When the shear resistance of prestressed beams with stirrups is determined with the current Euroc... more When the shear resistance of prestressed beams with stirrups is determined with the current Eurocode, no distinction is made between regions with and without flexural cracks. This while it may be expected that a region without flexural cracks will have a higher shear resistance. This is due to the lower longitudinal strains and the narrow crack widths, resulting in a higher contribution of aggregate interlock. Also, the Eurocode does not take into account that in regions without flexural cracks, a significant part of the shear force is transferred through the uncracked flanges. This article proposes therefore a shear resistance model, based on Modified Compression Field Theory (MCFT), that does consider the low longitudinal strains and shear transfer through the uncracked flanges. From a comparison it was found that the proposed model can determine shear resistance as accurately as the most comprehensive level III approach of the Model Code 2010. However, the proposed model was foun...
The capacity of solid slab bridges in shear is assessed by comparing the design beam shear resist... more The capacity of solid slab bridges in shear is assessed by comparing the design beam shear resistance to the design value of the applied shear force due to the permanent actions and traffic loads. The transverse distribution of loads which occurs in slabs is thus not taken into account. Experiments on slabs under concentrated loads are carried out at Delft University of Technology. The results of these experiments are the basis for recommendations for the assessment of solid slab bridges. A slab factor and a horizontal load spreading method to determine the effective width are proposed. Preliminary results from an additional series of experiments confirm the hypothesis of superposition.
In de afgelopen decennia zijn verkeerslasten en de verkeersintensiteit op de Nederlandse wegen e... more In de afgelopen decennia zijn verkeerslasten en de verkeersintensiteit op de Nederlandse wegen en kunstwerken drastisch toegenomen. Veel van die kunstwerken zijn uitgevoerd als plaatviaducten zonder schuifwapening. De vraag bestaat of het afschuifdraagvermogen van deze viaducten nog steeds voldoende is. Op basis van experimenteel en literatuuronderzoek is een nieuw lastspreidingsmodel ontwikkeld aan de TU Delft voor toepassing in de quick-scanmethode van Rijkswaterstaat.
As a result of the heavier live load models and more conservative shear approaches prescribed by ... more As a result of the heavier live load models and more conservative shear approaches prescribed by the recently implemented Eurocodes, a large number of existing reinforced concrete solid slab bridges in the Netherlands were found to be shear-critical. The beneficial effect of the transverse load redistribution in slabs under concentrated loads is not taken into account. To quantify this effect, a comprehensive number of experiments was carried out. These results are used to formulate recommendations for the assessment practice for the case of solid slab bridges. The recommendations focus on the effective width over which the axle load can be distributed and its lower bound, the beneficial effect of transverse load redistribution and the influence of the yield strength of the reinforcement on the lower bound of the shear capacity. These recommendations are implemented in the “Quick Scan” method, leading to a significant reduction of the shear stresses.
For an initial design or assessment of a reinforced concrete solid slab bridge, spreadsheet-based... more For an initial design or assessment of a reinforced concrete solid slab bridge, spreadsheet-based or hand calculations are typically used. The shear stress is compared to the shear capacity as prescribed by the code. The distributed loads result in a uniform shear stress at the support. Concentrated loads are less straightforward to take into account. It is known that transverse load redistribution occurs in slabs. To explore the topic of transverse load redistribution, experiments on elements subjected to a concentrated load close to the support were carried out. These elements had an increasing width, starting at 0.5 m and increasing with steps of 0.5 m up to 2.5 m, so that the effect of transverse load redistribution could be studied. The threshold effective width resulting from the experiments was then compared to load spreading methods, in order to give recommendations for the practical use with concentrated loads. It was found that the load spreading method as used in French practice is to be preferred. As compared to load spreading methods that were used previously, the French load spreading method results in smaller shear stresses at the support. This result allows for more economic designs and provides a better assessment tool.
