Journal of Structural Engineering

An ultimate strength analysis procedure was formulated for five full‐scale, two‐way slabs tested to failure. The concrete slabs were reinforced with composite corrugated cold‐formed steel decking. Three slabs contained supplementary reinforcing in the form of welded wire fabric. Nominal out‐toout plan dimensions of the slabs were 16 ft by 12 ft (4.88 m by 3.66 m). All slabs were subjected to four symmetrically placed, concentrated loads. Utlimate failure occurred by a shear‐bond action initiated by slippage between the steel deck and the concrete. The analysis procedure was founded on the principles of yield‐line theory and of shear‐bond regression analysis. A collapse mechanism established by yield‐line procedures was utilized to determine the effective load‐carrying‐segment width of the slabs. A shear‐bond regression analysis was used on the effective width to predict the total shear force distributed to the reactive edge perpendicular to the deck corrugations. The shear existing along the sides of the effective load‐carrying segment was subsequently added to the shear‐bond component to give the predicted ultimate load for each slab. The calculated load agreed very closely (within 9%) with the experimental ultimate for all five slabs.

Stiffness and consistent mass matrices for linearly tapered beam element of any cross‐sectional shape are derived in explicit form. Exact expressions for the required displacement functions are used in the derivation of the matrices. Variation of area and moment of inertia of the cross section along the axis of the element is exactly represented by simple functions involving shape factors. Numerical results of vibration of some tapered beams are obtained using the derived matrices and compared with the analytical solutions and the solutions based upon stepped representation of the beams using uniform beam elements. The significance of the severity of taper within beams upon solution accuracy and convergence characteristics is examined.

A procedure is presented for estimating the wind‐induced response of tension leg platforms (TLP). Spatiotemporal characteristics of the wind velocity field over the ocean are discussed. It is shown that the wind spectra generally used for land‐based structures may not adequately represent wind velocity fluctuations at very low frequencies associated with the compliant modes of a TLP. A new spectral description of the longitudinal wind velocity fluctuations over the ocean is proposed. The wind approaching a TLP is treated as a single‐point and a multiple‐point random field. Expressions for the wind loads in the surge, yaw, and pitch degrees of freedom are formulated in both time and frequency domains for subsequent dynamic analysis. To account for the nonlinear behavior in the frequency domain, the mean response of a TLP is computed using nonlinear stiffness characteristics of the system. For unsteady response due to the wind fluctuations, the TLP is assumed to oscillate linearly above the static equilibrium position produced by the mean wind loading. A numerical example illustrates the methodology outlined for predicting the response statistics of a typical TLP. It is verified that the TLP response estimates based on frequency and time domain analyses show good agreement for the platforms investigated. The frequency domain analysis is recommended for estimating the wind‐induced response at the preliminary design stages, to be followed by the time domain analysis in the final stages.

This paper briefly summarizes some of the results of tests on three full‐size stub‐girders. The objectives of the investigation were to study the failure mechanism and to evaluate the effectiveness of three different types of transverse slab reinforcement in increasing the longitudinal shear capacity. Deflection characteristics and general structural behavior were also studied. In all cases, failure involved crushing of the slab over the interior end of the end stub accompanied by a shear/splitting failure in the slab over the length of the end stub. The observed ultimate load on the stub‐girders exceeded the design ultimate load by 45%, 14% and 21% respectively for Specimens K‐1, K‐2 and K‐3. Straight transverse reinforcing bars in addition to temperature and shrinkage reinforcement, had little effect on the stub‐girder capacity. The incorporation of a wide concrete flute along the slab centerline, together with bent transverse bars significantly increased the ultimate capacity and improved the ductility of the stub‐girder. The specimens tested were very stiff and would meet normal deflection requirements under service loads.

In order to utilize a limited length of wind records in providing extreme wind speeds for structural design, a stochastic model for generating long‐term annual extreme winds in a well‐behaved climate, on the basis of short period records, is developed and presented herein. Basically, this method uses historical wind data to establish Markov transition probabilities at an intended project site. These probabilities will be the guide for producing synthesized hourly wind speeds of a desired period, i.e., 100 annual extreme wind speeds would be obtained if hourly wind data for 100 yr were generated. Furthermore, if correlation is observed between the historical annual extreme winds and annual fastest mile wind speeds at a given site, then long‐term annual fastest mile wind speeds can be obtained. Applications of this model are demonstrated. The simulated 25‐yr, 50‐yr and 100‐yr wind speeds compared very favorably with those obtained by fitting Type I distribution of the largest values to the 33 historical annual fastest mile wind speeds for the Honolulu International Airport. However, the results from the proposed simulation model are less favorable for generating extreme winds for typhoon‐prone regions on the basis of short period historical data.

