Journal of Structural Engineering

Tests were performed to determine shear load‐displacement relationships for three different anchors used to attach a steel liner to the concrete in a reinforced concrete primary containment: (1) The metric tee $100\mathrm{mm}\times 100\mathrm{mm}$ with 1/4‐in. (6.4‐mm) fillet welds which was used to anchor the containment liner at the Public Service Company of New Hampshire's Seabrook Station; (2) the WT $4\times 7.5$ with 3/16‐in. (5‐mm) fillet welds used at the Washington Public Power Supply System's Nuclear Power Station; and (3) 3/4‐in. (19‐mm) diameter × 12‐in. (305‐mm) long studs, also used at Seabrook. A 3/8‐in. (10‐mm) thick liner plate was used. The test specimens consisted of tees which were 12 in. (305 mm) long or two studs spaced 12 in. (305 mm) apart embedded in a concrete block $40\mathrm{in}\text{.}\times 36\mathrm{in}\text{.}27\mathrm{in}\text{.}$ $(1\text{,}016\times 914\times 686\mathrm{mm})\text{.}$ The specimens were fabricated and cast at Seabrook. The tests were controlled by dialing in a voltage at the test console which corresponded to a known deflection; the load necessary to produce this deflection was then recorded. Loaddeflection curves for all tests are presented as a conservative representation of the shear load‐deflection behavior of a loaded anchor.

Reinforced concrete beams were tested to failure in torsion. The same beams were repaired by adhesively bonding steel plates to one side of the beam. The repaired beams showed a 33% increase in strength over the original beams, when subjected to identical loading. The repaired beams all failed in flexure, rather than torsion and showed a deflection 25% less than the original beams. Control beams, externally reinforced before loading, showed a 43% strength increase and also failed in flexure.

Earth sheltered housing is a viable means of achieving superior energy performance, lower maintenance cost, and protection from extreme weather. Despite demonstrated potential for large‐scale acceptance in the housing market, initial costs are currently too high to realize this market potential. At least part of the cost problem in earth sheltered construction is attributable to the common practice of using conventional, rectilinear structural systems intended primarily for lightly loaded aboveground buildings. Thin concrete dome shells are logical alternative structural forms to efficiently support relatively massive soil loads. This paper evaluates the strength and stability of 50‐ft (15‐m) diameter, 4 in. (102 mm) nominally thick concrete spherical domes under 3 ft (0.9 m) of saturated soil cover. Domes having diameter‐to‐rise ratios between two (hemispherical) and twenty are analyzed for stress levels and buckling characteristics. Neither stress levels nor stability considerations severely limit the range of feasible dome profiles, making the thin concrete dome shell an effective structural system for earth sheltered residential applications. From the perspectives of both structural and architectural design, thin concrete dome shells offer significant potential for application in earth sheltered housing.

Charts are presented for the seismic design by the response spectrum method of fixed‐base multistory buildings consisting of solid shear walls and frames, symmetrically arranged in plan and having constant properties along the height. The building is treated as a continuum with the frames modeled as a single shear beam, and the first three normal modes of the building are utilized for evaluating various modal responses, namely, the bending moments and the shear forces in the wall, the shear force in the frame and also the top deflection, the contribution of only the fundamental mode being considered for the last named response. The charts present the distributions of the modal moments and shears along the height of the building, which should allow the quantity of reinforcements to be varied for achieving economy. The results are presented for practical values of the nondimensional parameter which incorporates all the geometric and material properties governing the behavior of the system. The use of the design charts is illustrated by an example of a 15 story building.

A beam under load can be more easily twisted or deflected laterally than when not under load. This loss of apparent stiffness is an example of the general principle that stiffness associated with a buckling displacement diminishes to zero as the buckling load is approached. This phenomenon was first reviewed and derived for beam‐columns and then derived for beam‐torsion members. It was found that stiffness decays linearly for beam‐columns and parabolically for beam‐torsion members. The results are important to designers of large flat roofs in which one beam must provide axial rotation restraint for the next beam in‐line. Simple design equations are recommended.

This paper describes and illustrates a methodology with which alternative design strategies for offshore platforms in combined loading environments may be assessed. The methodology is structured around a decision analysis approach to evaluating and selecting among alternatives. Experience with application of this approach to engineering structures for new offshore frontiers, such as the arctic and deep water, indicates that it represents a powerful tool to assist development of optimum engineering decisions.