International IABSE Conference, Assessment, Upgrading and Refurbishment of Structures, May 2013
The capacity of reinforced concrete solid slab bridges in shear is assessed by comparing the desi... more The capacity of reinforced concrete solid slab bridges in shear is assessed by comparing the design beam shear resistance to the design value of the applied shear force due to the permanent actions and live loads. Results from experiments on half-scale continuous slab bridges are used to develop a set of recommendations for the assessment of slab bridges in shear. A method is proposed allowing to take the transverse force redistribution in slabs under concentrated loads into account, as well as a horizontal load spreading method for the concentrated loads. For selected cases of existing straight solid slab bridges, a comparison is made between the results based on the shear capacity according to the Dutch Code NEN 6720 and from the combination of the Eurocode (EN 1992-1-1:2005) with the recommendations, showing an improved agreement.
In reinforced concrete one-way slabs, two limit states related to shear need to be checked: beam... more In reinforced concrete one-way slabs, two limit states related to shear need to be checked: beam shear over an effective width at the support and punching shear on a perimeter around the load. Current code provisions are based on shear tests on heavily reinforced slender beams under point loads. The question remains if these procedures are valid for wide beams and slabs under point loads close to the support. To evaluate the shear capacity of reinforced concrete slabs and the associated effective width, a series of experiments is carried out on eight continuous one-way slabs and twelve continuous slab strips loaded close to the simple and continuous supports. Test results are compared to current code provisions and methods to calculate the shear capacity from the literature. The influence of the shear span to depth ratio, the size of the loading plate and the overall width of the specimen are discussed. From these results follows that the behavior in shear of slabs and beams is not identical. The effective slab width, used for calculating the beam shear capacity, is recommended to be based on load spreading under 45° from the far side of the loading plate towards the support.
The combination of increased live loads and a more conservative shear capacity in the recently im... more The combination of increased live loads and a more conservative shear capacity in the recently implemented Eurocodes, resulted in a large number of existing solid slab bridges in the Netherlands being shear-critical upon assessment. However, an enhancement of the shear capacity can occur in slabs under concentrated wheel loads due to transverse load redistribution. To quantify this effect, a comprehensive series of experiments on slabs and slabs strips under a concentrated load near to the support and under a combination of a concentrated and a line load was carried out. The experiments show the difference in behaviour for slabs, carrying the load in a two-dimensional way, as compared to beams in shear. The results from the laboratory research are used to develop recommendations, that are easily used in combination with the codes. These recommendations are implemented in a spreadsheet-based first-level assessment tool, the Quick Scan method. The assessment with this tool of selected cases of existing solid slab bridges shows that applying the experimental results into the assessment practice leads to an improved selection ability of the Quick Scan method.
International IABSE Conference, Assessment, Upgrading and Refurbishment of Structures, May 2013
Previous experimental research at Delft University of Technology indicated an increased shear cap... more Previous experimental research at Delft University of Technology indicated an increased shear capacity of slabs under concentrated loads as a function of decreasing distance to the adjacent line support. Expressions have been derived for this increase, including the definition of an appropriate effective width. However, it is unknown if the uniformly distributed loads on solid slab bridges, e.g. due to dead loads, that act over the full width can be combined with the effects of concentrated loads acting only over the associated effective width at the support. To study this problem, additional experiments have been carried out at Delft University of Technology, in which a combination of loads consisting of a concentrated load close to the support and a line load over the full slab width are applied. The experimental results prove that the superposition principle applies to combinations of concentrated loads and distributed loads.
Code provisions for one-way shear assume a linear relation between
the shear capacity of a reinfo... more Code provisions for one-way shear assume a linear relation between the shear capacity of a reinforced concrete member and its width. For wide members subjected to a concentrated load, an effective width in shear should be introduced. To study the effective width and the influence of the member width on shear capacity, a series of experiments was carried out on continuous one-way elements of different widths. The size of the loading plate, the moment distribution at the support, and the shear span-depth ratio were varied and studied as a function of the member width. The effective width can be determined by using a 45-degree load-spreading method from the far side of the loading plate to the face of the support. This proposed effective width is easy to implement, yet gives good results in combination with code provisions.
