When it comes to wind loads on building type structures as per ASCE 7, numerous resources can be found to supplement design standards and aid engineers with this lateral load application. However, engineers may find it more difficult to find similar resources for wind loading on non-building type structures. This article will examine the steps to calculate and apply wind loads as per ASCE 7-22 on a circular reinforced concrete tank with a dome roof.
In the case of using slow‑curing concrete (usually for thick components), you can reduce the calculated minimum reinforcement by a factor of 0.85 to apply the load due to restraint, according to EN 1992‑1‑1, Section 7.3.2. However, a precondition for reduction is that the characteristic value of the strength development r = fcm2 / fcm28 does not exceed 0.3. Other key requirements for the application of this reinforcement reduction are specified explicitly in the final planning documents.
You can use the "Free Circular Load" option in RFEM to apply a partial uplift force to a cone‑shaped floor slab. It can be defined as linearly variable. The definition of center C and the outer boundary R can be specified easily, using the select function.
In the "Material Model - Isotropic Nonlinear Elastic" window, you can select the yield laws according to the von Mises, Tresca, Drucker-Prager, and Mohr-Coulomb yield rules. This makes it possible to describe the elasto-plastic material behavior. The yield function depends on the principal stresses or the invariants of a stress tensor. The criteria apply to 2D and 3D material models.
RFEM and RSTAB offer different options to model bored piles. One option is to display bored piles as single-valued supports or hinged columns. Another option is realistic modeling while taking the soil into account by means of applying a member elastic foundation. The two following examples will describe it in detail. However, pile base resistance, skin friction, and soil layers are not considered in this technical article.
When it comes to wind loads on building type structures as per ASCE 7, numerous resources can be found to supplement design standards and aid engineers with this lateral load application. However, engineers may find it more difficult to find similar resources for wind loading on non-building type structures. This article will examine the steps to calculate and apply wind loads as per ASCE 7-16 on a circular reinforced concrete tank with a dome roof.
You can apply nominal temperature‑time curves in RFEM or RSTAB using RF‑/STEEL EC3. For this, the standard time-temperature curve (ETK), the external fire curve and the hydrocarbon fire curve are implemented in the program. Based on these temperature curves, the add‑on module can calculate the temperature in the steel cross‑section and thus perform the fire design using the determined temperatures. This article explains the thermal behavior of structural steel, as this has a direct impact on the calculation of component temperatures in RF‑/STEEL EC3.
Using RF-/STEEL EC3, you can apply nominal temperature-time curves in RFEM or RSTAB. For this, the standard time-temperature curve (ETK), the external fire curve and the hydrocarbon fire curve are implemented in the program. Based on these diagrams, the add-on module can calculate the temperature in the steel cross-section and thus perform the fire design. This article explains the behavior of protected and unprotected steel cross‑sections.
In the case of a parallel offset of the structural plane of members and surfaces and also applying an axial offset to members, for example, the function of eccentricities may be useful.
Using RF-/STEEL EC3, you can apply nominal temperature-time curves in RFEM or RSTAB. The standard time-temperature curve (ETK), the external fire curve and the hydrocarbon fire curve are implemented. Moreover, the program provides the option to directly specify the final temperature of steel. This steel temperature can be calculated using the parametric temperature-time curve, as described in the Annex to DIN EN 1992-1-2. The different fire exposures are explained in this article.
In order to use internal forces from average regions also for the design of concrete surfaces, you have to activate them in the module. For this, click the [Details] button in the "Tools" tab and select the option "Apply the averaged internal forces in the defined average region for the ULS calculation and for the analytic method of SLS calculation."
According to DIN EN 1990/NA:2010‑12 – NDP to A.1.2.1(1) Comment 2, it is necessary to apply only one of the two climatic actions in the combination expressions for actions according to 6.4.3 and 6.5.3 in the case of places located up to +1,000 m above mean sea level if snow and wind are available as collateral actions, in addition to non‑climatic leading action.
The network licenses of Dlubal Software provide a very convenient solution for engineering offices as well as for users who are often on the move. This can be helpful if you are in a consulting meeting with a building owner and want to directly apply the current changes and show the solution immediately. You only need an Internet and a VPN connection in your office to access all your purchased licenses.
For structural components consisting of slabs, it is necessary to perform shear design on the locations with concentrated load introduction, applying the punching shear design rules according to Sect. 6.4 of EN 1992‑1‑1 [1]. The concentrated load introduction is present on the individual locations, for example by columns, concentrated load, or nodal supports. In addition, the end of linear load introduction on slabs is also regarded as concentrated load introduction. For example, this includes wall ends, wall corners, and ends or corners of line loads and line supports. You can perform the punching shear design for floor slabs or foundations, considering the existing available plate topology about the designed node of punching shear. The punching shear design according to EN 1992‑1‑1 checks that the acting shear force vEd does not exceed the resistance vRd.
In addition to the stability designs according to EN 1993‑1‑1, Sections 6.3.1 through 6.3.3, you can apply the General Method according to EN 1993‑1‑1, 6.3.4 in RF‑/STEEL EC3.
In addition to manually entering values, you can enter line loads in the "Member Load" dialog box using the "Multi-Layer Composition" function. This is a library that contains the compositions of several layers for applying loads. You can freely specify the layer structure using the parameters of description, thickness, density, or surface load, and comment for each layer.
When using the wind load generator for vertical walls with a roof, it may be necessary to load the edge members on eaves or on a gable only with the wind loads of the roof. For structural reasons, the horizontal wind loads should apply to the vertical walls by the facade. In previous versions, it was necessary to apply the wind loads separately to the walls and the roof with the corresponding generators and exclude the unwanted members.
A new direction for temperature load is available in RFEM. Now, it is also possible to apply temperature loads with radial load distribution on a structure. The load is defined using an outer and an inner node, and an axis around which the radial load is applied.
In RFEM and RSTAB, you can now rotate nodal loads or apply them on member axes. Thus, inclined members can also be loaded with nodal loads perpendicularly or along the member axis.