Beam Section Size Research Articles

Scaling laws of low-velocity impact response for RC beams: Impact force and reaction force

Predicting the low-velocity impact response of the prototype based on the scaled test results is one of the significant topics in structural design and protection. Thus, reliable similarity laws are required to bridge the dynamic similarity between models and prototypes. In this study, numerical modeling was carried out by considering plastic damage and strain rate effects. Then, the impact responses of four series reinforced concrete beams satisfying traditional similarity laws were analyzed. The largest beam section size reached 600 mm × 1000 mm. The scaling effects on the impact force profiles (comprising three Types) and reaction force profiles of the beam were investigated. Several characteristic points were defined for the available simplified profiles of impact and reaction forces. It is shown that the scaling effects on each characteristic are not consistent. As the theoretical scale factor increases, the characteristics such as the peak impact force, the positive peak of the reaction force, and its plateau satisfy the traditional similarity law, whereas the characteristics such as the impact force duration and the negative peak of the reaction force do not. Therefore, modified dynamic scale factors for the characteristics of impact and reaction force profiles from models to prototypes were proposed. Based on the suggested scaling laws, the simplified profiles of impact and support reaction forces of the prototype can be predicted. It is expected that it will help researchers to conduct experimental studies and optimized designs on structural impact resistance.

Experimental study and numerical simulation on shear behavior of steel and concrete composite beam with molybdenum tailing

To improve the flexural performance of steel–concrete composite beams and alleviate the problem of sand depletion caused by the application of concrete structures, this paper proposes a new type of steel-molybdenum tailings concrete composite beam. In order to further study the shear performance of the new type of steel-molybdenum tailings concrete composite beam, this paper couples molybdenum tailings replacement ratio (0%, 50%, and 100%) and shear span ratio (1 and 2) as research parameters, designs a total of six 1:2 scaled composite beam models, and conducts monotonic loading tests to study the failure process, failure mode, ultimate bearing capacity, deformation, and local strain of some typical measuring points of the new composite beam. The steel and concrete composite beam with the molybdenum tailing has the similar mechanical behavior for each ratio of the shear span to the effective depth with that of the steel and concrete composite beam. In addition, they have a little difference in the failure processes for each ratio of the shear span to the effective depth, whereas they show typical diagonal compression failure mode for the ratio of the shear span to the effective depth is equal to 1 and the representative shear-compression failure mode for the ratio of shear span to effective depth is 2, and have no obvious difference in failure mode for each ratio of the shear span to the effective depth. Their shear resistance mechanism is basically the same. Furthermore, based on the validated finite element model, this paper conducted a parameter extension analysis. The finite element results show that: The ultimate load bearing capacity of the steel and concrete composite beam with molybdenum tailing varies significantly with the beam section size (beam section width and beam depth), reinforcement ratio, and the ratio of the shear span to the effective depth; Whereas it has little relation to the steel plate thickness. This provides the necessity and feasibility to use the steel and concrete composite beam with the molybdenum tailing in engineering practice. The proposed equation in this study is based on the previous researches and the simulated and test results. The proposed equation is rigorous and thorough and the predicted results are highly accurate and effective.

Multilinear model for progressive collapse response of reinforced concrete frames under penultimate column removal scenario

When local damage occurs due to unexpected events, compressive arch action (CAA) and catenary action (CTA) increase the progressive collapse resistance beyond the conventional plastic hinge mechanism. To investigate the progressive collapse behavior, large-scale structural tests and/or finite element analysis are performed, which are time-consuming and requires in-depth professional knowledge. In the present study, a multilinear model was developed to evaluate the progressive collapse resistance of moment sub-frames after the removal of a penultimate column. To estimate the load-carrying capacity and corresponding deformation at each mechanism, the effects of boundary condition, and the geometric and material properties of the beam section on the structural performance were considered. The validity of the proposed method was verified by comparison with the existing test results of moment sub-frames under progressive collapse. Further, a parametric study was performed to investigate the effects of concrete strength, reinforcement ratio, beam section size, and beam span on the progressive collapse resistance of the substructure. The analysis results showed that increasing the beam depth or beam top rebar ratio significantly increased the progressive collapse resistance.