Upon assessment of existing reinforced concrete short-span solid slab bridges according to the re... more Upon assessment of existing reinforced concrete short-span solid slab bridges according to the recently implemented Eurocodes that include more conservative shear capacity provisions and heavier axle loads, a number of these structures
were found to be shear-critical. The results from recent experimental research on the shear capacity of slabs indicate that slabs benefit from transverse load distribution.
Recommendations for the assessment of solid slab bridges in shear are developed on the basis of these experiments. A load spreading method for the concentrated loads is proposed and the applicability of superposition of loading is studied. The resulting most unfavourable position for the design trucks is provided and implemented in the so-called Dutch “Quick Scan” method (QSEC2). Cases of existing bridges are studied with the previously used QS-VBC as well as with the QS-EC2 that includes the recommendations. As a result of the assumed transverse load distribution, the shear stress to be considered at the
support based on the recommendations becomes smaller.
A 55-year-old bridge showed large cracking in the approach bridge caused by restraint of deformat... more A 55-year-old bridge showed large cracking in the approach bridge caused by restraint of deformation and support settlement. After repair, it was uncertain at which crack width the traffic loads on the bridge should be further restricted. The shear capacity was calculated by counting on the aggregate interlock capacity of a supposedly fully cracked cross section. An aggregate interlock relationship between shear capacity and crack width based on an unreinforced section was used to find the maximum allowable crack width. Limits for crack widths at which load restrictions should be imposed were found. The large structural capacity of the cracked concrete section shows that the residual bearing resistance based on the aggregate interlock capacity of reinforced concrete slab bridges with existing cracks is higher than expected. This expected capacity could be calculated with the inclined cracking load from the code provisions. The procedure outlined in this paper can thus be used for the shear assessment of fully cracked cross sections of reinforced concrete bridges.
The Dutch National Annex to Eurocode 2 deviates from Eurocode 2 for the Wöhler curve for concrete... more The Dutch National Annex to Eurocode 2 deviates from Eurocode 2 for the Wöhler curve for concrete in compression, but has a discontinuity in the S–N curve for 1 million load cycles. Therefore, a new expression for concrete subjected to repeated loading is sought, which should be valid, yet not overly conservative, for high strength concrete. A database of experiments on high strength concrete tested in compressive fatigue is developed, and used to derive new expressions. Two new formulas are proposed: (1) for the assessment of the fatigue strength of existing structures, and (2) a simplified method for design.
Understanding the behavior of concrete in fatigue is essential for understanding the behavior of ... more Understanding the behavior of concrete in fatigue is essential for understanding the behavior of concrete bridges subjected to repeated loads. The Dutch National Annex to the Eurocode prescribes a different expression for the Wöhler curve for compression fatigue than the Eurocode itself, and does not have a smooth transition for 106 load cycles. A new expression for concrete in compression fatigue is thus necessary. This new expression should be valid, yet not overly conservative, for high strength concrete. Therefore, a database of experiments on (ultra) high strength concrete tested in compressive fatigue is used to validate the new proposal. A proposal for the assessment of the fatigue strength of existing structures is prepared. For design, a simplified method is proposed. An expression for the fatigue strength of concrete under compression, suitable for high strength concrete, is now available, which can replace the previous fatigue expressions used in The Netherlands.
One-way slabs supported by line supports and reinforced with deformed bars were shown previously ... more One-way slabs supported by line supports and reinforced with deformed bars were shown previously to behave differently in (one-way) shear than beams. For the application to existing slab bridges, the influence on the shear capacity of using plain reinforcement bars and of supporting the slab by discrete bearings is investigated. To study these parameters and their influence on the shear capacity, a series of experiments was carried out on continuous one-way slabs (5 m x 2.5 m x 0.3 m), subjected to concentrated loads close to the support line. The results from these experiments are compared to code provisions and a method developed by Regan. These experiments confirm the findings that slabs subjected to concentrated loads close to supports have larger shear capacities than beams.
