Japanese Box-frame type precast reinforced concrete construction of one to five-storied multiple houses has been technically improved by the peculiarity to the earthquake country and it has been obtained excellent results. It is the time to be considered to apply this construction method to multi-storied prefabricated houses.
As proceeding the research of this construction method into multistories, it has been pointed out the design and execution problems to the present Joint method, and various inconsistent idea with the stress-conveyance method.
For this reason, with a series of the research that we have been engaged in from 1966, I point out not only the questions on the mechanical behavior of this construction method, but also development research of the improved direct type Dry Joint.

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Recently, by establishing the structural models for concrete as a two-phase material, a number of formulae developed for the theoretical prediction of the elastic modulus of concrete from the elastic moduli and the volume concentrations of the constituents have been proposed.
However, the conformity between values of elastic modulus of concrete calculated from these theoretical formulae and values determined experimentally has not satisfactorily investigated.
In this report, the typical structural models proposed now and the theoretical formulae obtained on the basis of them are examined.
Furthermore, the elastic modulus of concrete made with the aggregates having widely different elastic moduli are determined experimentally, and it is evidenced that Hashin-Hansen's equation is in satisfactory agreement with the experimental values.

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The thesis illustrates the results of construction of steel lined penstock for Okutataragi scheme in the Kansai Electric Power Co.. The inclined penstock is 530 m in length and is designed as such the hydraulic pressure as to be submitted partially to its periphery rock.
The author demonstrates that the rate of internal pressure acting on rock is improved on integration by using newly-developed expansive cement concrete as filler concrete between the steel lining and the periphery rock. Its action combines with the inner steel lining, the intermediate concrete and periphery rock, as a result of which various kinds of grouting through steel lining, considered troublesome, could be eliminated. The placing of expansive cement concrete is started Feb. 1973 and ended Oct.. The volume of concrete is 12,125m³.
Measured data on actual steel lined penstock verifies that the results are wonderfully welcome and sufficiently achieved the expected.

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