2.5 Bridge member
Participants must use rigid steels; that is, a cable or a wire is not allowed.
Bridges must consist of structural steel. The steel is defined as an iron alloy that is strongly attracted to the magnet.
The size of a bridge member must be less than 150mm×150mm×800mm. It means that one bridge member can be put in the box of 150mm×150mm×800mm volumn.(see also2.3)
A bridge member must be a rigid component during the construction and the loading tests. Hinged, telescoping members are prohibited. This prohibition includes members with parts that are intended to slide, rotate, deflect or bend relative to the member such as cams, sliding pins, springs, and snap-lock devices.
A member may consist of multiple parts rigidly joined together before timed construction begins. Those parts must remain rigidly joined throughout timed construction and in the completed bridge. If the bridge has ready-component bolts and nuts, it cannot be loosened throughout the timed construction, and those bolts and nuts must be colored to show that they are not fasteners.
2.6 Fastener
A fastener is a steel bolt that is not a part of a member, with at least one steel nut that is not part of a member. Diameter is not restricted.
The nuts in a fastener must match the bolt.
Nuts and bolts that connect the parts of a member but do not connect a member to other members are not considered to be fasteners.
Fasteners must NOT be colored. The original metallic surface condition must be kept in order to distinguish fasteners from a part of the member.
Washer is allowed to use as a part of fasteners; also, as a use of a spacer.
If participants use washers, the washers must not be welded or glued to the bolt head or the nut.
Tools for fasteners must be hand worked, not be electric assists including battery devices. Those tools, which are spanner, ratchet, and monkey wrench for example, must be prepared by participants themselves.
2.7 Member-to-member connection
During the construction works, each member must be connected by at least one fastener.
A couple of a bolt and a nut must match each other on its size.
A member shall be connected to other ones by combinations of bolts and nuts during timed construction. No bolts and nuts can be welded to members; also screwed connections are not allowed (Fig.2.5)