When the shear resistance of prestressed beams with stirrups is determined with the current Euroc... more When the shear resistance of prestressed beams with stirrups is determined with the current Eurocode, no distinction is made between regions with and without flexural cracks. This while it may be expected that a region without flexural cracks will have a higher shear resistance. This is due to the lower longitudinal strains and the narrow crack widths, resulting in a higher contribution of aggregate interlock. Also, the Eurocode does not take into account that in regions without flexural cracks, a significant part of the shear force is transferred through the uncracked flanges. This article proposes therefore a shear resistance model, based on Modified Compression Field Theory (MCFT), that does consider the low longitudinal strains and shear transfer through the uncracked flanges. From a comparison it was found that the proposed model can determine shear resistance as accurately as the most comprehensive level III approach of the Model Code 2010. However, the proposed model was foun...
The capacity of solid slab bridges in shear is assessed by comparing the design beam shear resist... more The capacity of solid slab bridges in shear is assessed by comparing the design beam shear resistance to the design value of the applied shear force due to the permanent actions and traffic loads. The transverse distribution of loads which occurs in slabs is thus not taken into account. Experiments on slabs under concentrated loads are carried out at Delft University of Technology. The results of these experiments are the basis for recommendations for the assessment of solid slab bridges. A slab factor and a horizontal load spreading method to determine the effective width are proposed. Preliminary results from an additional series of experiments confirm the hypothesis of superposition.
In de afgelopen decennia zijn verkeerslasten en de verkeersintensiteit op de Nederlandse wegen e... more In de afgelopen decennia zijn verkeerslasten en de verkeersintensiteit op de Nederlandse wegen en kunstwerken drastisch toegenomen. Veel van die kunstwerken zijn uitgevoerd als plaatviaducten zonder schuifwapening. De vraag bestaat of het afschuifdraagvermogen van deze viaducten nog steeds voldoende is. Op basis van experimenteel en literatuuronderzoek is een nieuw lastspreidingsmodel ontwikkeld aan de TU Delft voor toepassing in de quick-scanmethode van Rijkswaterstaat.
As a result of the heavier live load models and more conservative shear approaches prescribed by ... more As a result of the heavier live load models and more conservative shear approaches prescribed by the recently implemented Eurocodes, a large number of existing reinforced concrete solid slab bridges in the Netherlands were found to be shear-critical. The beneficial effect of the transverse load redistribution in slabs under concentrated loads is not taken into account. To quantify this effect, a comprehensive number of experiments was carried out. These results are used to formulate recommendations for the assessment practice for the case of solid slab bridges. The recommendations focus on the effective width over which the axle load can be distributed and its lower bound, the beneficial effect of transverse load redistribution and the influence of the yield strength of the reinforcement on the lower bound of the shear capacity. These recommendations are implemented in the “Quick Scan” method, leading to a significant reduction of the shear stresses.
For an initial design or assessment of a reinforced concrete solid slab bridge, spreadsheet-based... more For an initial design or assessment of a reinforced concrete solid slab bridge, spreadsheet-based or hand calculations are typically used. The shear stress is compared to the shear capacity as prescribed by the code. The distributed loads result in a uniform shear stress at the support. Concentrated loads are less straightforward to take into account. It is known that transverse load redistribution occurs in slabs. To explore the topic of transverse load redistribution, experiments on elements subjected to a concentrated load close to the support were carried out. These elements had an increasing width, starting at 0.5 m and increasing with steps of 0.5 m up to 2.5 m, so that the effect of transverse load redistribution could be studied. The threshold effective width resulting from the experiments was then compared to load spreading methods, in order to give recommendations for the practical use with concentrated loads. It was found that the load spreading method as used in French practice is to be preferred. As compared to load spreading methods that were used previously, the French load spreading method results in smaller shear stresses at the support. This result allows for more economic designs and provides a better assessment tool.