A method to solve discrepancies of scale model in seismic shake table test of quayside container crane

ABSTRACT The quayside container crane (QCC) scale models for seismic simulation test on vibration tables are often high, and the model size and QCC structural size differences introduce discrepancies into the QCC model. In this investigation, discrepancies in the QCC scale model were solved using the similarity method for the sectional radius of inertia. Firstly, a governing equation for the beam section size was established. Secondly, a scale model was constructed for the shake table test, and the results were compared with the simulations. It is demonstrated that the experimental results were close to the simulations. Specifically, the acceleration, strain extreme values, and the time of occurrence were similar at different QCC points. This reveals that the shake table test of the QCC scale model can approximately reflect the prototype seismic response, which verifies the feasibility of the model design method.

FLEXURAL PERFORMANCE OF COLD-FORMED THIN-WALLED STEEL-PAPER STRAW BOARD COMPOSITE SLAB

A new type of composite slab was proposed by connecting paper straw board and cold-formed thin-walled steel with self-tapping screws. In order to investigate the failure process and failure mode of the composite slab, the tests on the flexural capacity of three composite slabs with different factors such as steel beam section size, beam spacing and the number of screws were carried out. The strain of the cold-formed thin-walled C-shaped steel and the paper straw board, and the deflection of the composite slab were observed, respectively. Moreover, the flexural behaviour and the composite action of the composite slab were investigated and the flexural capacity of the composite slab was obtained. It was found that the final failure mode of composite slab was the local buckling mode of cold-formed thin-walled C-shaped steel beam due to the adequate restraint of the straw board, and the reducing of the screw spacing had beneficial influence on the flexural yield capacity. The calculation method of midspan deflection and flexural capacity of composite slab were proposed, and the calculated values of deflection and flexural capacity agreed well with the test results. Therefore, the new composite slabs were of good working performance and high flexural capacity.

Static and dynamic loading tests for precast concrete moment frames under progressive collapse

Precast Concrete (PC) building structures are weak to progressive collapse due to discontinuity of reinforcement at beam-column joints. In the present study, four static loading tests and two dynamic loading tests were performed to investigate the progressive collapse resistance of conventional PC moment frames. The test parameters were the connection detail, bar development length, beam section size, and rebar ratio. The structural performance, such as the load-carrying capacity, deformation capacity, failure mode, and rebar strain, were evaluated. The test results showed that the progressive collapse resistance was significantly affected by the connection detail and beam rebar ratio. Based on the static loading test results, dynamic loading with multi-stage load conditions was applied to two PC specimens. The progressive collapse resistance of the specimens under static and dynamic loadings was compared, and the effect of dynamic loading was discussed.

Cyclic Behavior of Anchored Blind-Bolted Extended End-Plate Joints to CFST Columns

As the square steel tube in the tension zone is always the weakest part of moment-resisting joints, modified blind bolts (Hollo-Bolts) and a locally strengthened steel tube in the panel zone were adopted to enhance the joint performance. Cyclic loading tests were carried out on eight anchored blind-bolted extended end-plate joints between square concrete-filled steel tube (CFST) columns and steel beams. The test parameters included the end-plate thickness, steel tube wall thickness, beam section size, local strengthening connection method, blind bolt anchorage method, and stiffeners. The failure mode, hysteretic behavior, stiffness, strength, ductility, strength degradation, stiffness degradation, and energy dissipation capacity of the joints were studied and analyzed. The test results showed that the application of anchored blind bolts and a locally strengthened steel tube can fully utilize the bolt strength and significantly improve the joint performance, especially in terms of strength and strength degradation. The test observations revealed three typical failure modes for the joints, and the failure mode depended on the weakest component. In addition, the local reinforcement of C-channel and change in the anchorage method had a limited effect on the initial stiffness. Greater end-plate thickness and the use of stiffeners significantly increased the joint stiffness and decreased the rate of stiffness degradation. The use of stiffeners also significantly enhanced the ductility and energy dissipation by moving plastic hinge outward from the joints. Finally, finite element analysis (FEA) models were developed and validated against the experimental results, and the stress distribution and force transfer pattern were investigated.

Collapse analysis of regular and irregular tall steel moment frames under fire loading

SummaryThis study is carried out to evaluate the progressive collapse of steel buildings under fire event. To this end, a 15‐story steel structure with moment‐resisting system and composite floors is considered. The effects of various parameters such as beam section size, gravity load ratio, vertical irregularity of resisting system, and location of fire compartments on collapse modes are investigated numerically. Different temperature‐time curves are defined across the composite floors according to the Eurocode 4. It is found that local collapse of the frames at the ground floor fire is triggered by the buckling of the interior heated columns at approximately 540°C. The redistributed loads by floors delay the global collapse at least 45 min. Increasing gravity loads accelerates the global collapse of the frames significantly. The heated columns of the middle floor buckle at higher temperature compared to the ground floor heated columns and no global collapse occur due to this scenario. In general, the potential of collapse of the regular and irregular frame due to fire in the edge bay is higher compared to the fire in the middle bay. It is also found that the local and global collapse of regular frames occur earlier than irregular frames.