An experimental investigation on inelastic buckling of plates simulating simply supported webs and flanges was conducted. The test results are compared with values predicted using the results of standard tensile coupon tests and inelastic orthotropic material properties suggested by various investigators. A set of orthotropic material properties, derived semi‐empirically as a result of this study and in good agreement with test results, is suggested. Agreement between predicted values of buckling loads and test results obtained in this investigation and from other researchers validates the use of these material properties for predicting inelastic plate buckling behavior.

Specifications for masonry and other construction materials are expected to move gradually over the next several years toward the adoption of probability‐based limit states criteria for design. This paper illustrates how such criteria might be developed for brick and concrete masonry construction using, as an example, masonry walls loaded in combinations of axial compression and out‐of‐plane flexure. The paper identifies the type of data and analyses that are necessary to develop probability‐based resistance criteria.

A series of six wood T‐beams, with elastomeric adhesive bonded flange‐to‐web connections, were tested to compare the measured behavior with that anticipated by the design. The parameters measured were deflection at midspan, stresses at the extreme fibers and the flange‐web interfaces, and glue line shear stress. The design method overestimated by an average of 6%, underestimated maximum extreme fiber stress by an average of 10%, and overestimated maximum glue line shear stress by about 12%, for T‐beams with continuous flanges. T‐beams with transverse flange gaps (unconnected butt‐joints) of varying frequency were tested to observe the effect on performance. One gap at midspan reduced the composite action by 77%, two gaps reduced it by 81% and three equally spaced gaps reduced it by 89%. Flange gaps produced extremely high shear stresses in the glue lines in the vicinity of the gaps. The study results for T‐beams with continuous flanges followed the design theory quite well. The flange gap effects were also consistent with theoretical expectations.

Reliability analysis of structural members subjected to a stochastic load process is extended to include material nonlinearity. Characteristics of the nonlinear response are computed for a member with a bilinear force‐deformation relationship having the unloading range parallel to the initial elastic range. The expected number of loads exceeding a predetermined deformation level is derived for a Poisson load process with rectangular pulses. It is found that the derived values agree very well with those obtained from the simulated sustained load processes. The expected damage duration (the total time a process spends above the threshold deformation level) is also derived. For a square wave process, the derivation is theoretically exact once the expected number of exceedances is known.

A direct design method for determining the required column dimensions, concrete strength, and reinforcement arrangement is presented. The user need know only the n triplets $({\mathrm{Pe}}_x{e}_y{)}_1\text{,}$ $({\mathrm{Pe}}_x{e}_y{)}_2\text{,}\cdots ({\mathrm{Pe}}_x{e}_y{)}_n\text{,}$ which the column must resist. A field of acceptable solutions are computed. If the user supplies the in‐place costs of steel, concrete, and formwork, then the program computes a relative cost factor for each design to assist the user in selecting an economical solution.

Approximate formulas for assessing the strengths of plates having various edge support conditions and subjected to uniaxial loading have been presented; the edges may be free to pull in or constrained to remain straight. Plates having the loaded and unloaded edges subjected to 15 combinations of edge supports (selected from simple supports, encastré supports and edges free‐to‐wave) have been studied and comparisons made on the effect of the support conditions upon the first‐yield strengths.

This paper deals with the experimental investigation of dynamic pressure exerted by a granular material (grit) on the walls of a silo. Experimental set‐up with the pressure measuring technique and recorded investigation results are presented. Using dimensional analysis, a formula for the pressure on the walls of a silo is developed in terms of dimensionless parameters, ir(. The self‐induced vibration theory is used to interpret the experimental results. The general scheme of self‐induced vibration systems is examined and a silo with the granular material is identified as one of the self‐induced vibration systems.

A general form of prediction equation is presented for the strength of reinforcing bar development, lapped bar splices, and hooked bar anchorages in reinforced concrete. The form of the prediction equation shows bond strength as a function of the square root of the development length, cover, and transverse steel ratios, as well as the cube root of the concrete strength. Nearly mean value prediction behavior is indicated for all categories of bar development test data. The equation has applications in both research planning and analysis, and in calibration studies for the related understrength factors for strength design. Results of the analysis of bar development data show significant effects of diagonal cracking, multiple bar groups, and moment gradient on development strength.

The grid frame approach for analyzing reinforced concrete beams with large openings has been developed in this paper. In this approach, the beam with large web openings is visualized as a grid frame comprising two longitudinal stringers connected by posts between consecutive openings. For analyzing the grid frame, the twisting couple at each end of the beam is replaced by a statically equivalent system comprising two equal and opposite forces. The ultimate torsional strength computing using the grid frame approach has been compared with the observed ultimate strength of 25 specimens tested by the writers and other investigators.