International IABSE Conference, Assessment, Upgrading and Refurbishment of Structures, May 2013
The capacity of reinforced concrete solid slab bridges in shear is assessed by comparing the desi... more The capacity of reinforced concrete solid slab bridges in shear is assessed by comparing the design beam shear resistance to the design value of the applied shear force due to the permanent actions and live loads. Results from experiments on half-scale continuous slab bridges are used to develop a set of recommendations for the assessment of slab bridges in shear. A method is proposed allowing to take the transverse force redistribution in slabs under concentrated loads into account, as well as a horizontal load spreading method for the concentrated loads. For selected cases of existing straight solid slab bridges, a comparison is made between the results based on the shear capacity according to the Dutch Code NEN 6720 and from the combination of the Eurocode (EN 1992-1-1:2005) with the recommendations, showing an improved agreement.
In reinforced concrete one-way slabs, two limit states related to shear need to be checked: beam... more In reinforced concrete one-way slabs, two limit states related to shear need to be checked: beam shear over an effective width at the support and punching shear on a perimeter around the load. Current code provisions are based on shear tests on heavily reinforced slender beams under point loads. The question remains if these procedures are valid for wide beams and slabs under point loads close to the support. To evaluate the shear capacity of reinforced concrete slabs and the associated effective width, a series of experiments is carried out on eight continuous one-way slabs and twelve continuous slab strips loaded close to the simple and continuous supports. Test results are compared to current code provisions and methods to calculate the shear capacity from the literature. The influence of the shear span to depth ratio, the size of the loading plate and the overall width of the specimen are discussed. From these results follows that the behavior in shear of slabs and beams is not identical. The effective slab width, used for calculating the beam shear capacity, is recommended to be based on load spreading under 45° from the far side of the loading plate towards the support.
The combination of increased live loads and a more conservative shear capacity in the recently im... more The combination of increased live loads and a more conservative shear capacity in the recently implemented Eurocodes, resulted in a large number of existing solid slab bridges in the Netherlands being shear-critical upon assessment. However, an enhancement of the shear capacity can occur in slabs under concentrated wheel loads due to transverse load redistribution. To quantify this effect, a comprehensive series of experiments on slabs and slabs strips under a concentrated load near to the support and under a combination of a concentrated and a line load was carried out. The experiments show the difference in behaviour for slabs, carrying the load in a two-dimensional way, as compared to beams in shear. The results from the laboratory research are used to develop recommendations, that are easily used in combination with the codes. These recommendations are implemented in a spreadsheet-based first-level assessment tool, the Quick Scan method. The assessment with this tool of selected cases of existing solid slab bridges shows that applying the experimental results into the assessment practice leads to an improved selection ability of the Quick Scan method.
International IABSE Conference, Assessment, Upgrading and Refurbishment of Structures, May 2013
Previous experimental research at Delft University of Technology indicated an increased shear cap... more Previous experimental research at Delft University of Technology indicated an increased shear capacity of slabs under concentrated loads as a function of decreasing distance to the adjacent line support. Expressions have been derived for this increase, including the definition of an appropriate effective width. However, it is unknown if the uniformly distributed loads on solid slab bridges, e.g. due to dead loads, that act over the full width can be combined with the effects of concentrated loads acting only over the associated effective width at the support. To study this problem, additional experiments have been carried out at Delft University of Technology, in which a combination of loads consisting of a concentrated load close to the support and a line load over the full slab width are applied. The experimental results prove that the superposition principle applies to combinations of concentrated loads and distributed loads.
