Discussion: View Thread

Despite increasing scale and scope of mass timber construction, we are still relying heavily on steel and concrete for lateral load resistance in wood buildings.  Timber braced frames have now been implemented in contemporary buildings and have strong historical precedent.  One system that I haven't seen discussed is a mass timber moment frame.  Perhaps there is good reason for this, but let's entertain the thought.  There are certainly instances where architects might want the openness of a portal frame in timber.  Do you think a timber moment frame is possible?  What are some technical concerns that would need to be addressed?

Here are a couple that come to mind:

 - Connection slip amplified over the depth of a beam or column could result in large rotations before engaging an attached member.  Anyone who's checked story drift on a light-frame shearwall with an unfavorable aspect ratio knows NDS can be very punishing in these applications.
 - Orthotropic properties could cause issues transferring moment between horizontal and vertical frame members. - Long-term cross-grain shrinkage could result in loss of restraint as bearing surfaces which are initially flush pull away.  Perhaps some sort of take-up device could be developed to prevent this?

Eager to hear everyone's thoughts!

Despite increasing scale and scope of mass timber construction, we are still relying heavily on steel and concrete for lateral load resistance in wood buildings.  Timber braced frames have now been implemented in contemporary buildings and have strong historical precedent.  One system that I haven't seen discussed is a mass timber moment frame.  Perhaps there is good reason for this, but let's entertain the thought.  There are certainly instances where architects might want the openness of a portal frame in timber.  Do you think a timber moment frame is possible?  What are some technical concerns that would need to be addressed?

Here are a couple that come to mind:

 - Connection slip amplified over the depth of a beam or column could result in large rotations before engaging an attached member.  Anyone who's checked story drift on a light-frame shearwall with an unfavorable aspect ratio knows NDS can be very punishing in these applications.
 - Orthotropic properties could cause issues transferring moment between horizontal and vertical frame members. - Long-term cross-grain shrinkage could result in loss of restraint as bearing surfaces which are initially flush pull away.  Perhaps some sort of take-up device could be developed to prevent this?

Eager to hear everyone's thoughts!

Despite increasing scale and scope of mass timber construction, we are still relying heavily on steel and concrete for lateral load resistance in wood buildings.  Timber braced frames have now been implemented in contemporary buildings and have strong historical precedent.  One system that I haven't seen discussed is a mass timber moment frame.  Perhaps there is good reason for this, but let's entertain the thought.  There are certainly instances where architects might want the openness of a portal frame in timber.  Do you think a timber moment frame is possible?  What are some technical concerns that would need to be addressed?

Here are a couple that come to mind:

 - Connection slip amplified over the depth of a beam or column could result in large rotations before engaging an attached member.  Anyone who's checked story drift on a light-frame shearwall with an unfavorable aspect ratio knows NDS can be very punishing in these applications.
 - Orthotropic properties could cause issues transferring moment between horizontal and vertical frame members. - Long-term cross-grain shrinkage could result in loss of restraint as bearing surfaces which are initially flush pull away.  Perhaps some sort of take-up device could be developed to prevent this?

Eager to hear everyone's thoughts!