P E R F O R M A C E D
R
I
V
E
N
D
E
S
I
G
N
A
N
T
O
N
I
O
N
O
R
S
W
O
R
T
H
Y
A R G U M E N T
The undergraduate architecture curriculum at WSU currently relies on a traditional approach to design where students are encouraged to develop a conceptual narrative that serves as the guiding principle for subsequent aspects of the project. That concept is cultivated in response to a specific set of program and environmental considerations--a top down approach. Based on the capabilities and limitations of wood structural members I have developed a mutable system that, in aggregation, is capable of adapting to a range of programmatic and environmental constraints --A bottom up approach.
DOWEL OR BOLT ASSEMBLY
STEEL BRACKET
JOINERY
3” X 18” WOOD PLANK
PROTOTYPICAL SYSTEM EXPLODED AXON
CONCRETE FOOTING
R E S E A R C H
For this systems-based design methodology I utilized a bottom-up approach which sought to inform subsequent aspects of the design solution based on capabilities and limitations of wood as a construction material. This project evolved from an investigation into wood products for their intrinsic qualities.
ORTHOTROPIC NATURE n
Radial
Table 4–1. Elastic ratios for various approximately 12% moisture content
Tangential
Figure 4–1. Three principal axes of wood with Longitudinal respect to grain direction and growth rings. The orthotropic nature of wood means it has unique and independent
mechanical properties inaxis the directions three mutually perpendicular the tangential T isofperpendicular to the grain but tangent axes: longitudinal, radial, and tangential. to the growth rings. These axes are shown in Figure 4–1.
Elastic Properties Twelve constants (nine are independent) are needed to describe the elastic behavior of wood: three moduli of elasticity E, three moduli of rigidity G, and six Poisson’s ratios µ. The moduli of elasticity and Poisson’s ratios are related by expressions of the form µ ij Ei
=
µ ji Ej
,
i ≠ j i, j = L,R,T
DESIGN CONSIDERATIONS
re
i rD
e Fib
o cti
(4–1)
General relations between stress and strain for a homogeneous orthotropic material can be found in texts on anisotropic elasticity.
Modulus of Elasticity
Species
ET/EL
Ash, white Balsa Basswood Birch, yellow Cherry, black Cottonwood, eastern Mahogany, African Mahogany, Honduras Maple, sugar Maple, red Oak, red Oak, white Sweet gum Walnut, black Yellow-poplar
Hardwoods 0.080 0.125 0.015 0.046 0.027 0.066 0.050 0.078 0.086 0.197 0.047 0.083 0.050 0.111 0.064 0.107 0.065 0.132 0.067 0.140 0.082 0.154 0.072 0.163 0.050 0.115 0.056 0.106 0.043 0.092
Baldcypress Cedar, northern white Cedar, western red Douglas-fir Fir, subalpine Hemlock, western Larch, western Pine Loblolly Lodgepole Longleaf Pond Ponderosa Red Slash Sugar Western white Redwood Spruce, Sitka Spruce, Engelmann
ER/EL
Fb bending species a
GLR/EL
= extreme fiber stresss in
at
GLT/EL GRT/EL
Ft grain
= tension parallel to
0.109 0.077 — 0.054 0.037 = 0.005 Fv horizontal shear 0.056 0.046 — 0.074 0.068 0.017 0.147 0.097 — 0.076 0.052 — Fc compression 0.088 0.059 = 0.021 parallel to grain 0.066 0.086 0.028 0.111 0.063 — 0.133 0.074 — 0.089 0.081 — Fperp = compression perpendicular to grain 0.086 — — 0.089 0.061 0.021 0.085 0.062 0.021 0.075 0.069 0.011 E
= modulus of elasticity
Softwoods 0.039 0.084 0.081 0.183 0.055 0.081 0.050 0.068 0.039 0.102 0.031 0.058 0.065 0.079
0.063 0.210 0.087 0.064 0.070 0.038 0.063
0.054 0.187 0.086 0.078 0.058 0.032 0.069
0.007 0.015 0.005 0.007 0.006 0.003 0.007
0.078 0.068 0.055 0.041 0.083 0.044 0.045 0.087 0.038 0.089 0.043 0.059
0.082 0.049 0.071 0.050 0.138 0.096 0.055 0.124 0.052 0.066 0.064 0.124
0.081 0.046 0.060 0.045 0.115 0.081 0.053 0.113 0.048 0.077 0.061 0.120
0.013 0.005 0.012 0.009 0.017 0.011 0.010 0.019 0.005 0.011 0.003 0.010
0.113 0.102 0.102 0.071 0.122 0.088 0.074 0.131 0.078 0.087 0.078 0.128
a
EL may be approximated by increasing modulus of elasticity values in Table 4–3 by 10%.