Code provisions for one-way shear assume a linear relation between
the shear capacity of a reinfo... more Code provisions for one-way shear assume a linear relation between the shear capacity of a reinforced concrete member and its width. For wide members subjected to a concentrated load, an effective width in shear should be introduced. To study the effective width and the influence of the member width on shear capacity, a series of experiments was carried out on continuous one-way elements of different widths. The size of the loading plate, the moment distribution at the support, and the shear span-depth ratio were varied and studied as a function of the member width. The effective width can be determined by using a 45-degree load-spreading method from the far side of the loading plate to the face of the support. This proposed effective width is easy to implement, yet gives good results in combination with code provisions.
Upon assessment of existing reinforced concrete short-span solid slab bridges according to the re... more Upon assessment of existing reinforced concrete short-span solid slab bridges according to the recently implemented Eurocodes that include more conservative shear capacity provisions and heavier axle loads, a number of these structures
were found to be shear-critical. The results from recent experimental research on the shear capacity of slabs indicate that slabs benefit from transverse load distribution.
Recommendations for the assessment of solid slab bridges in shear are developed on the basis of these experiments. A load spreading method for the concentrated loads is proposed and the applicability of superposition of loading is studied. The resulting most unfavourable position for the design trucks is provided and implemented in the so-called Dutch “Quick Scan” method (QSEC2). Cases of existing bridges are studied with the previously used QS-VBC as well as with the QS-EC2 that includes the recommendations. As a result of the assumed transverse load distribution, the shear stress to be considered at the
support based on the recommendations becomes smaller.
A 55-year-old bridge showed large cracking in the approach bridge caused by restraint of deformat... more A 55-year-old bridge showed large cracking in the approach bridge caused by restraint of deformation and support settlement. After repair, it was uncertain at which crack width the traffic loads on the bridge should be further restricted. The shear capacity was calculated by counting on the aggregate interlock capacity of a supposedly fully cracked cross section. An aggregate interlock relationship between shear capacity and crack width based on an unreinforced section was used to find the maximum allowable crack width. Limits for crack widths at which load restrictions should be imposed were found. The large structural capacity of the cracked concrete section shows that the residual bearing resistance based on the aggregate interlock capacity of reinforced concrete slab bridges with existing cracks is higher than expected. This expected capacity could be calculated with the inclined cracking load from the code provisions. The procedure outlined in this paper can thus be used for the shear assessment of fully cracked cross sections of reinforced concrete bridges.
The Dutch National Annex to Eurocode 2 deviates from Eurocode 2 for the Wöhler curve for concrete... more The Dutch National Annex to Eurocode 2 deviates from Eurocode 2 for the Wöhler curve for concrete in compression, but has a discontinuity in the S–N curve for 1 million load cycles. Therefore, a new expression for concrete subjected to repeated loading is sought, which should be valid, yet not overly conservative, for high strength concrete. A database of experiments on high strength concrete tested in compressive fatigue is developed, and used to derive new expressions. Two new formulas are proposed: (1) for the assessment of the fatigue strength of existing structures, and (2) a simplified method for design.
Understanding the behavior of concrete in fatigue is essential for understanding the behavior of ... more Understanding the behavior of concrete in fatigue is essential for understanding the behavior of concrete bridges subjected to repeated loads. The Dutch National Annex to the Eurocode prescribes a different expression for the Wöhler curve for compression fatigue than the Eurocode itself, and does not have a smooth transition for 106 load cycles. A new expression for concrete in compression fatigue is thus necessary. This new expression should be valid, yet not overly conservative, for high strength concrete. Therefore, a database of experiments on (ultra) high strength concrete tested in compressive fatigue is used to validate the new proposal. A proposal for the assessment of the fatigue strength of existing structures is prepared. For design, a simplified method is proposed. An expression for the fatigue strength of concrete under compression, suitable for high strength concrete, is now available, which can replace the previous fatigue expressions used in The Netherlands.
