‘bending bridges’ shapes plywood into double curvature pedestrian bridge in mexico

the project ‘bending bridges’ developed a double-layered construction system for a free-standing load bearing lightweight wooden structure. the pedestrian bridge was achieved through global double curvature, and a local active bending principle. the bridge exploits the elastic bending capacity of standard thin plywood and proposes an innovative construction form for lightweight structures. the project was created by a group of students and research professors of the centro de estudios superiores de diseño de monterrey in mexico. 

images © héctor pineda images courtesy of centro de estudios superiores de diseño de monterrey

project view

the design explores structurally complex curved forms that fulfill both architectural and structural constraints. the arch and the surface curvature were designed and optimized though computational structural analysis to carry loads directly to the foundation. this allows the bridge to withstand the weight of 5 people crossing over it while guaranteeing structural integrity with minimum displacement.

double curvature

the bridge’s global design has been driven by a spline-like curve, which allows to have an optimal distribution of forces. this feature enables minimum bridge inclinations on the bottom and top of the arch. in order to allow the assembly of double-curved geometries, a set of numbered strip patterns were introduced in the design process, generating a series of unique curvilinear unrollable members. the strategy of segmenting the bridge’s assembly allowed it to be built section by section from both ends towards the centre. The double-layer system was integrated to such process, which allowed the curvature of each section to fix in place without springback, while maintaining internal stress forces that become a stiffening factor.

an efficient wood steaming method was developed to explore heat and humidity as material treatment. the system allows to hygroscopically enhance the material bending properties enabling the assembly of a wider range of bent geometries. this makes the on-site manipulation of the material much easier. the steaming system includes a wooden box, a gas tank, a custom stove, sealed pots, stretchable aluminum pipes and a hygrometer. all the bridge members and connections are unique, digitally fabricated with cnc machines, computationally designed in the 3D model and then materialized through cnc milling codes.

long spanning pedestrian bridge

the entire construction process, programmed fabrication and assembly stages happen in parallel. although the development of the construction system took almost a year, the project’s fabrication and construction phases took only 4 weeks. the final research result has a constant cross section of 9 cm, a span of 12m and a maximum height of 2.5m. the bridge presents exciting findings for the advancement of lightweight material applications and for structual performance for large span construction.

foundation detail

double layer close-up

the bridge displays innovative material performance

load bearing structure

active bending

lightweight structure enables up to five people

technical drawings courtesy of centro de estudios superiores de diseño de monterrey

methods

computational model

construction system

project info:

institution: centro de estudios superiores de diseño de monterrey cedim
course: strip strategies studio 2018
academic director: david durán
professor: djordje stanojevic
foundation advisor: jorge a. jiménez
structural consultant: kenryo takahashi
system development, fabrication and construction: linda g. carmona, grecia c. cortes, ivan a. durán, mónica v. garcía, josé l. garcía, a. karen garza, isaac e. garza, patricia gutiérrez, denise llano, frania y. logan, sergio martinez, carlos a. muñoz, alberto ortega, j. adrián reyna, ma. fernanda ruíz and jesús e. villalobos.
with the support of: gabriela garcía, i. fabrizio hernandez, christian ortiz and regina zermeño.
sponsors: stm robotics, ezequiel cadena bernal madera, aceros fercom rar – s.a. de c.v., osel, herramientas, birlos y tornillos, coragui rental – s.a. de c.v.., montajes y estructuras delta, andamios monterrey
photography: héctor pineda images courtesy of centro de estudios superiores de diseño de monterrey cedim