Journal of Structural Engineering

The size and position of intermediate stiffeners in the compression flanges of thin‐walled profiled steel decks exert a strong influence on the dominant buckling mode of the flange. The ability of the deck to provide both high load‐carrying capacity before the onset of elastic buckling and a high ultimate‐load capacity may therefore be affected. A program of tests to determine the effectiveness of intermediate stiffeners in controlling buckling modes is undertaken. A series of specimens are loaded in pure bending resulting in various buckling waveforms prior to ultimate failure through a plastic collapse mechanism. The experimentally determined buckling stresses are found to be comparable with studies performed using a finite‐strip numerical analysis in which both local, and distortional buckling modes are predicted. A simplified design procedure for distortional buckling is proposed. The existing design procedure for local buckling in the Australian Standard AS1538‐1988 is confirmed.

Formulas to predict the ultimate shear strength of reinforced concrete deep beams are proposed. The derived equations are based on limit analysis theorems and associated flow rule. The lowest upper‐bound solution is achieved through the work equation. With the effective strength concept, the materials are assumed to be perfectly rigid‐plastic. A special constant is introduced to consider the structural effect on the effectiveness strength factor of concrete. For deep beams, this constant is equal to $1.25-0.25\lambda$ where λ is the shear‐span ratio of a deep beam. The interaction between horizontal and vertical web reinforcements is carefully analyzed. It is found that the yield condition of horizontal and vertical web reinforcements depends on the ratio of ${\psi }_h$ and ${\psi }_h$, or the degree of horizontal and vertical web reinforcements. Comparisons with experimental work are performed, and they show good agreement between the proposed equations and test results.

Thermal effects have been frequently associated with concrete‐bridge damage. The nonlinear temperature distributions that arise in bridges are not easily estimated and are often considered in a simplified way, which may lead to structural behavior problems. In the present paper, a discussion of current design‐code provisions is referred to and an approach studied in Southwest Europe is presented. The estimation of the temperature distributions considers a numerical technique for the resolution of the Fourier heat‐transfer equation and its associated boundary conditions. This technique is based on the finite‐element method and takes into account the geometry of the bridge cross section, the thermal properties of concrete and asphalt, the location of the bridge, and the climatic conditions. The results of a parametric study developed to evaluate design thermal vertical differences for typical concrete bridge sections are presented. The numerical technique is also applied to the analysis of special cases in which an accurate estimation of thermal effects is necessary.

Distribution of wheel loads in concrete bridges has been addressed by AASHTO using the effective‐width concept, whereby the load is assumed to be laterally distributed over a width $E$ function of the span and limited to 2.1 m (7 ft). A military handbook addressing flat‐slab pier‐deck design to distribute truck‐crane outrigger loads recommends following these guidelines, although it recognizes that resulting designs are overly conservative. An initial finite element‐parameter study is carried out in an attempt to determine more appropriate effective‐widths values. Inservice pier tests are conducted to corroborate the numerical predictions. From these analyses and test results, a one‐third scale laboratory model using an effective‐width value of 3 m (10 ft) is designed, constructed, and tested. Classical plate‐theory solutions and finite element analyses using various edge conditions, cracked and uncracked deck properties, as well as point and patch loads are completed. Analyses and tests results confirmed that effective‐width values for reinforced concrete slabs can often be doubled over current AASHTO allowables. For Navy pier‐deck designs where large, truck‐mounted cranes dominate load requirements, this will result in higher load capacity, longer spans, and less construction materials.

The paper presents compression tests on square and circular stainless steel tubes, including stub column and long column tests. An important part of the test program was to quantify the increase in column strength resulting from cold work during the fabrication process. Tension and compression tests on coupons cut from finished tubes were also included in the test program, as were measurements of residual strains produced by the cold‐rolling process. A design method is proposed for stainless steel tubular columns. The method incorporates the increase in strength produced by the cold‐rolling process and is validated by comparing it to the test strengths. It is demonstrated that the proposed design procedure provides column strengths that are much closer to the test strengths than design strengths based on the annealed material properties. The design procedure proposed is an extension of that described in the ASCE Specification for the Design of Cold‐formed Stainless Steel Structural Members.

The paper presents tests on square and circular stainless steel tubular beams. An important part of the test program was to quantify the increase in bending strength resulting from cold‐work during the fabrication process. Tension and compression tests on coupons cut from finished tubes were also included in the test program. Stress‐strain curves for shear were obtained using the coupon test results and the concept of affinity factors. A design method is proposed for stainless steel tubular beams. The method incorporates the increase in strength produced by the cold‐rolling process and is validated by comparing it to the test strengths. Design rules are proposed for the bending and shear strengths and for combined bending and shear. The design procedure proposed is an extension of that described in the ASCE Specification for the Design of Stainless Steel Structural Members. The paper describes a simple noniterative method for calculating deflections of stainless steel tubular beams. The method is suitable for design and is shown to produce deflections that agree closely with tests.

