Design a rectangular beam continuous over three spans as shown in the accompanying figure. The live load is 2.4 kips/ft, and the superimposed dead load is 1.6 kips/ft in addition to the beam weight.
Supports are 16″ wide. Assume fic = 4,000 psi, and f1= 60,000 psi.
a) Is ACI simplified method of analysis for continuous beams applicable to this beam? In any case find the critical moments per ACI Approximate method.
b) Using an analysis software, draw influence lines for moment at the center of each span and at the interior support. Employing these influence lines, determine the maximum positive and negative moments at these sections for the factored load. Draw clear diagrams of the loading for each case (i.e., load pattern).
Compare these moments (elastic analysis) to those of part (a).
c) Design a rectangular section for the entire beam using the moments from part (b).
d) Draw influence lines for shear at critical sections and determine the maximum shear at each section using only full-span loading.
Design the shear reinforcements using U stirrups of #3 bars if possible. e) Analyze and design the beam using Robot within Rivet (strongly recommended) or program of your choice and compare the results to your hand solution (e.g., moment envelop from your computer model vs. moments from part (b).