Elasticity implies that deformations produced by low stress are completely recoverable after loads are removed. When loaded to higher stress levels, plastic deformation or failure This adjusted bending EL can be used to determine ER and ET occurs. The three moduli of elasticity, which are denoted by based on the ratios in Table 4–1. EL, ER, and ET, respectively, are the elastic moduli along the longitudinal, radial, and tangential axes of wood. These Poisson’s Ratio The development a parametric algorithm enabled quick exploration moduli areof usually obtained from compression tests; however, data forconfigurations ER and ET are not based extensive. valuesto of material of potential system onAverage a response When a member is loaded axially, the deformation perpenER and ET for samples from a few species are presented in dicular to the direction of the load is proportional to the attributes Table and 4–1 a set defined Regularity of the material asof ratios with Eparameters. L; the Poisson’s ratios are shown parallel to the direction of the load. The ratio of components means are suitable the logic deformation of in Table 4–2.they The elastic ratios, asfor wellapplication as the elasticto conthe transverse to axial strain is called Poisson’s ratio. The stants themselves, vary within and between species and with a ruled surface. The form of a simple rectangular plane was chosen Poisson’s ratios are denoted by µ LR, µ RL, µ LT, µ TL, µ RT, and moisture content and specific gravity. µ . The first letter of the subscript refers to direction of
D E V E LO PM E N T
LIGHT MODERATION
Variations identified in response to environmental and social performance requirements
VIEWS
as a constraining armature because it was perceived to be the most TR applied stress and the second letter to direction of lateral Thethe modulus of elasticity from receptive of variations to bedetermined applied to it.bending, EL, rather than from an axial test, may be the only modulus of elasticity available for a species. Average EL values obtained from bending tests are given in Tables 4–3 to 4–5. Representative coefficients of variation of EL determined with bending tests for clear wood are reported in Table 4–6. As tabulated, EL includes an effect of shear deflection; EL from bending can be increased by 10% to remove this effect approximately.
+
ELEMENT SPACING
GTH
LENGTH
LEN
4–2 AREA
ROTATION ANGLE
deformation. For example, µLR is the Poisson’s ratio for deformation along the radial axis caused by stress along the longitudinal axis. Average values of Poisson’s ratios for samples of a few species are given in Table 4–2. Values for µRL and µTL are less precisely determined than are those for the other Poisson’s ratios. Poisson’s ratios vary within and between species and are affected by moisture content and specific gravity.
AREA WIDTH
WIDTH
+ PROPORTIONS HELD CONSTANT STRUCTURAL EFFICIENCY
ADDITIVE PARAMETER PROGRESSION
OFFSET
PARAMETER VARIATIONS MATRIX
SHELTER
ACOUSTIC RESPONSE
DEPLOYMENT
The versatility of the system is demonstrated by three possible deployment schemes on three distinct sites across WSU and Pullman. Each are equally viable in terms of their architectural merit.
PERFORMANCE VENUE | Open-air Theater at Kimbrough
SOCIAL NODE | Nevada Street Pavilion
CULTURAL ICON | Downtown foot bridge
SYSTEM ADAPTATIONS
EXPERIENTIAL CONDITIONS
shelter
light moderation
views
acoustic response SITE DEPLOYMENTS
NORTH
P R O P O S A L
After demonstrating the system’s versatility and successful deployment as an academic exercise, I sought to test it’s effectiveness in a real-world setting with practical constraints and limitations. As an ideal candidate for this scenario, the Pullman Civic Trust is currently finalizing plans for a new footbridge to connect walking paths between Johnson Road and Bishop Boulevard near Fireside Grille and Crimson and Grey. In addition to the physical span, the system will bridge the gap between traditional values and new ideas in performance-driven design.
6
4
5
2
3
1
MAP KEY
PEDESTRIAN
1 VILLAGE CENTRE CINEMAS
VEHICULAR
2 FIRESIDE GRILLE
SITE PLAN
3 SUMMIT THERAPY 4 POOCH PARK 5 CRIMSON AND GREY 6 DENNY’S
SOUTH ELEVATION
WEST ELEVATION