Hi Dan / Kumar - are you the same person ? you ask the same question, but many years apart ... if you are the same person, you are very patient !!!
My thoughts on your problem are based on my experience with building my dome ( Australian Dome Shed )- for which the side door is exactly what you are looking to achieve ( although my dome is frameless and therefore more of a shell ).
If you drop a verticle strut from each of the two ends of the top edge of the proposed opening, you have the makings of a proper door frame ( I assume to be approximately 5 ft wide and 10 ft high ). Then you will need to connect the two incomplete verticies to the midpoint of their closest verticle member ( the door jambs ) - this will give you two half triangles either side of the door frame to fill in. How pure you get your dome depends on how you connect those last members to the door jambs ... and that can be worked out once you have formed the opening.
For my dome, I used 40 mm x 40 mm x 4mm square steel tubing for the door jambs - welded to the door head of the same material ... but you already have a strut at the top of the opening and that should be enough. The door jamb material needs to be stronger than your normal strut because loads are being applied to their midpoints.
My dome did not deflect without the support of the door frame - ie. you should be able to just remove the struts to create the opening and then fit the door frame ... but it would be safer to use temporary bracing struts during the works.
Can you post a photo of your dome for us to see ?
Linton

I love these beautiful sites like this, many useful and nice, especially liked this article... I would wait for the new, nice updates on your site...

We have a 40foot 5v 3/4 inch conduit dome that we'd like to remove a section from for a door. The opening amounts to an elongated hexagon two courses up from the bottom opposite one pentagon. We're wondering if you have to match the geometry of door frame with single piece of reinforced steel or whether there's a simpler system that will work. Any input would be greatly helpful...

A door frame of some design is required. No way around it. As Bucky might say, can't let in infinity.

705.04 Each of the barrel's tension hoops represents a separately operating, exclusively tensional circle with its plane parallel to, and remote from, the planes of the other, only separately acting, barrel hoops. The tension bands do not touch one another. The tension bands are only parallel to one another and act only at 90 degrees against the staves, which are also only parallel to one another. Neither the staves nor the tension hoops cross one another in such a manner as to provide intertriangulation and its concomitant structural self-stabilization. In fact, they both let infinity into the system to disintegrate it between the only parallel staves and hoops whose separate parts reach forever separately only toward infinity.
705.05 If we take a blowtorch and bum out one of the wooden staves, the whole barrel collapses because infinity floods in to provide enough space between the staves for their arch to be breached and thus collapse disintegratively. What the blowtorch does is to let infinity__or the nothingness of Universe__into the system to intrude between the discontinuous and previously only contiguously crowded together, exclusively compressional members of the system.

http://www.rwgrayprojects.com/synergetics/s07/p0000.html

Read about infinity here.

Pls advise if you got an answer to this question. I'm very much interested in knowing the solution.

Regards,

bibo