K T
structures
CHALLENGES OF A BIKE TIRE To start to understand how loads function in real life, I analyzed a bike tire. I found that I could apply what I learned in steel design to analyze the spokes. I also found that prestressing explains how the spokes are able to work.
The steel rim for the bike resists the tension forces of the spokes. The rim would buckle about its weak axis, here the y axis.
Spokes are slender
Slenderness =
Le √(I/A)
The spokes are too long (Le) and are too thin-- the cross-sectional area is too small (A)
So what? Slender members buckle under compression, so to make this bike tire work, there must be no compression.
SOLUTIONS TO A BIKE TIRE- SPOKES
PRESTRESS LOADS
SERVICE LOADS
FINAL LOADS
The prestressing process involves adding tension loads equally around the bike tire. These loads must be larger than the largest service compression loads.
Normally, a bike tire will be under compression at the bottom and tension at the top.
Once these loads are combined, the large tension loads from the prestressing process cancel out the compression service loads.
SOLUTIONS TO A BIKE TIRE- RIM
PRESTRESS LOADS
SERVICE LOADS
FINAL LOADS
The prestressing process involves adding compression loads equally around the bike tire to counter the prestress tension loads from the spokes.
Normally, a bike tire’s rim will be under compression at the top and tension at the bottom.
Once these loads are combined, the large compression loads from the prestressing process cancel out the tension service loads.
SOLUTIONS TO A BIKE TIRE- SYSTEM
FRAME LOADS
SPOKE LOADS
EQUILIBRIUM
MADRID BARAJAS AIRPORT, T4 To better understand real life loads, we analyzed a building under various loads. I chose Madrid Barajas Airport’s T4 and studied the main beam under wind loads.
Architects: Estudio Lamela, Rogers Stirk Harbour + Partners Location: Barajas, 28042 Madrid, Spain Area: 1100000.0 m2 Project Year: 2005
Wind loads hit the curved roof and the glass façade. When we focus in on the roof, we can see that there are both axial and bending at work. The roof beam is under compression from the parallel force and under a moment under the perpendicular force.
1. WIND LOAD
2. COMPONENTS, ⟂ & ∥
3. ∥ COMPONENT (AXIAL)
4. ⟂ COMPONENT (BENDING)
P0
V0 M0
SLA-ibrary
For this urban mediathèquÊ, in Chicago, designed last spring, I focused on how to use structural elements to create dramatic forms. While it was a challenge to understand how to incorporate the cantilevers while keeping the main structural elements at the façade, by doing so, I was able to rationalize the form.
extrude
split
primary shapes
secondary shapes
connection
60’
45’
29’
13’
0’
60’
45’
29’
13’
0’
-15’
-31’
GRAFTING When designing this public use interpretive center at the Arboretum in Urbana last fall, I was interested in grafting different forms generated by various site lines. However, three volumes at different angles made it a challenge to design a structure. By separating the systems, I was able to use the structure to define the spatial qualities of the volumes.
Empirical Shapes
Grafting
Path
Carve
Trim
Roof Plan
Structural Plan
Floor Plan