Bamboo open web joist

Abstract

Bamboo open web joists are disclosed herein. One aspect of the invention is directed toward an open web joist design comprising a plurality of structural components made from compressed bamboo segments. Some of the structural components are formed into arched shapes. The structural components are built into a built-up beam comprising end members and span members comprising a frame, with a plurality of arched components positioned within the frame. Several fastener plates comprising a sheet with integral spikes are pressed into the structural components to hold the members together. The arched members define an open space in the built-up joist, through which mechanical components, electrical components, ducting, and other materials can pass.

1 . A bamboo joist, comprising:
 a pair of end members;   a first span member and a second span member extending between the pair of end members, wherein the end members and the span members define a frame;   a plurality of arched members positioned in the frame, individual arched members having a first leg, a second leg, and an arch portion between the first and second leg, wherein the first and second legs of the arched members are positioned against the first span member, and the arch portion of the arched members contacts the second span member; and   a plurality of fastener plates, individual fastener plates comprising a plate and a plurality of spikes extending from the plate, wherein the spikes are pressed into the members at corners of the frame where the arched members contact the span members, and where the arched members contact the end members, the fastener plates being configured to fasten the arched members in the frame.   
     
     
         2 . The bamboo joist of  claim 1  wherein the end members, the span members, and the arched members are formed by:
 forming a plurality of layers comprising dried and glue-coated bamboo segments; 
 stacking the plurality of layers with adjacent layers being positioned with bamboo fibers extending in different directions; and 
 compressing and bonding the layers together until the layers form a single integral structure. 
 
     
     
         3 . The bamboo joist of  claim 1  wherein the end members, the span members, and the arched members are formed by:
 forming laminated bamboo strands; 
 placing the strands in a random stacked parallel strips; and 
 fusing the strips together using pressure and adhesives between the strips. 
 
     
     
         4 . The bamboo joist of  claim 1  wherein the arch portion, the first leg, and the second legs of the arched members comprise an arch of substantially uniform radius. 
     
     
         5 . The bamboo joist of  claim 1  wherein the first and second legs are generally straight. 
     
     
         6 . The bamboo joist of  claim 1  wherein the spikes are integrally formed with the fastener plate. 
     
     
         7 . The bamboo joist of  claim 1  wherein the frame comprises a front side and a back side, and wherein the fastening plates are positioned on at least one of the front side and the back side. 
     
     
         8 . The bamboo joist of  claim 1  wherein the arched members are formed by placing a bamboo structural component in a mold and applying at least one of heat, pressure, and moisture to the bamboo structural component in the mold. 
     
     
         9 . The bamboo joist of  claim 1  wherein the arch portion comprises a generally straight middle portion that is configured to contact the second span member. 
     
     
         10 . A built-up structural beam, comprising:
 a plurality of curved members, each having a first end, a second end, a convex side, and a concave side;   a lower member extending substantially the length of the structural beam, the plurality of curved members being positioned with the concave side facing the lower member and the first and second ends contacting the lower member;   an upper member extending substantially the length of the structural beam, the convex side of the curved members contacting the upper member;   a first end member and a second end member positioned adjacent to the upper and lower members and adjacent to one of the plurality of curved members; and   a plurality of fastener plates comprising a sheet of material with a plurality of spikes extending from the sheet, wherein the spikes are pressed into the built-up structural beam to fasten members together;   wherein the curved members, the upper and lower members, and the end member are formed of bonded bamboo segments.   
     
     
         11 . The built-up structural beam of  claim 10  wherein the curved members are semi-circular sections with substantially uniform radius of curvature. 
     
     
         12 . The built-up structural beam of  claim 10  wherein the curved members, the upper and lower members, and the end members are formed by:
 drying bamboo segments; 
 coating the bamboo segments with glue; 
 arranging the segments into layers with bamboo fibers extending in a uniform direction; 
 stacking the layers such that bamboo fibers in consecutive layers extend in substantially different directions; 
 compressing the layers together into an integral structure. 
 
     
     
         13 . The built-up structural beam of  claim 12  wherein the bamboo segments in the layers are randomly arranged. 
     
     
         14 . The built-up structural beam of  claim 10  wherein the curved members comprise a first straight section, a first elbow, a second straight section, a second elbow, and a third straight section, wherein the second straight section is configured to contact the upper member and to extend substantially parallel to the upper member. 
     
     
         15 . The built-up structural beam of  claim 14  wherein the first and second elbows comprise a bend of less than 90 degrees in the curved member. 
     
     
         16 . The built-up structural beam of  claim 10  wherein the end members are configured to be trimmed to fit without interfering with the curved members. 
     
     
         17 . A method of forming an open-web bamboo joist, comprising:
 forming a plurality of bamboo components comprising bamboo span components, bamboo end components, and curved bamboo components;   forming a rectangular frame by connecting the bamboo span components to the bamboo end components;   placing the curved bamboo components in the frame such that a convex side of the curved bamboo components faces toward one of the bamboo span components, ends of the curved bamboo components abutting at least one of another curved bamboo component or a bamboo end component; and   fastening the bamboo span components, the bamboo end components, and the curved bamboo components together by pressing a fastener plate having spikes into the bamboo components.   
     
     
         18 . The method of  claim 17  wherein forming the plurality of bamboo components comprises:
 cutting bamboo into bamboo segments; 
 drying the bamboo segments; 
 coating the segments with glue; 
 placing the segments into layers with bamboo fibers extending substantially in a uniform direction throughout the layer; 
 stacking the layers; 
 compressing the layers together into a solid structure. 
 
     
     
         19 . The method of  claim 18  wherein the bamboo components comprise three or more layers of bamboo segments. 
     
     
         20 . The method of  claim 17 , further comprising:
 removing husk, outer nodes, and inner membrane from the bamboo; and   arranging the layers such that each successive layer contains bamboo fibers aligned in a direction different than a previous layer.   
     
     
         21 . The method of  claim 17  wherein forming the curved bamboo component comprises placing a straight bamboo component in a mold with a shape and applying at least one of heat, pressure, and moisture to the straight bamboo component until the straight bamboo component takes the shape of the mold and the glue is cured. 
     
     
         22 . The method of  claim 21  wherein the shape includes a first elongated portion, a first elbow, a second elongated portion, a second elbow, and a third elongated portion.