Computational analysis of thermal and structural failure criteria of a multi-storey steel frame exposed to fire

Structural fire design, until recently, has only assumed uniform fires inside the compartment, and the assessment of structural failure has been often based on a critical temperature criterion. While this criterion, to some extent, may be able to indicate the temperature at which the structural element is near to failure, it is based on standard fire tests and, therefore, its validity is limited to individual members exposed to uniform temperatures. It is unclear how representative a critical temperature criterion is of structural failure in the case of multi-story structures, particularly in the case of non-uniform fires such as travelling fires. Therefore, the aim of this study is to assess the validity of the critical temperature criterion for structures exposed to non-uniform fires and compare it to uniform fires. A generic 10-storey steel framed building is modelled using the finite element software LS-DYNA. In total, 117 different scenarios are investigated to cover a wide range of conditions of interest for design of modern steel buildings, varying the fire exposure (travelling fires, Eurocode parametric fires, ISO-834 standard fire, and SFPE standard), floor where the fire is burning, beam section size, and applied fire protection to the beams. For the different fire exposures considered, the analysis predicts structural failure at different times, in different locations and floors, and different failure mechanisms. Moreover, it is shown that there is no single worst case fire scenario: different fires can lead to failure in different structural ways. The comparison of the various structural and thermal failure criteria (ultimate strain, utilization, mid-span deflection, and critical temperature) show that there is no consistency between them, revealing a far more complex problem than reported in the literature. Lastly, this work has illustrated that the critical temperature criterion does not predict accurately the structural failure in time, space or failure mode of steel structures subjected to both uniform and non-uniform fires. Structural failure can only be predicted by advanced structural analysis, and, therefore, heat transfer analysis alone is not sufficient for design. Nevertheless, it was shown that the use of the critical temperature leads to conservative results for simple steel structures. For the sake of comprehensive design, a range of different fire scenarios, including both uniform and non-uniform, should be part of the analysis such that all likely structural responses and failure modes can be considered.

Stability of reticulated shell with steel panel as the bracing and time-varying structure for LNG tank during concrete dome casting

With the growing demand of energy for recent decades, liquefied natural gas (LNG) has become one of the most significant energy sources due to the high calorific value and performances, as well as the ease of transportation and storage. Hence, many LNG tanks have been constructed to store liquefied nature gas and the roof of a LNG tank consists of reticulated shell, roof panel and concrete dome. The ribbed-type reticulated shell welded to the roof panel, which is called roof panel enhanced (RPE) reticulated shell in this paper, can be treated as the template during concrete dome casting. In addition, it also sustains the gravity load of concrete dome before concrete hardening and works together with concrete dome as a composite structure after concrete hardening. It is of significance to study the response of RPE reticulated shell during the construction stage. In the first part of this paper, the nonlinear load–deflection complete process analysis was carried out to study the buckling behavior of the RPE reticulated shell under uniformly distributed load. The effects of beam section size, rise-to-span ratio and the initial geometric imperfection magnitude on the buckling resistance of the RPE reticulated shell were investigated to optimize the current design. In the second part of this paper, the buckling behavior of the RPE reticulated shell under non-uniformly distributed load induced by concrete dome casting was studied and the air pressures of each construction step were determined by considering the response behaviors of the time-varying structures composed of RPE reticulated shell, concrete dome and changing load. The safety factors of the RPE reticulated shell were calculated under the appropriate air pressure and initial geometric imperfections, based on which, the original optimized design of the RPE reticulated shell was improved to reduce the material consumption.

Seismic performance of a new through rib stiffener beam connection to concrete-filled steel tubular columns: An experimental study

This paper proposes a new moment-resisting connection known as a through rib stiffener beam connection, which is directly passed through a pre-slotted circular column with concrete infill. Four half-scale cruciform specimens with orthogonal beams were tested under cyclic loading. The failure modes, hysteretic performance, rotation capacity, strength and stiffness degradation, ductility, and energy dissipation of the connections were analysed. The effect of different parameters, such as through rib stiffener and beam section size, on the connection performance was investigated. The experimental results indicated that the new through rib stiffener beam connected with circular columns exhibited a large hysteretic enclosed area, good ductility, and excellent energy dissipation. The results proved that the proposed connection satisfies the seismic provisions and ductility design requirements for it to be utilized as moment-resisting frames in a seismically active area.