The impact behavior of multiple vehicles moving across rough bridge decks on seven multigirder concrete bridges with different span lengths is studied. The bridges are modeled as grillage beam systems. The vehicle is simulated as a nonlinear vehicle model with 12 degrees of freedom according to the HS20‐44 truck design loading in American Association of State Highway and Transportation Officials (AASHTO) specifications. Four classes of road‐surface roughness generated from the power‐spectral‐density function for the approach roadways and bridge decks are used in the analysis. The parametric analysis shows that the impact of exterior girders of short‐span bridges is highly sensitive to such factors as lateral loading position, vehicle weight, road roughness, number of loading lanes, and lateral stiffness. The maximum impact factors of girders were obtained for three trucks (side by side) through changing their transverse positions, with different speeds and road‐surface roughnesses. The results are useful for bridge design and further study of the impact formula proposed by the AASHTO specifications.

The effects of cable‐tension control on guideway deflection of a planar, cable‐stayed support structure for moving vehicles is examined. The structure studied is referred to as double stayed, as it incorporates stay cables both above and below the guideway in a symmetric arrangement. Use of double stay cables allows static guideway alignment to be determined and maintained by cable pretension. A typical guideway section is modeled as a simply supported beam with discrete elastic supports at the cable connections. The supporting pylon is treated as a cantilever beam with concentrated end loads. Fourier analysis and the method of assumed modes are used to solve the coupled equations of motion when the guideway is subjected to a moving constant load. Numerical results show that guideway deflection can be effectively reduced through tension control in the lower stay cables. Modification of lower‐cable tensions in response to external loading has the effect of increasing the load‐carrying ability of the pretension in upper cables.

The behavior of single plate shear connections in steel structures is studied in this paper. Based on the analyses of the test data, new design procedures are developed and presented. The research and the design procedures presented here have formed the basis of the current AISC design procedures in the AISC manuals. Research indicated that the connections designed according to the proposed method possess sufficient shear strength, rotational flexibility, and ductility and can be categorized as simple (pin) connections. In the study, six failure modes were established, and design equations were formulated and proposed for each limit state of failure.

This paper presents the numerical implementation of an analytic procedure for calculating the expected low‐cycle fatigue damage for a structure subjected to a nonstationary load. This implementation investigates a spherical storage tank subjected to earthquake ground motions. Numerical modeling parameters are selected to provide acceptable accuracy and efficient calculation time. The modeling parameters are normalized to permit their application to future studies.

Physical modeling parameters, such as ground‐motion intensity and duration, as well as material properties, such as cyclic strength and fatigue ductility, have a significant impact on the expected damage. Notch effects also affect the expected damage. For parameters representing a moderate earthquake and typical industrial structures and materials, the expected damage in the shell is found to be small. The accuracy of the analytic procedure was verified through Monte Carlo simulation.

In this two‐part paper, responses of two, adjacent, seven‐story buildings in Norwalk, California, to the Whittier‐Narrows, Calif. earthquake of Oct. 1, 1987 are studied. Building A, instrumented according to code recommendations, and building B, extensively instrumented, are offset by 16.3 m from one another. The data set includes motions from the superstructure of both buildings, from a downhole below the foundation of building B, and from three free‐field sites. Part I of the paper includes descriptions of the buildings, site, instrumentation, and analysis of the data of each building. System identification and spectral analysis techniques are employed in part I. Building A has identical first‐mode frequencies of 0.65 Hz for both building axes. The strong‐motion response characteristics of building A are considerably different than those determined from low‐amplitude tests. Building B has fundamental modes at 0.76 Hz and 0.83 Hz in the major and minor axes, respectively. Torsional and diaphragm effects in building B are negligible.

Presented in this part of the two‐part paper is a study of the relations between earthquake motions recorded from two, adjacent, seven‐story buildings, from a downhole below the foundation of one of the buildings and from three free‐field sites, all within one city block. This unique data set was obtained during the Whittier‐Narrows, Calif. earthquake of Oct. 1, 1987. Part I includes background information on the two buildings, the site, and the data set. Building response characteristics of a code‐type instrumented building (A) and an extensively instrumented building (B) are also studied. In this part, spectral analysis techniques are used to study the relationships between the motions of the roofs and basements, the downhole and the free‐field sites. It is asserted that there is building‐soil‐building interaction between the two buildings at a frequency of 2.35 Hz. Furthermore, the free‐field motions are shown to be influenced by the presence of the buildings.