The work presented in this paper shows that hyperboloid shells can be inexpensively analyzed under the action of concentrated loads using an axisymmetric program. From the point of view of behavior, the numerical analyses pointed out that a negative curvature shell under the action of a concentrated load tangent to the meridian develops important bending moments and out of plane shears as a condition for the distribution of the concentrated load throughout the shell. It also exhibits a tendency of the stresses to propagate along the straight line generatrices as in the membrane theory; but the numerical results of the membrane theory can be misleading. Under a self‐equilibrating harmonic load tangent to the meridian this shell shows a rapid damping of the stresses away from the edge when the harmonic number is high (usually as $n⩾5$). The increase in the ratio h/R and the decrease in the foundation stiffness are two factors that reduce the membrane propagation and increase the bending moments.

The effect of varying amounts of transverse and longitudinal reinforcement on behavior of short reinforced concrete columns was studied. The short columns were cyclically deflected along their diagonals to produce bilateral deformations more representative of severe earthquake loadings. Bond degradation was found to be a serious problem in some columns. The rates of degradation of the hysteretic load‐deflection loops were strongly influenced by the spacing of the transverse reinforcement. The importance of transverse reinforcement to shear resistance in the form of inclined crack width control was confirmed. The ACI 318‐77 shear capacity equations were found to be conservative. Trends indicated by the equations were not observed in the column tests.

A finite element analysis has been made of the stress distribution in a slab coupling a pair of laterally loaded flanged shear walls. For a unit relative wall rotation, or relative vertical displacement, distributions of critical bending moments have been determined, and a generalized design curve presented to allow rapid evaluations of the maximum moments in a slab coupling a pair of T‐shaped walls. An investigation of the distributions of interactive shear forces between wall and slab, in conjunction with the usual design assumptions regarding shear failure of similar flat plate structures, has enabled a design technique to be proposed for checking against punching shear failure of the slab. Design curves are also presented for the critical bending moments in slabs coupling plane and T‐shaped walls, and L‐shaped walls.

In contrast with the work reported on the shear behavior of reinforced concrete elements subjected to unidirectional loading, the behavior of reinforced concrete members subjected to multiaxial loadings has received little attention. This paper describes an experimental study of the behavior of short columns subjected to different cyclic lateral loading (deformation) histories. The influence of loading history on the deterioration of shear strength and stiffness was examined. A total of 18 specimens was tested—10 without axial load and 8 with various axial load histories. The geometry of the specimens was not changed. The results indicate the effect of sequence and magnitude of lateral deformation and axial load on the shear response of short columns.

In the design of elevated vehicle/guideway systems several parameters play important roles in the dynamic performance. The vehicle inertial and suspension properties, guideway mass per unit length, span length, structural damping characteristics and surface finish tolerances are important factors. The two most important dynamic phenomena which require accommodation in the system design are vehicle suspension resonance and guideway beam resonance. For a given system configuration there exists an optimal span length which will yield the best dynamic performance. Furthermore, there exist critical ranges of span lengths, shorter than the optimum span, which will cause resonant guideway and vehicle vertical oscillations unless much stiffer guideway sections are used. A detailed dynamic assessment of the optimum simply supported guideway span length is presented. The effects of all parameters to the system performance are examined and critical parametric combinations are identified for a practical design example of vehicle/guideway system.

Softening behaviour, or decrease in bending moment capacity at far advanced curvature, is assumed to occur over a finite hinge length, or discontinuity length, at any point in a single-bay portal frame. The critical softening parameter, a_cr, is defined as that ratio of falling-arm slope to elastic slope on the moment-curvature diagram for the hinge, at which the structure as a whole cannot sustain increased load, however redundant it may still be. Formulae are derived for a_cr for the first formed hinge in fixed base portal frames. The critical softening parameter is found to be inversely proportional to the member-length : hinge-length ratio, m. For realistic values of m, appropriate formulae for a_cr are found to be quite accurate. For given frame geometry ``soft points'' at which a_cr is a minimum may be found for each member.

Tests of clip angle connections are described in which a constant beam shear exists while reversed cyclic loading along the axis of the beam is applied. The connections retain their ductility and exhibit considerable reserve of strength after fifteen cycles of load at high load amplitudes. An estimate of the reserve strength, based on the tests, is given.