Pengaruh Penambahan Tulangan Bambu terhadap Kuat Lentur Panel Semen Eceng Gondok

This study is a follow-utilization of water hyacinth as a building material wall panel (Emen wall). From previous studies, physical properties, mechanical, acoustic and endurance burn this material meets the standards of building materials PUBI 1982 and ISO and ASTM C423-90a 03-6861.1-2002. In this study, the variable still is a variation of the test specimen without reinforcement with reinforcement of bamboo and bamboo in the form of a model variation of the beam section size (15x20cm) and sectional plates (5x15cm). While the independent variable is in the form of bending strength and deflection in the test specimen. The results showed the effect of bamboo reinforcement against bending strength cement panel hyacinth. On the test object model of the beam section with bamboo reinforcement ratio r = 0, r= 0.006 and r = 0.01 , powerful bending P = 24kg, P = 59kg and P = 72kg. To model the cross section of the plate with a bamboo reinforcement ratio r = 0, r = 0.017 and r = 0.025 , stronger bending is P = 3,33kg, P = 16,33kg and P = 21,83kg.

梁断面寸法と接合詳細が変形能力に及ぼす影響

This paper presents results of full-scale cyclic loading tests of moment connection under constant deformation amplitude conducted to evaluate deformation capacity. The effects of beam section size and of weld access hole are investigated by four type specimens. The relationships between ductility amplitude of beam rotation, cumulative plastic deformation and crack propagation at weld joint are quantitatively obtained from test result. The effects of beam section size and connection detail on crack initiation charactaristic are investigated from stress and strain by FEM analysis.

Research on Load Distribution Effect of Load Distributed Structure in the Complex Rotational and Translational Engineering

In view of the large axial force column underpinning of the complex rotational transportation engineering，a new underpinning structure which with six diagonal bracings was proposed in this paper. Using SAP2000 software built four different calculating models with different support forms, and analyzed internal forces of members of the underpinning structure, discussed the load distribution effects on change of parameters including the inclined angle α between the inclined support and column, the angle θ between the inclined support horizontal projection and axis, inclined support section sizes, coupling beam section size and whether there are the horizontal forces. The results show that the load distribution effects of whole model and of single column model have little difference, but the single column model underestimates the axial forces of the inclined supports. α and θ have a great influence on load distribution effect, and smaller α is better. The load distributed result can be very good to meet the requirement of rotating shift engineering.

Experimental Research on the Cracking Behavior of GFRP/Steel Wire Composite Rebar Reinforced Concrete Beam Based on Cracking Mechanics

The different mechanical property determines the difference on cracking behavior between GFRP/steel wire composite rebar reinforced concrete beams and steel rebar reinforced concrete beams according to cracking mechanics. In order to study the cracking behavior of concrete beams reinforced with GFRP/ steel wire composite rebar, five simply-supported beams were tested under three-point static load. The test variables were beam section size and concrete cover depth. Based on analysis on the test results, the calculation methods of cracking capacity and maximum crack width were proposed, and the limit value of crack width was suggested.

Nonlinear Analysis of FRP SRC Concrete Beams

On the basis of the theory of FRP sheet steel reinforcing concrete beams (SRC-beams), in order to better explore the force performance of FRP (Fiber Reinforce Plastic) steel reinforcing concrete beams, this paper analyzes the stress process simulation of the beam using the computer program of nonlinear analysis. In order to validate the program of the beam section the reliability of the simulation analysis, this paper brings beam section size and its material performance parameters into program and gets different parameters on the bearing capacity of beams influence law. Research shows that when working in the stage of FRP elasticity the reinforcement of FRP layers has little influence on bend curvature figure. In the elastic-plastic stage it has larger influence and the cure increases with the increase of FRP reinforcement layer. It shows that with the increase of the section stiffness beam bending flexural capacity is also bigger.

The Design Method Study of Double Reinforcement Beam Section

To simplify the reinforcement design process of double reinforcement beam section, the concept and application of double reinforcement bean section were introduced, and the appropriate application conditions of reinforced beam in practical engineering and the structural design requirements of beams with double reinforcement section designing were analyzed. The results show that the design value of the negative moment, the beam section size and strength grade of concrete shall meet his requirements of the structural design, then the relational expression is derived, applying this formula to judge whether they meet the preliminary requirements before the calculation of beam reinforcement. Compared with the engineering example shows that the design equations is more simple and accurate, but is the upper limit, and the results can provide a reference for the engineering design and related research.