One-way slabs supported by line supports and reinforced with deformed bars were shown previously ... more One-way slabs supported by line supports and reinforced with deformed bars were shown previously to behave differently in (one-way) shear than beams. For the application to existing slab bridges, the influence on the shear capacity of using plain reinforcement bars and of supporting the slab by discrete bearings is investigated. To study these parameters and their influence on the shear capacity, a series of experiments was carried out on continuous one-way slabs (5 m x 2.5 m x 0.3 m), subjected to concentrated loads close to the support line. The results from these experiments are compared to code provisions and a method developed by Regan. These experiments confirm the findings that slabs subjected to concentrated loads close to supports have larger shear capacities than beams.
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Papers by Cor van der Veen - CITG
the shear capacity of a reinforced concrete member and its width.
For wide members subjected to a concentrated load, an effective
width in shear should be introduced. To study the effective width
and the influence of the member width on shear capacity, a series
of experiments was carried out on continuous one-way elements of
different widths. The size of the loading plate, the moment distribution
at the support, and the shear span-depth ratio were varied
and studied as a function of the member width. The effective width
can be determined by using a 45-degree load-spreading method
from the far side of the loading plate to the face of the support.
This proposed effective width is easy to implement, yet gives good
results in combination with code provisions.
were found to be shear-critical. The results from recent experimental research on the shear capacity of slabs indicate that slabs benefit from transverse load distribution.
Recommendations for the assessment of solid slab bridges in shear are developed on the basis of these experiments. A load spreading method for the concentrated loads is proposed and the applicability of superposition of loading is studied. The resulting most unfavourable position for the design trucks is provided and implemented in the so-called Dutch “Quick Scan” method (QSEC2). Cases of existing bridges are studied with the previously used QS-VBC as well as with the QS-EC2 that includes the recommendations. As a result of the assumed transverse load distribution, the shear stress to be considered at the
support based on the recommendations becomes smaller.
This expected capacity could be calculated with the inclined cracking load from the code provisions. The procedure outlined in this paper can thus be used for the shear assessment of fully cracked cross sections of reinforced concrete bridges.
bearings is investigated. To study these parameters and their influence on the shear capacity, a series of experiments was carried out on continuous one-way slabs (5 m x 2.5 m x 0.3 m), subjected to concentrated loads close to the support line. The results from these experiments are compared to code
provisions and a method developed by Regan. These experiments confirm the findings that slabs subjected to concentrated loads close to supports have larger shear capacities than beams.
the shear capacity of a reinforced concrete member and its width.
For wide members subjected to a concentrated load, an effective
width in shear should be introduced. To study the effective width
and the influence of the member width on shear capacity, a series
of experiments was carried out on continuous one-way elements of
different widths. The size of the loading plate, the moment distribution
at the support, and the shear span-depth ratio were varied
and studied as a function of the member width. The effective width
can be determined by using a 45-degree load-spreading method
from the far side of the loading plate to the face of the support.
This proposed effective width is easy to implement, yet gives good
results in combination with code provisions.
were found to be shear-critical. The results from recent experimental research on the shear capacity of slabs indicate that slabs benefit from transverse load distribution.
Recommendations for the assessment of solid slab bridges in shear are developed on the basis of these experiments. A load spreading method for the concentrated loads is proposed and the applicability of superposition of loading is studied. The resulting most unfavourable position for the design trucks is provided and implemented in the so-called Dutch “Quick Scan” method (QSEC2). Cases of existing bridges are studied with the previously used QS-VBC as well as with the QS-EC2 that includes the recommendations. As a result of the assumed transverse load distribution, the shear stress to be considered at the
support based on the recommendations becomes smaller.
This expected capacity could be calculated with the inclined cracking load from the code provisions. The procedure outlined in this paper can thus be used for the shear assessment of fully cracked cross sections of reinforced concrete bridges.
bearings is investigated. To study these parameters and their influence on the shear capacity, a series of experiments was carried out on continuous one-way slabs (5 m x 2.5 m x 0.3 m), subjected to concentrated loads close to the support line. The results from these experiments are compared to code
provisions and a method developed by Regan. These experiments confirm the findings that slabs subjected to concentrated loads close to supports have larger shear capacities than beams.