel density of $490l\frac{b}{f}{t}^3)$

Calculate the total weight of each truss.

Determine which truss design is more efficient based on the strength$-$to$-$weight ratio and overall performance.

Provide conclusions and insights on the design comparisons.

Deliverables::

$->$ RISA Output to be included: Truss model with joint labels, member labels, and loads shown, data tables $($member forces, support reactions, deflections$),$ axial force diagram and deflected shapes $.$

$->$Reference list.

Note: Ensure the report is concise, with all relevant calculations and results clearly presented. $($ Please answer all the steps and include RISA Graphs and tables $)$

I really appreciate your help:$($