Special inspection is a very vague term, depending in the code or specifications. Some older codes even had a distinction between portland/lime and masonry cement for some stresses.
Some older "boiler plate" specs may require it even it is not necessary. There are people certified as qualified for special inspection if really required.
I have seen projects of numerous 20 story 6" block loadbearing masonry construction and the design engineer set up a inspection program that required sampling using video for inspecting a certain percentage of the cores scheduled for grouting. All units were certified and identified at the plant before delivery because 4 different strengths were used on the project of 10 buildings going up simultaneously. No grouting was permitted in the unreinforced cells (the engineer was a follower of Jim Amhrein and other masonry experts) that did not believe in relying on something that could not be controlled.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
The code (ACI 530) allows a higher value of stress for masonry design if the construction is inspected, as opposed to not inspected. That includes "special inspection" in accordance with the IBC.
I was aware of that since I was on the committee that wrote the fist few versions of ACI standard starting with ACI 530-02. ACI 530 followed the NCMA "green book" regarding concrete masonry for years in California until a comprehensive masonry code could be written. Most engineered masonry in the world is concrete masonry.
These type of documents have no legal importance until it is adopted by a legal authority or specified by the designer as a requirement. - Same as the ASTM standards for products, testing and procedures and in many cases to the items in an appendix for a specific item, like the ASTM C270 appendix note 1 that stresses the importance of workability as being a major in the construction process. They are, however very valuable reference even if they are not a legal document in a jurisdiction. Not all areas reference ACI or ASTM as a blanket specification.
The project I referenced earlier did use ACI and ASTM standards in many cases. When I asked the engineer what standard was used he said "We use your standards and codes in creating the specifications, but we use them better for this particular project". All of the pre-approval plant testing and site mortar and grout was done according to ASTM requirements and the general designed used ACI 530 as a reference for the design. Since the use of masonry is more advance in this country, the strict requirement to follow ACI 530 was not practical are justified if alternate systems could be used on major projects.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
To the best of my knowledge, I do not think the ACI 530 code permits 1/2 allowable stresses to be used for engineered masonry.
The Uniform Bldg Code (UBC) allowed use of 1/2 allowable stresses depending on f'm etc, when working stress design (WSD) was used. It did not permit use of 1/2 stresses for Strength Design; and when strength design was utilized, special inspections were required.
With the UBC-WSD approach, special inspections were not required when 1/2 allowable stresses were used- but special inspections were required for full allowable stresses. Currently, I do not think any jurisdiction allows the use of the UBC for new construction.
I do not have a copy of the UBC handy, but of the top of my head, you'd have to look at sub-sections in UBC 1701, 1706, and 1707 to find applicable provisions.
If you use ACI 530s allowable stress design or strength design, special inspections will be required.
What masonry design code does the jurisdiction allow?
