Masonry Magazine October 1976 Page. 7
(d) It provides an indigenous fire-proofing system due to its noncombustible construction characteristics.
(e) Durable system for buildings, such as barracks, which are subject to constant use.
(f) Minimum maintenance even with considerable abuse. The anticipated tenure of usage far exceeds the 25 year requirements of all government buildings with low maintenance costs during its life span. All interior and exterior masonry walls were left exposed with a paint finish.
Ramada Inn Convention Center Hotel, Dallas, Texas
Reinforced concrete block loadbearing walls and concrete floor slabs provide the structural system for the Ramada Inn Convention Center Hotel.
The hotel is located in downtown Dallas, just 223 steps away from the Convention Center. The most dramatic part of the facility is the roof-top restaurant, club and meeting rooms for which the entire skyline of downtown Dallas provides the setting.
The structural system consists of reinforced concrete block loadbearing walls and concrete floor slabs poured in place using flying forms.
Comparing earthquake (seismic) design requirements to those found in other parts of the country where wind governs, I can best illustrate the differences by comparing the masonry requirements we had in the Ramada Inn, to those of the west coast. In Texas, as in most of the country, high stress block units are not required. Grade A, standard 8-inch lightweight concrete pilaster block normally produced in Dallas carry the loads for 12 stories. These average 2,000 psi on the net section. In California these units could be used to 5 stories only. However, preliminary tests of prisms and prism tests as the building progressed were made for quality control purposes. Continuous special inspection and individual tests of 2,000 psi grout, mortar and the block were also made in accordance with the Dallas Code (1968 UBC).
Only part of the reduced requirements for higher stresses can be attributed to building shape, the rest by lighter loads due to wind. If one compares floor plans of the Town & Country and the Convention Center Ramada Inn, it can be seen that the Ramada Inn has a modified square plan, with rooms on each side of a central core and that the Ramada has three times the building depth in plan than one-room-wide Town and Country. This produces a considerable amount of walls that serve to brace the building against the wind. Hotel room end walls of the Ramada are completely glass enclosed, which is quite a daring trick in California, although this type of plan is most conductive to this openness.
Other major differences in this and our other Texas projects are the exterior treatment, due to weather conditions, and the requirements for slight modification of normal Texas units to accommodate the reinforcing steel.
The standard 8" x 8" x 16" unit manufactured in California is a square edge closed end unit with two cells. This block has been used for years in California, rather than the unit with a slight recess on the ends (called engineered block), due to the steel and grouting required for seismic considerations. The engineered block cells do not line up vertically, thus making this type of unit difficult to grout. To assume proper vertical joints and grouting continually, we used standard pilaster blocks in Dallas at no additional costs.
Other modifications were to have 1½ inch depressions at the top of cells and ends to receive horizontal steel. We also have open end blocks (1 end open), double open end (H-block) and sometimes use U-blocks for exterior corners, in standard and bond beam shapes, developed so the mason can just slip the block around the vertical steel. In California these are all standard shapes. In Texas some of the units were manufactured for the job and others saw cut on the job by the mason. Holes for electrical outlets are either saw cut on the job or manufacturers make electrical units with blockouts to receive J-boxes. Where 3-hour walls are required, a thicker face shell was manufactured.
To make it clear to the mason and block manufacturer, we provided isometrics of the block on the structural drawings as well as specified the shapes and standards for manufacture in order to make construction easier.
After much discussion with masons, manufacturers and observation of local projects, it was decided to have all exterior concrete block walls veneered with face brick as they are laid up, to act as waterproofiing, decoration and added insulation. In Southern California and Hawaii we (Please turn page)
masonry
October, 1976
7
About The Author
John R. Mock, President, Handrick & Mock Architects, San Diego, Calif., is one of North America's leading authorities on loadbearing masonry structures. His has designed many outstanding loadbearing structures in recent years and has several more in the planning stage. Many will remember him for his excellent presentation at the 76 MCAA Convention held at the Town & Country Hotel, San Diego.