Experimental and Theoretical Study of Internal Pressure Loads on Boundary Walls under Gusty Wind Conditions

In general, the internal pressure of fully closed envelops or

buildings depends on the position and size of accurate vent

holes, the envelop adequate volume, and the external surface

pressure due to the passing wind characteristics. The magnitude of internal pressure loads acting on a closed envelop or

building walls is very small compared to the magnitude of

external pressure loads. But a failure of walls with fully

closed envelop can create a dominant opening and a vast

increment in the magnitude of internal pressures. The combination of internal and large external pressure loads in the

same direction causes failures in the walls of any closed

envelops. Due to the obtained small magnitude of the values,

the case studies of internal pressure loads have received less

interest by the researchers. One of the external pressure

load studies, under gusty wind conditions, has been presented by Chevula et al. The first study of internal pressure loads under steady flow conditions had been introduced

by Euteneuer. He proposed an expression to predict the

change in the internal pressure loads due to a sudden change

in external pressure by neglecting the effects on the flow

through the failure of envelop openings. He also found that

a transient response of internal pressure may present (which

causes damped oscillations too) in case of creation of a sudden opening in the closed building. Therefore, the failure of closed envelops or overloaded envelop components

can be obtained by the vast wind flows (tropical cyclones)

and huge variations in the internal and external pressure

loads. The estimation of the pressure load fluctuations

obtained in both steady and unsteady flow conditions on a

closed building envelop is more complicated due to the complexity involved in the measurements of flow analysis

parameters. To overcome the complications raised, Liu

and Rhee presented the formulations for the internal

pressure loads under steady and unsteady flow conditions.

A full-scale study on internal pressure loads was conducted

by Ginger et al and reported that the mean magnitude

of internal pressure loads of a nominally sealed bundling

or envelop is smaller than the magnitude of the external

pressure loads. The internal pressure variations were measured by a model of a typical two-storey house in an open country exposure on various combinations of openings by

Kopp et al. The internal and external pressure measurements have been obtained in the case of compartmentalizing

into the connecting attic and living volumes, and the Helmholtz resonance effects have been concluded. Holmes and

Chaplin  proposed some classical methods which are relevant to calculating the influences of the internal pressures in

various closed building models. In the field of space vehicle

design, payload assembly, and launch, we can find some studies relevant to the internal pressure loads under gusty flow

conditions, namely, space vehicle compartment vent (NASA

SP-8060) . Sanz-Andres et al.analyzed the variation

of the internal pressure loads during the climb of a spacecraft

through the atmosphere. In the applications of payloads

placed in fairing depressurization of spacecraft, Sanz-Andres

and Navarro-Medina proposed an analytical expression

that can estimate the depressurization vent size.